CN1720218A - Process for producing alpha-hydroxycarboxylic ester - Google Patents

Abstract

The present invention provides a more efficient process for alpha-hydroxycarboxylic ester production in which the alpha-hydroxycarboxylic ester is more effectively inhibited or prevented from undergoing side reactions than in conventional techniques. The process for producing an alpha-hydroxycarboxylic ester comprises the following steps (1) to (3): a step (1) in which either (i) a 1,2-diol and the same or another 1,2-diol or (ii) a 1,2-diol and an alcohol are reacted in the presence of oxygen to obtain a reaction product containing an alpha-hydroxycarboxylic ester; a step (2) in which the reaction product obtained in the step (1) is distilled under vacuum to separate out the alpha-hydroxycarboxylic ester; and a step (3) in which part or all of the water is removed from the reaction product obtained in the step (1) and a mixture comprising the 1,2-diol and/or alcohol remaining unreacted is supplied to the step (1).

Description

The manufacture method of alpha-hydroxycarboxylic ester

Technical field

The present invention relates to the manufacture method of alpha-hydroxycarboxylic ester.

Background technology

The manufacture method of alpha-hydroxycarboxylic ester such as ethyl glycolate, lactate is as the raw material (polycondensation monomer) of various synthetic resins such as polyoxyethylene glycol acid.And,, be the compound that can effectively be used as washing composition, etchant industrial.

All the time, known, as the manufacture method of the ethyl glycolate of one of alpha-hydroxycarboxylic ester the method shown in for example following (1)～(4) is arranged:

(1) in the presence of heteropolyacid, after the synthetic poly-glycollide of formaldehyde and carbon monoxide, adds the method that alcohol the decomposes claim of Japanese kokai publication hei 6-228045 communique (for example, with reference to);

(2) after by formaldehyde and carbon monoxide synthesizing of glycolate, then carry out esterification method (for example, announcing No. 9511114) with reference to Korean Patent with alcohol;

(3) in the presence of catalyzer, carry out the method claim of Japanese kokai publication hei 8-104665 communique (for example, with reference to) of the oxidisability esterification of oxalic dialdehyde and alcohol;

(4) with oxalate diester hydrogenant method the claim of Japanese kokai publication hei 6-135895 communique (for example, with reference to).

With respect to these manufacture method, the application's applicant has developed the manufacture method (for example, the specification sheets (claim) of the Japanese application for a patent for invention 2002-204748 of reference) of oxidisability esterification reaction.This manufacture method is to make 1 in the presence of oxygen, and the 2-glycol is made the method for alpha-hydroxycarboxylic ester with the alcohol reaction.According to this manufacture method, can make alpha-hydroxycarboxylic ester more efficiently.

But the poor heat resistance of alpha-hydroxycarboxylic ester, particularly ethyl glycolate more easily induces reaction.Therefore, manufacture method also might be in reaction described in the above-mentioned Japanese application for a patent for invention 2002-204748 (claim), in processes such as distillation, alpha-hydroxycarboxylic ester is heated and causes side reaction (for example oligomeric materialization, hydrolysis, transesterification reaction etc.), so that reduce the yield of purpose product.And will also low low boiling component distill except that going to system than the boiling point of alpha-hydroxycarboxylic ester by distillation, the result just might make the reaction overbalance, so that promotes side reaction.And in the prior art, the reason alpha-hydroxycarboxylic ester is synthesized to always to be changed till refining, so that manufacturing purpose product fully efficiently, so need make more efficiently the method for alpha-hydroxycarboxylic ester now.

Alpha-hydroxycarboxylic ester class condenses (2-hydroxycarboxylic acid condenses) can be enumerated for example poly(lactic acid), polyglycolic acid etc.They can obtain by alpha-hydroxy carboxylic acid compounds such as lactic acid, oxyacetic acid (2-hydroxycarboxylic acid) dehydrating condensation usually the claim of Japanese kokai publication hei 7-102044 communique (for example, with reference to).And in this case, the end in the condenses end is a hydroxyl, and the other end is a carboxyl.

When making alpha-hydroxy carboxylic acid compounds class condenses, have to be difficult to reach the high-molecular weight problem by the dehydrating condensation of above-mentioned alpha-hydroxy carboxylic acid compounds.Therefore, in fact, making molecular weight behind thousands of～tens thousand of condenses, make cyclic esters such as rac-Lactide or glycollide by a thermo-cracking, this cyclic ester is made high molecular alpha-hydroxycarboxylic ester class condenses through ring-opening polymerization.

In addition, known is raw material with hydroxycarboxylic acid esters such as methyl lactate, n-Butyl lactates in addition, through dealcoholization condensation reaction, makes the method for alpha-hydroxy carboxylic acid compounds class condenses.According to this method, the end in the condenses end is a hydroxyl, and the other end is ester groups such as methyl ester group, the butyl ester group claim of Japanese kokai publication hei 7-173264 communique (for example, with reference to).And this condenses also has to be difficult to reach high molecular and manufacturing process complicated problems with the same by alpha-hydroxy carboxylic acid compounds deutero-condenses.

Therefore, people wish to develop compared with prior art, can reach high-molecular weight alpha-hydroxy carboxylic acid compounds class condenses and easy manufacture method thereof.

Summary of the invention

As mentioned above, people seek to develop with the manufacture method of prior art and compare, and can suppress or prevent the side reaction by the alpha-hydroxycarboxylic ester generation, and can make the method for alpha-hydroxycarboxylic ester more efficiently.

Therefore, the objective of the invention is to, provide with the manufacture method of prior art and compare, can suppress or prevent side reaction, and can make the method for alpha-hydroxycarboxylic ester more efficiently by the alpha-hydroxycarboxylic ester generation.

In addition, people also seek exploitation compared with prior art, can reach high-molecular weight alpha-hydroxy carboxylic acid compounds class condenses and easy manufacture method thereof.

Therefore, another object of the present invention is to, provide to reach alpha-hydroxy carboxylic acid compounds class condenses and the easy manufacture method thereof that high-molecular weight, especially two ends have hydroxyl.

The inventor after furtheing investigate repeatedly, found that in view of prior art problems the alpha-hydroxycarboxylic ester manufacture method and the alpha-hydroxy carboxylic acid compounds class condenses manufacture method that comprise certain working procedure can be reached above-mentioned purpose, thereby finish the present invention.

That is, the present invention relates to following alpha-hydroxycarboxylic ester manufacture method and alpha-hydroxy carboxylic acid compounds condenses.

1. the manufacture method of alpha-hydroxycarboxylic ester is characterized in that, comprises following operation 1～3:

(1) in the presence of oxygen, make (i) 1, between the 2-glycol or (ii) 1,2-glycol and alcohol reaction obtain containing the operation 1 of the resultant of reaction of alpha-hydroxycarboxylic ester;

(2) under reduced pressure, to the distillation of operation 1 gained resultant of reaction, the operation 2 of separating alpha-hydroxycarboxylic ester; With

(3) from operation 1 gained resultant of reaction, remove part or all of water, to operation 1 supply with contain unreacted 1, the operation 3 of the mixture of 2-glycol and/or alcohol.

2. as manufacture method as described in above-mentioned the 1st, it is characterized in that the distillation in the operation 2 is carried out under the condition of 30～250 ℃ of pressure 13～80000Pa and column bottom temperatures.

3. as manufacture method as described in above-mentioned the 1st, it is characterized in that in operation 3, said mixture contains the water of 0～20 quality %.

4. as manufacture method as described in above-mentioned the 1st, it is characterized in that when operation 1～3 was in stable state, the reaction raw materials in the operation 1 contained the water of 0.1～15 quality %.

5. as manufacture method as described in above-mentioned the 1st, it is characterized in that, in operation 3, from resultant of reaction, remove more than the 30 quality % that anhydrate, mixture is supplied to operation 1.

6. as manufacture method as described in above-mentioned the 1st, it is characterized in that, in operation 2, when implementing distillation, operation 1 gained resultant of reaction is made film like, contact, resultant of reaction is heated with hot face.

7. as manufacture method as described in above-mentioned the 1st, it is characterized in that, the reaction in the operation 1, be the particulate that precious metal forms be supported at supported catalyst in the presence of carry out.

8. as manufacture method as described in above-mentioned the 1st, it is characterized in that, in operation 1, add alpha-hydroxy carboxylic acid compounds again and/or the alpha-hydroxy carboxylic acid compounds ester oligomer reacts.

9. as manufacture method as described in above-mentioned the 1st, it is characterized in that liquid is supplied to operation 1 and/or operation 2 at the bottom of the distillation Tata that comprises at least a kind of byproduct of reaction that is selected from alpha-hydroxy carboxylic acid compounds and alpha-hydroxy carboxylic acid compounds ester oligomer that will generate in operation 1 and/or operation 2.

10. as manufacture method as described in above-mentioned the 1st, it is characterized in that, in operation 1, make 1,2-two pure and mild alcohol reactions.

11. as manufacture method as described in above-mentioned the 10th, it is characterized in that, in operation 1, also add at least a kind of being selected from alpha-hydroxy carboxylic acid compounds, alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate, alpha-hydroxy carboxylic acid compounds ester oligomer and react.

12. as manufacture method as described in above-mentioned the 10th, it is characterized in that, the reaction in the operation 1, be the particulate that precious metal forms be supported at supported catalyst in the presence of carry out.

13. as manufacture method as described in above-mentioned the 10th, it is characterized in that, in operation 2, reclaim the cut that contains alpha-hydroxycarboxylic ester in the side stream mode.

14. as manufacture method as described in above-mentioned the 10th, it is characterized in that, with liquid at the bottom of the distillation Tata that contains at least a kind the byproduct of reaction that is selected from alpha-hydroxy carboxylic acid compounds, alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate, alpha-hydroxy carboxylic acid compounds ester oligomer that generates in operation 1 and/or the operation 2, be supplied to operation 1 and/or operation 2.

15. as manufacture method as described in above-mentioned the 10th, it is characterized in that, with liquid at the bottom of the tower that contains the alpha-hydroxy carboxylic acid compounds ester oligomer that generates in operation 1 and/or the operation 2 with corresponding to the ester group-C in the oligopolymer (=after O) the pure R-OH of OR (but R is organic residue) contacts, be supplied to operation 1 and/or operation 2.

16., it is characterized in that above-mentioned 1, the 2-glycol is an ethylene glycol as manufacture method as described in above-mentioned the 10th, above-mentioned alpha-hydroxycarboxylic ester is an ethyl glycolate.

17. as following (I)～(III) alpha-hydroxy carboxylic acid compounds class condenses as described in each, wherein,

(I) for containing the alpha-hydroxy carboxylic acid compounds class condensation part shown in the following general formula (2) with shown in the following general formula (3) 1, the alpha-hydroxy carboxylic acid compounds class condenses of 2-glycol chains, its two ends are the alpha-hydroxy carboxylic acid compounds class condenses shown in following general formula (4) or the following general formula (5),

In general formula (2),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

In general formula (3),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

In general formula (4),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

In general formula (5),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

(II) be the alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (6),

In general formula (6), R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group, and the scope of n is 1～200;

(III) be alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (7),

In general formula (7), R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group, and n1, n2 are all more than 1, and the scope of n1+n2 is 2～200.

18. as following (I)～(III) each described alpha-hydroxy carboxylic acid compounds class condenses, it is by in the presence of catalyzer, utilization makes shown in the following general formula (1) 1, the manufacture method of the alpha-hydroxycarboxylic ester of 2-glycol interreaction obtains the alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate, utilize again and take off 1, the reaction of 2-glycol obtains the ester condensation of alpha-hydroxy carboxylic acid compounds hydroxyalkyl, wherein

In general formula (1),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

(I) for containing alpha-hydroxy carboxylic acid compounds class condensation shown in the following general formula (2) part with shown in the following general formula (3) 1, the alpha-hydroxy carboxylic acid compounds class condenses of 2-glycol chains, its two ends are the alpha-hydroxy carboxylic acid compounds class condenses shown in following general formula (4) or the following general formula (5),

In general formula (2),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

In general formula (3),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

In general formula (4),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

In general formula (5),

R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group;

(II) be alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (6),

In general formula (6), R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group, and the scope of n is 1～200;

(III) be alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (7),

In general formula (7), R represents the alkyl of hydrogen or carbonatoms 1～5, and this alkyl can have substituting group, and n1, n2 are all more than 1, and the scope of n1+n2 is 2～200.

19., it is characterized in that the distillation in the operation 2 adopts the multistage distillation tower to carry out as manufacture method as described in above-mentioned the 1st.

20., it is characterized in that the distillation in the above-mentioned operation 2 is carried out as manufacture method as described in above-mentioned the 19th under the condition of 30～250 ℃ of pressure 13～80000Pa and column bottom temperatures.

21. as manufacture method as described in above-mentioned the 19th or the 20th, it is characterized in that, comprise liquid at the bottom of the distillation Tata that contains at least a kind the byproduct of reaction that is selected from alpha-hydroxy carboxylic acid compounds and alpha-hydroxy carboxylic acid compounds ester oligomer that will be in operation 1 and/or the operation 2 generates, be supplied to operation 1 and/or operation 2.

1. the manufacture method of alpha-hydroxycarboxylic ester

The manufacture method manufacture method of alpha-hydroxycarboxylic ester of the present invention is characterized in that, comprises following operation 1～3:

(1) in the presence of oxygen, make (i) 1, between the 2-glycol or (ii) 1,2-glycol and alcohol reaction obtain containing the operation 1 of the resultant of reaction of alpha-hydroxycarboxylic ester;

(2) under reduced pressure, to the distillation of operation 1 gained resultant of reaction, the operation 2 of separating alpha-hydroxycarboxylic ester; With

(3) from operation 1 gained resultant of reaction, remove part or all of water, to operation 1 supply with contain unreacted 1, the operation 3 of the mixture of 2-glycol and/or alcohol.

Below, describe each operation in detail.

[operation 1]

In the operation 1, in the presence of oxygen, make (i) 1, between the 2-glycol or (ii) 1,2-glycol and alcohol reaction obtain containing the resultant of reaction of alpha-hydroxycarboxylic ester.As mentioned above, for obtaining containing the resultant of reaction of alpha-hydroxycarboxylic ester, both can make 1, the interreaction of 2-glycol also can make 1,2-glycol and 1, other alcohol reaction outside the 2-glycol.

1. starting material

1, the 2-glycol does not refer in particular at 1 and 2 alcohol that hydroxyl is arranged, and for example, can be the above polyvalent alcohol of ternary yet.

Particularly, 1, the 2-glycol can be enumerated for example ethylene glycol, 1,2-propylene glycol, 1,2-butyleneglycol, 1, the aliphatics 1 of carbonatomss 2～10 such as 2-hexylene glycol, 2-glycol; Glycerine, tetrahydroxybutane, Xylitol, Sorbitol Powder etc. are at aliphatic polyol of 1 and 2 carbonatoms 3～10 that hydroxyl arranged etc.In addition, also can use above-mentioned 1, the derivative of 2-glycol.

1, the 2-diol, derivatives can be enumerated, 3-chloro-1 for example, the aliphatics 1 of halogen-containing carbonatomss 2～10 such as 2-propylene glycol, 2-glycol; The aliphatics 1 of the carbonatoms 2～10 of band such as 2-phenyl-1 aromatic nucleus, 2-glycol etc.

Wherein, be preferably the aliphatic diol of carbonatomss 2～6 such as ethylene glycol especially.These 1,2-glycol and derivative thereof can use more than a kind or 2 kinds.

Alcohol also can be 1, other alcohol outside the 2-glycol.Its kind does not have specific limited, as long as intramolecularly has hydroxyl, both can be monohydroxy-alcohol, can be the above polyvalent alcohol of binary yet.

Specifically can enumerate for example Fatty Alcohol(C12-C14 and C12-C18) of carbonatomss 1～10 such as methyl alcohol, ethanol, 1-propyl alcohol, 1-butanols, 1-hexanol, 1-octanol; 1,3 butylene glycol, 1, the aliphatic polyol of carbonatomss 3～10 such as 4-butyleneglycol: the aliphatics unsaturated alcohol of carbonatomss such as vinyl carbinol, methylallyl alcohol 3～10; The alcohol of band such as benzylalcohol aromatic nucleus etc.

Wherein, be preferably primary alconol, particularly the aliphatic primary alcohol of carbonatomss 1～4 such as methyl alcohol, ethanol, 1-propyl alcohol, 1-butanols.And be preferably monohydroxy-alcohols such as methyl alcohol, ethanol, 1-propyl alcohol, 1-butanols especially.These alcohol can use more than a kind or 2 kinds.

2. raw-material usage ratio

With regard to starting material, can suitably select 1, the kind of 2-two pure and mild alcohol according to kind of purpose product alpha-hydroxycarboxylic ester etc.

For example, during the synthesizing alcohol acid esters, 1, the 2-glycol can be selected ethylene glycol, and alcohol can be selected primary alconols such as methyl alcohol, ethanol, 1-propyl alcohol, 1-butanols.When only using 1, during the 2-glycol, 1, the 2-glycol is selected for use under the situation of ethylene glycol, can make oxyacetic acid-2-hydroxyl ethyl ester.

With 1, when 2-two pure and mild alcohol are raw material, both ratios are not had specific limited, but alcohol is with respect to 1, the mol ratio of 2-glycol is generally 1: 2～and 50, be preferably 1: 3～20.When being set in this scope, can effectively synthesize alpha-hydroxycarboxylic ester.

3. catalyzer

In the presence of oxygen, make (i) 1, between the 2-glycol or (ii) 1, the 2-glycol can carry out this reaction during with the alcohol reaction as required in the presence of catalyzer.

(a) catalytic active component

The kind of catalyzer is not particularly limited, and is preferably the metal as activeconstituents is supported at supported catalyst, promptly carries to hold the shaped metal catalyzer.

Metal as activeconstituents does not have special restriction, is preferably precious metal, can enumerate for example gold, palladium, ruthenium, rhodium, iridium, platinum etc.Wherein be preferably gold, palladium, ruthenium, more preferably gold.

Catalyzer preferably contains above-mentioned precious metal, preferably except that precious metal, 2B family, 3B family, 4B family, 5B family and the 6B family of also containing the periodic table of elements (" the chemical analysis brief guide is changed the 5th edition " ball is apt to (calendar year 2001)) the 4th cycle of being selected from～the 6th cycle, and the 4th cycle the 8th family at least a kind of element (hereinafter also these elements being called " second element ").Second element can be enumerated for example 2B families such as Zn, Cd, Hg; 3B families such as Ga, In, Tl; 4B families such as Ge, Sn, Pb; 5B families such as As, Sb, Bi; 6B families such as Se, Te, Po; Fe, Co, Ni grade in an imperial examination 8 families etc.

Particularly, when using catalyzer, for example can suitably use the particulate that Au is made second at least a in particulate and/or periodictable the 4th～the 6th cycle 2B family, 3B family, 4B family, 5B family, 6B family or the 4th cycle the 8th family element and Au formation to be stated from supported catalyst.

As the metal of activeconstituents, when containing above-mentioned precious metal, can contain separately, also can contain more than 2 kinds.When containing more than 2 kinds precious metal,, also can partly or entirely form alloy, intermetallics etc. as long as can reach effect of the present invention.

And, when comprising the precious metal and second element,, also can partly or entirely form alloy, intermetallics etc. as long as can reach effect of the present invention as the metal of activeconstituents.The precious metal and second element are supported at carrier with particulate usually.Used catalyzer in the manufacture method of the present invention in the scope of effect of the present invention, also can contain element or impurity outside the precious metal and second element.

As the particle diameter of the metal particle of activeconstituents,, promptly unrestricted as long as can reach predetermined catalytic activity.Median size be generally 10nm following, be preferably 6nm following, more preferably 5nm following, be preferably 1～5nm especially.When being set within this range, can obtain excellent catalytic activity more reliably.The lower value of median size does not have special restriction, considers physical properties, is preferably about 1nm.

In addition, what the median size of metallic particles of the present invention was represented is, with the metallic particles on transmission electron microscope (TEM) the observation carrier, therefrom optional 120, remove (1) from greatly to preceding 10 of little order, with (2) arithmetical av of preceding 10 100 particle grain size after adding up to 20 of order from small to large.And the size distribution maximum value of metallic particles preferably at 1～6nm, particularly preferably in the scope of 1～5nm.Size distribution heals better narrow.Above-mentioned 120 particle grain size standard deviations (Standard Diviation) are preferably below 2, particularly preferably in below 1.5.

Metal active composition loading amount in the catalyzer can suitably be determined according to kind of carrier etc., with respect to 100 mass parts carriers, is generally 0.01～20 mass parts, is preferably 0.1～10 mass parts especially.

(b) carrier

Carrier can use the carrier that all the time is used as support of the catalyst, and there is no particular restriction.For example can use the commercial goods.Also can use the carrier that gets by known method for making.For example, can enumerate metal oxide (silicon-dioxide, aluminum oxide, titanium dioxide, zirconium white, magnesium oxide etc.), complex metal oxides (silica-alumina, titania-silica, silica-magnesia etc.), zeolite (ZSM-5 etc.), medium (meso) porous silicate inorganic oxides such as (MCM-41 etc.); Natural mineral (clay, diatomite, float stone etc.); Carbon material various carriers such as (gac, graphite etc.).Wherein, be preferably inorganic oxide.

Inorganic oxide carrier is preferably porous carrier, particularly is preferably specific surface area (BET method) at 50m ²/ g is above, 100m more preferably ²/ g is above, be preferably 100～800m especially ²The carrier of/g.Support shapes, the no specific limited of size can suitably be determined according to the purposes of end article.

(c) manufacture method of catalyzer

As long as can obtain aforesaid carrier, there is no particular restriction for the manufacture method of catalyzer.For example, can get by at least a carrier that contains to some extent the metal hoped and compound thereof is heat-treated.Metallic compound can be oxyhydroxide, muriate, carboxylate salt, nitrate, alkoxide, methyl ethyl diketone dentate salt etc. any.

Particularly, for example, carry when holding golden particulate, so long as the method that golden particulate is fixed on the carrier can be got final product.Carrying the method for holding for example can utilize coprecipitation method, separate out known methods such as the precipitator method, pickling process, vapor coating method.Wherein be preferably coprecipitation method and separate out the precipitator method, be preferably especially and separate out the precipitator method.With separating out precipitator method manufacturing when can be used for the catalyzer of the 1st operation, can by for example with the auriferous water-soluble cpds aqueous solution with after inorganic oxide carrier mixes, the solids component of recovery is fired and is obtained catalyzer.

And when on carrier, being carried with metal more than 2 kinds, carry that to hold order also unrestricted, wantonly a kind formerly all can, carry out simultaneously also can.That is, can be after (A) precious metal is supported at carrier, after carrying method, (B) second element of holding second element again and being supported at carrier, carry method, (C) precious metal and second element of holding precious metal and be supported at arbitrary method in the method on the carrier simultaneously.

4. reaction conditions

In the presence of oxygen, make (i) 1, between the 2-glycol or (ii) 1, the reaction of 2-glycol and alcohol can be any in liquid phase reaction, the gas-phase reaction etc.Oxygen preferably uses molecular oxygen.The dilution of inactive gass such as the also available nitrogen of oxygen (oxygen), argon gas, helium, carbonic acid gas.Also can use oxygen-containing gass such as air.Supplying with the method for oxygen-containing gas to reaction system does not have special restriction, can adopt known method.Particularly can suitably use method such as in liquid, bubble.

Above-mentioned reaction form can be continous way, intermittent type, semibatch etc. any, do not have restriction especially.When catalyzer adopts the intermittent reaction form, can add reaction unit with raw material.And the reaction form can be filled in above-mentioned catalyzer reaction unit in advance, or raw material is added reaction unit continuously with catalyzer when adopting continous way.Catalyzer can be any forms such as fixed bed, fluidized-bed, suspension bed.

Secondly, enumerate the reaction formation concrete example.When catalyzer is used for fixing bed, for example can use, (i) with the catalyzer predetermined fixed in reactor, supply with the raw material that is dissolved with oxygen-containing gas continuously to it then, in the reaction solution of extracting out, dissolve oxygen-containing gas again, the outer loop type reactor that refluxes to reactor, (ii) catalyzer is fixed in tube-type reactor, continuously base feed is with the tube-type reactor of oxygen-containing gas, (iii) be filled in catalyzer tower reactor, the spray filler tower reactor of continuous base feed and oxygen-containing gas etc.Wherein, particularly under situation (ii),, supply with, can improve reaction efficiency to many places (reactor inlet, middle part etc.) by cutting apart oxygen-containing gas.And under situation (iii), being external phase by making gas, liquid is disperse phase, can improve reaction efficiency.

When using catalyzer, can use for example (iv) in groove type reactor, to add raw material and catalyzer with suspension bed or fluidized-bed, continuously supply with tank reactor that oxygen-containing gas on one side react on one side.At this moment, both can adopt raw material had been reacted with the intermittent type that catalyzer adds in the early stage, and also can adopt part material continuous or interim semibatch of supplying with in reaction process is reacted.Also can adopt on one side continuously base feed and oxygen-containing gas, on one side extract reaction solution and gas continuously out continous way react.During successive reaction,, can improve reaction efficiency by using the continuous tank reactor that reactor is in parallel or a plurality of series connection are reacted.Also can use (the v) inner reactor that is provided with dividing plate.In the tower reactor, for example have, supply with oxygen-containing gas continuously, the continuous tank reactor of longitudinal type that both convection current contacts are reacted from the tower bottom from continuous base feed in tower top and catalyzer.When using continuous tank reactor, both reaction solution can be directly extracted out, also it reactor can be supplied to once again.(vi) also can use from bubble-column-type reactor of continuous base feed of tower reactor lower part and oxygen-containing gas etc.

Reaction times does not have special restriction, and different, reaction times or residence time (being detained liquid measure/supply liquid measure in the reactor) are 0.5～30 hour usually, are preferably 1～20 hour with imposing a condition.

Various conditions such as temperature of reaction, reaction pressure can be according to as 1 of raw material, suitably decisions such as the kind of 2-glycol or alcohol, catalyst type.Temperature of reaction is generally 0～200 ℃, is preferably 50～180 ℃.By temperature being set in this scope, reaction is carried out more efficiently.Reaction pressure at decompression, normal pressure, add depress all can, be generally 0.05～10MPa (gauge pressure), be particularly suitable in the scope of 0.1～5MPa.And be to suppress by product etc., the pH value of reaction system preferably transfers to pH2～9.For regulating pH, for example alkali metal compound, alkaline earth metal compound (carboxylate salt) can be added in reaction system as additive.

Above-mentioned reaction can be carried out in the presence of solvent.By using solvent, manufacturing purpose product alpha-hydroxycarboxylic ester efficiently sometimes.Spendable solvent is so long as solubilized raw material 1, and 2-glycol or alcohol are difficult for reaction voluntarily and get final product under reaction conditions, and its kind does not have specific limited, can be according to suitably selections such as the kind of raw alcohol, reaction conditionss.For example, outside dewatering, can enumerate ethers such as diethyl ether, diisopropyl ether, diox; Arenes such as toluene, dimethylbenzene, benzene; Halogen-containing compounds such as chloromethane, chloroform, Ethylene Dichloride.Solvent load can suitably be set according to solvent species, pure kind, catalyst type etc.Through this reaction, can obtain containing the resultant of reaction of alpha-hydroxycarboxylic ester.

In the operation 1, also alpha-hydroxy carboxylic acid compounds can be added again and/or the alpha-hydroxy carboxylic acid compounds ester oligomer reacts.Special declaration hereinafter as not, 1, during the pure and mild alcohol reaction of 2-two, alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate also is addible compound.

React by adding particular substrate, can efficiently make alpha-hydroxycarboxylic ester as object.It is the reasons are as follows:

The intramolecularly of alpha-hydroxycarboxylic ester has hydroxyl and ester group, is the hyperergy compound, has the feature that is easy to take place side reaction in reactor after generating.For example, alpha-hydroxycarboxylic ester carries out transesterification reaction mutually, forms the alpha-hydroxy carboxylic acid compounds ester oligomer sometimes.And 1, during the pure and mild alcohol reaction of 2-two, sometimes, alpha-hydroxycarboxylic ester with as 1 of raw material, 2-glycol generation transesterification reaction forms alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate.And, owing in the reaction water byproduct is arranged, so make the alpha-hydroxycarboxylic ester hydrolysis and generate alpha-hydroxy carboxylic acid compounds by this water.Because this side reaction under any circumstance, all can make the alpha-hydroxycarboxylic ester growing amount of being hoped reduce.And the alpha-hydroxy carboxylic acid compounds that hydrolysis generates in the presence of water plays the effect of the acid catalyst of above-mentioned side reaction, thereby has further promoted side reaction.But above-mentioned side reaction is balanced reaction.Therefore, in reactor, add alpha-hydroxy carboxylic acid compounds and/or the alpha-hydroxy carboxylic acid compounds ester oligomer (1 suitable with the side reaction resultant, when 2-glycol and alcohol react, option also comprises alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate, down together), make its coexistence, just can reduce the apparent speed of response of above-mentioned side reaction, suppress side reaction.

The alpha-hydroxy carboxylic acid compounds ester oligomer is the polycondensate through alpha-hydroxycarboxylic ester and/or the connection of alpha-hydroxy carboxylic acid compounds ester bond.For example, comprise that oligopolymer do not hold the alpha-hydroxy carboxylic acid compounds ester oligomer into the ester of alcohol, oligopolymer does not hold alpha-hydroxy carboxylic acid compounds-2-hydroxyl ethyl ester oligopolymer, the oligopolymer for the ester of ethylene glycol not hold hydrolysis to form the alpha-hydroxy carboxylic acid compounds oligopolymer of carboxylic acid.

Oligopolymer is with-O-CH ₂-C-(=O)-expression 2 above bonded products of repeating unit, its upper limit is not had specific limited.But when repeating unit is too much, then may makes reactive reduction or fusing point rising or viscosity rising and cause difficult the processing, so the repeating unit upper limit is preferably below 100.

The addition of alpha-hydroxy carboxylic acid compounds and/or alpha-hydroxy carboxylic acid compounds ester oligomer is preferably with respect to raw material 1, and the 2-glycol is 0.1 mole more than the %, more preferably 0.3 mole more than the %.

Alpha-hydroxy carboxylic acid compounds that is added and/or alpha-hydroxy carboxylic acid compounds ester oligomer can be mixed into before reaction in the reaction raw materials, also can add in reaction.Situation is supplied with operation 1 by liquid at the bottom of the distillation Tata that contains byproduct of reaction that will generate in operation 1 and/or the operation 2 as described later in detail, also can be used as the interpolation of above-mentioned particular substrate.

[operation 2]

In operation 2,, isolate alpha-hydroxycarboxylic ester by operation 1 gained resultant of reaction is under reduced pressure distilled.Reduced pressure does not have specific limited, is generally 1～100000Pa, is preferably 13～80000Pa.By underpressure distillation, reduce temperature in the distillation tower, can suppress side reaction in the tower.

In the operation 1 gained resultant of reaction, except that purpose resultant alpha-hydroxycarboxylic ester, also contain unreacted 1,2-glycol, alcohol, water byproduct etc.By distillation reaction resultant under reduced pressure, separablely go out alpha-hydroxycarboxylic ester.

During distillation, under reduced pressure the straight run distillation resultant of reaction also can distill after other operation.So-called other operation can enumerate solids component such as separating catalyst for example separation circuit, remove low boiling point component evaporization process, be used for the by product of reaction solution is changed into the reaction process of effective constituent, adjusted the distillation pretreatment procedure of reaction solution composition etc. for stable distillation.

Distillating method can be the rectifying of using simple distillation or multistage distillation tower, preferably carries out rectifying.The distillation mode can suitably adopt in intermittent type, the continous way any.

When using the multistage distillation tower, the distillation tower stage number does not have specific qualification, and preferably the stage number except that (orlop) at the bottom of cat head (the superiors) and the tower is more than 2 grades.This distillation tower can use and be filled with the packing tower that Raschig ring, Pall ring, Intalox saddle(packing), Charles Dixon formula filler, Mai Kema flood formula filler, Suhl are adopted filler such as filler; Bubble cap tray, sieve plate, valve tray etc. use distillation towers commonly used such as the tray column of column plate.Also can use the combined type distillation tower that has column plate and packing layer concurrently.The a plurality of multistage distillation towers of use also capable of being combined.And above-mentioned stage number is represented stage number in tray column, and in packing tower, then the representation theory stage number.

Method to fractionation by distillation alpha-hydroxycarboxylic ester from resultant of reaction does not have specific limited.Can select the suitableeest method according to the composition of resultant of reaction.Also available a plurality of distillation towers.At this moment, both low boiling point component can be separated earlier, also the high boiling point composition can be separated earlier.

Resultant of reaction contains composition and the high boiling point composition lower than alpha-hydroxycarboxylic ester boiling point, when separating alpha-hydroxycarboxylic ester by continuous still battery, preferably from the distillation tower stage casing alpha-hydroxycarboxylic ester is extracted out with side stream.Because alpha-hydroxycarboxylic ester causes side reaction because of heating, so, extract out from the distillation tower stage casing, and can in the inhibition side reaction, distill by at the bottom of avoiding making it to drop down onto the high tower of temperature.Be to suppress side reaction, preferably be supplied in contained alpha-hydroxycarboxylic ester in the resultant of reaction of distillation tower, with side stream extract out wherein more than 50%.

When carrying out the side line fractionation,, remove this and do not have special restriction, can adopt the common structure that possesses reboiler, condenser etc. as long as the structure of distillation tower has the side line fractionation partly.Side line fractionation part preferably is located at the position that is distributed with the higher concentration alpha-hydroxycarboxylic ester in the distillation tower.This position can suitably be located at the bottom of the tower and position outside the cat head according to the composition of used mixture, distillation condition (mixture supply column plate) etc.For example, for further reducing by the low boiling point component in the side line fractionation gained alpha-hydroxycarboxylic ester, preferably carry out the side line fractionation, and, preferably carry out the side line fractionation from the more upper strata that is higher than mixture supply column plate for further reducing the high boiling point composition from the more lower floor column plate that is lower than mixture supply column plate.And be to obtain more highly purified alpha-hydroxycarboxylic ester by the side line fractionation, also can use combined type distillation towers such as bernoulli formula distillation tower.By adopting such structure, can distinguish 1) from cat head, propose to contain the cut, 2 that concentrates low boiling point component) extract the cut, 3 that contains alpha-hydroxycarboxylic ester from side line fractionation portion) at the bottom of tower, extract the liquid that is rich in the high boiling point composition.

And, as described below, from resultant of reaction, remove and anhydrate, when unreacting material is supplied with other operation, also can in operation 2, dewater.Water both can be extracted out from the distillation tower cat head with low-boiling point alcohol, by redistillation water was separated with alcohol; Also can use 1 distillation tower, two place's side line fractionating tubes are set, extract alcohol out by cat head respectively, extract water out, extract alpha-hydroxycarboxylic ester out, by extracting 1 out at the bottom of the tower, the 2-glycol by the side line fractionation of the 2nd place by the side line fractionation of the 1st place.

And the low boiling point component ratio in resultant of reaction for a long time, also can distill after having reduced the low boiling point component amount by implement operations such as flash distillation, evaporation before distillation.

And be the side reaction that suppresses in the distillation tower, preferably reduce the thermal history of reaction solution in distillation tower as far as possible.As the device that is used for heating liquid, preferably can reduce the devices such as liquid film type reboiler of thermal history.Particularly, in when distillation, preferably contact with hot face and heat this resultant of reaction by making resultant of reaction be film like.Above-mentioned heating can be implemented by for example using the liquid film type evaporating kettle that can reduce thermal history.The liquid film evaporation still limits especially, for example can use well known devices such as rising liquid film type, liquid falling film type, stirring liquid film type.Heating condition can be according to known condition.Therefore,, make the liquid that contains resultant of reaction, heat with film like Contact Heating face by supplying with the liquid that contains resultant of reaction to the liquid film type evaporating kettle.Thus, can shorten the heat-up time of resultant of reaction, the result just can effectively suppress the side reaction of alpha-hydroxycarboxylic ester.

In the present invention, for obtaining purity height, good, the painted few goods of yield, working pressure, column bottom temperature in the distillation tower during the distillation alpha-hydroxycarboxylic ester are very important.For suppressing the side reaction in the distillation tower,, can suppress side reaction by in the pressure range of 13～80000Pa, distilling.And distill under 30～250 ℃ by column bottom temperature is adjusted into, can suppress side reaction.

In addition, the distillation tower trim the top of column than without limits, is preferably 0.1～100, more preferably 0.3～50.Other operational condition gets final product according to known distillation condition.

By aforesaid distillation, can separate alpha-hydroxycarboxylic ester by the resultant of reaction that operation 1 obtains.

As mentioned above, alpha-hydroxycarboxylic ester is that intramolecularly has hydroxyl and ester group, reactive high compound, and heating during by reaction, distillation easily causes side reaction.For example, by carrying out transesterification reaction between the alpha-hydroxy carboxylic acid compounds ester molecule, form the oligopolymer that the alpha-hydroxy carboxylic acid compounds ester molecule connects by a plurality of ester bonds sometimes.With the ester group-C of alpha-hydroxycarboxylic ester (=O) during the alcohol coexistence outside the corresponding R-OH of OR, cause this pure and mild transesterification reaction sometimes, generation has the alpha-hydroxycarboxylic ester of different ester groups.And when water coexisted, the alpha-hydroxycarboxylic ester hydrolysis generated alpha-hydroxy carboxylic acid compounds.By these side reactions, under any circumstance all will reduce the alpha-hydroxycarboxylic ester of being hoped.In addition, in the presence of water, the alpha-hydroxy carboxylic acid compounds that hydrolysis generates is a carboxylic acid, pretends to the acid catalyst of above-mentioned side reaction and has an effect, and has further promoted above-mentioned side reaction.Particularly in reaction process of the present invention (operation 1),, produce 2 mol of by-products water,, be very easy to cause above-mentioned side reaction so when distillation reaction liquid, be very easy to take place hydrolysis with respect to 1 mole of alpha-hydroxycarboxylic ester.

Moreover above-mentioned side reaction is ester group-C (=O) the pure R-OH free reaction of OR (but R is organic residue) corresponding to alpha-hydroxycarboxylic ester.Therefore, this alcohol is during than the lower low boiling point component of alpha-hydroxycarboxylic ester boiling point, should preferentially be heated up in a steamer by alcohol in still-process, and the result has destroyed the balance of side reaction, and side reaction is further carried out.

For preventing or suppressing this class side reaction (during distillation, when reacting), for example preferably liquid at the bottom of the distillation Tata that comprises at least a kind of byproduct of reaction that is selected from alpha-hydroxy carboxylic acid compounds and alpha-hydroxy carboxylic acid compounds ester oligomer that generates in the operation 2 is supplied to operation 1 and/or operation 2.It can prevent or suppress the explanation in operation 1 of side reaction reason.In addition, liquid is meant by liquid at the bottom of the distillation Tata behind fractionation by distillation (heating up in a steamer) alpha-hydroxycarboxylic ester at the bottom of the distillation Tata.Liquid can directly utilize at the bottom of this tower, also can utilize than liquid at the bottom of the higher high boiling fraction of distillation gained alpha-hydroxycarboxylic ester boiling point or this tower.

By aforesaid distillation, contain by product alpha-hydroxy carboxylic acid compounds that alpha-hydroxycarboxylic ester reaction process and distillation process generate, alpha-hydroxy carboxylic acid compounds ester oligomer etc. at the bottom of the distillation Tata after alpha-hydroxycarboxylic ester heats up in a steamer in the liquid.Also can contain compositions such as alpha-hydroxycarboxylic ester, unreacting material in the liquid at the bottom of the tower.

Liquid is supplied to operation 1 and/or operation 2 at the bottom of this tower.As mentioned above, the side reaction in operation 1 and the operation 2 is balanced reaction.Therefore, contain liquid at the bottom of the tower of byproduct of reaction by supply, in reaction process and/or distillation process, contain byproduct of reaction at the very start, delay on the formation speed of this new by product is apparent.As a result, in reaction process, improved the yield of alpha-hydroxycarboxylic ester, and in distillation process, improved the purification efficiency of alpha-hydroxycarboxylic ester.According to liquid measure at the bottom of the tower of supplying with, contained at least a kind of byproduct of reaction and the raw alcohol reaction that is selected from alpha-hydroxy carboxylic acid compounds, alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl and alpha-hydroxy carboxylic acid compounds ester oligomer in the liquid at the bottom of the tower, generate the alpha-hydroxycarboxylic ester of being hoped, and more help to improve the yield in the reaction process, the refining yield in the raising distillation process.And, utilize again owing to byproduct of reaction can be used as effective constituent, so the effect of cutting down the refuse amount is also arranged.

In addition, liquid also can directly not be supplied to operation 1 and/or operation 2 at the bottom of the tower, and is contacting once back supply with raw alcohol.Raw alcohol is meant ester group-C corresponding to alpha-hydroxycarboxylic ester (=O) pure R-OH of OR (but R is organic residue).At this moment, by alcohol and the contacting of liquid at the bottom of the tower, by esterification, the alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate and the transesterification reaction of alcohol and the alcoholysis reaction of alpha-hydroxy carboxylic acid compounds ester oligomer of alpha-hydroxy carboxylic acid compounds with alcohol, generation alpha-hydroxycarboxylic ester.

Because of above-mentioned reaction is balanced reaction, pure consumption can obtain alpha-hydroxycarboxylic ester by high yield more at most.It is relevant that alcohol consumption and liquid at the bottom of the tower are formed, and is preferably with more than the liquid weight at the bottom of the tower etc. times, more preferably more than the twice.Temperature of reaction is preferably 30 ℃～200 ℃, more preferably 40 ℃～180 ℃.In the time of below 30 ℃, speed of response is slow, and efficient is poor; Might cause side reaction and surpass 200 ℃.

And contact with raw alcohol when reacting at liquid at the bottom of the tower, also can use catalyzer.Catalyzer can be enumerated for example acid, alkali, metallic compounds such as titanium, lead, tin.Wherein be preferably acid.Acid catalyst can be enumerated for example homogeneous catalysts such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, heteropolyacid, tosic acid, acetic acid; Heterogeneous catalyst such as acidic ion exchange resin, zeolite, clay.Wherein, according to isolating difficulty or ease, be preferably heterogeneous catalyst.

Can be supplied to reaction process (operation 1) with liquid at the bottom of the tower of alcohol reaction back, also can be supplied to distillation process (operation 2), reclaim by distillation and the ethyl glycolate that the alcohol reaction generates.

In the alpha-hydroxycarboxylic ester, ethyl glycolate also can be by the reduction of oxalate diester, oxidation of glycol esterification etc. is synthetic as described in the present invention.But in reduction during oxalate diester, obtain the unreacted oxalate diester and mix the resultant of reaction that exists as the ethyl glycolate of resultant.During the oxidation of glycol esterification, when ethylene glycol two terminal generation oxidisability esterifications are reacted, then can obtain the by product oxalate diester.Ethyl glycolate and oxalate diester boiling point are approaching, and the vapor liquid equilibrium curve levels off to the straight line of Y=X, so be difficult to by fractionation by distillation, are difficult to obtain the low high purity ethanol acid esters of oxalate diester content.

The inventor etc. are after the separating of the ethyl glycolate of having studied fractionation by distillation and oxalate diester, and the result draws following conclusion.

At first, find oxalate diester and water azeotropic.In the presence of water during the mixture of distillation ethyl glycolate and oxalate diester, the oxalate diester in the distillation tower and water azeotropic and be distributed in the ethyl glycolate top, the energy high efficiency separation.As a result, compare, can obtain the low ethyl glycolate of oxalate diester content with anhydrous situation.

Secondly, oxalate diester is easy to hydrolysis than ethyl glycolate, and when distilling in the presence of water, hydrolysis takes place in distillation tower oxalate diester, forms oxalic acid monoesters and oxalic acid.Oxalic acid monoesters and oxalic acid is because of having carboxyl boiling point height, cause and ethyl glycolate between boiling-point difference increase, so can obtain the low ethyl glycolate of oxalate diester content by distillation.

Oxalate diester is compared with ethyl glycolate, easily with the alcohol that is different from the alcohol that constitutes ester group (being called other alcohol down) transesterification reaction takes place, and when distilling under coexisting with other alcohol, barkite forms other pure ester.Other pure boiling point is lower than when constituting ester group pure, and the boiling point of the barkite that generates because of transesterify becomes and is lower than ethyl glycolate, therefore is easy to separate.Otherwise other pure boiling point is higher than when constituting ester group pure, and the boiling point of the barkite that generates because of transesterify becomes and is higher than ethyl glycolate, and is easy to separate.

In addition, as mentioned above, by distillation ethyl glycolate and oxalate diester mixture in the presence of water and/or other alcohol, discovery can obtain the poor high purity ethanol acid esters of oxalate diester.

As specify this technology, then when for example making methyl glycolate by methyl alcohol and ethylene glycol by the oxidisability esterification, the ethylene glycol two ends of by product generate and cause oxidisability esterification reaction dimethyl oxalate.Methyl glycolate is close with the dimethyl oxalate boiling point, and the straight line of vapor liquid equilibrium curve convergence Y=X is so be difficult to pass through fractionation by distillation.But in this oxidisability esterification reaction solution, contain water byproduct, with alcohol---alcohol that methyl alcohol the is different---ethylene glycol that constitutes dimethyl oxalate etc.Therefore, when this reaction solution of distillation,, separate as the cut lighter than ethyl glycolate by part dimethyl oxalate and water azeotropic.And the part dimethyl oxalate is subjected to hydrolysis and forms oxalic acid mono-methyl, oxalic acid etc. in distillation tower, becomes the component that overweights ethyl glycolate and by extracting out at the bottom of the tower.And the part dimethyl oxalate in distillation tower with ethylene glycol generation transesterification reaction, generate heavy components such as oxalic acid-2-hydroxyethyl methyl esters, oxalic acid two-2-hydroxyl ethyl ester.These heavy component boiling points are higher than methyl glycolate, extract out at the bottom of tower.

Like this, when ethyl glycolate is made in oxidisability esterification reaction according to the present invention, compare with other method for making, easier of distillation manufacturing high purity ethanol acid esters.

(operation 3)

In operation 3, from operation 1 gained resultant of reaction, remove part or all of water, will contain 1 of end reaction, the mixture of 2-glycol and/or alcohol is supplied to operation 1.

In alpha-hydroxycarboxylic ester synthetic, do not reach at 100% o'clock at feed stock conversion, unreacting material is present in the operation 1 gained resultant of reaction.Therefore, by remove part or all of water from operation 1 gained resultant of reaction, will contain unreacted 1, the mixture of 2-glycol and/or alcohol is supplied to operation 1, just can efficiently make alpha-hydroxycarboxylic ester.Removing the method for part or all of water does not have specific limited, and known methods such as for example available distillation, extraction are removed.

And operation 3 can be used operation 1 gained resultant of reaction itself resultant of reaction of operation 2 (promptly without), or any one of resultant of reaction (promptly through operation 2, separating the resultant of reaction behind the alpha-hydroxycarboxylic ester) of having passed through operation 2 carried out.Also can carry out simultaneously with operation 2.

When resultant of reaction was removed part or all of water, the mixture that is supplied to operation 1 was preferably removed all or part of water and is transferred to moisture 0～20 quality %.Be supplied to the water content in the mixture of operation 1, only supplying with unreacted 1, during the 2-glycol, be meant to contain unreacted 1, the water content in the mixture of 2-glycol; And when only supplying with unreacting alcohol, be meant the water content in the mixture that contains unreacting alcohol; Both supplying with unreacted 1, when the 2-glycol is supplied with unreacting alcohol again, referring to that then each mixture adds up to the water content aggregate value in each shared mixture.When operation 1 was supplied with the mixture that contains the water that surpasses 20 quality %, the alpha-hydroxycarboxylic ester that reaction generates might reduce the alpha-hydroxycarboxylic ester yield with hydrolysis.And, might generate water and carbonic acid gas to the further oxidation of alpha-hydroxy carboxylic acid compounds that hydrolysis generates.

And the water yield of from resultant of reaction, removing, different because of the setting of the water content of the mixture of supplying with operation 1, preferably remove usually more than the aqueous 30 quality % of resultant of reaction institute.

During unreacting material supply response operation (operation 1), because of reaction consumes, the part of being lost when refining is appended to base feed with the new raw material of a great deal of and reacts.By supplying with this unreacting material, when operation 1～3 was stable state, preferably control removed water condition in operation 3, made that the whole water content of reaction raw materials is 0.1～15 quality % in the operation 1.What stable state was represented is to react, distill when all carrying out with continous way, and each operation component is close to certain state; Or react, distill and all carry out with intermittent type, operation 1～3 is a circulation time, is meant after the 4th circulation.

Secondly, embodiment of the present invention is described with reference to the accompanying drawings.For example, reactor uses two continous ways to stir tank reactor, and distillation tower uses the distillation tower with 2 places side line fractionation extraction unit, makes 1, and the 2-glycol is made alpha-hydroxycarboxylic ester with the alcohol reaction, according to Fig. 1 this situation is described.

As shown in Figure 1, reaction unit comprises continous way stirred tank reactor 11,12, distillation tower 13. Reactor 11 and 12 all possesses whipping appts, heating unit.Reactor 11 is connected with raw material supplying pipe 21, and the top of tank reactor 11 is connecting conduit 24 continuously.Conduit 24 has the function of the raw material supplying pipe of reactor 12.The top of reactor 12 is connected with conduit 25, resultant of reaction can be imported in the distillation tower 13.The distillation tower stage casing is provided with the extraction pipe 28 and 29 that can extract liquid by the side line fractionation out.And the cat head of distillation tower 13 is connected by conduit 26 with raw material supplying pipe 21, and what formation can make distillation tower 13 distillates component Returning reactor 11.

As 1 of reaction raw materials, 2-two pure and mild alcohol pass through raw material supply tube 21 continuously to reactor 11 chargings.Catalyzer can add reactor in advance, also can supply with simultaneously with raw material.This reaction solution limit heating is stirred on the limit then, under design temperature, setting pressure condition, on one side to reaction solution air supply (oxygen-containing gas) reaction on one side, synthetic alpha-hydroxycarboxylic ester.

Surpass the reaction solution of setting the liquid level part, import reactor 12 by conduit 24 and continue reaction.When in suspension bed, using catalyzer, be suspended with the reaction solution of catalyzer, in solid-liquid separation tank (not having diagram), separate, only reaction solution is imported reactor 12.Reactor 12 continues to keep preset temperature, reacts through air supply pipe 23 air supplies (oxygen-containing gas).Surpass the reaction solution of setting the liquid level part, extract out through conduit 25.

Having heaters at the bottom of distillation tower 13 towers (not having diagram), cat head have condenser (not having diagram), and the part overhead fraction of condensation can be refluxed.Through the reactor of conduit 25 to distillation tower 13 feed, in distillation tower 13, separate with vapor liquid equilibrium, extract unreacting alcohol out from cat head respectively, extract pipe 28 out from the stage casing side stream and extract water generation reaction out, extract pipe 29 out from the stage casing side stream and extract the resultant alpha-hydroxycarboxylic ester out, at the bottom of tower, extract unreacted 1 out, 2-diol by-product alpha-hydroxy carboxylic acid compounds, alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate and alpha-hydroxy carboxylic acid compounds ester oligomer etc.

The alcohol of extracting out from cat head imports reactor 11 circulations as unreacting material through conduit 26.And extract out at the bottom of the tower 1, the 2-glycol imports reactors 11 circulations as unreacting material through conduit 27 too.At this moment, by while round-robin alpha-hydroxy carboxylic acid compounds, alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate and alpha-hydroxy carboxylic acid compounds ester oligomer, but the side reaction in inhibited reaction device 11 and 12.When unreacting material alcohol and/or 1,2-glycol circulation time replenishes and the raw material that loses the part a great deal of because of reaction consumes, when making with extra care through raw material supplying pipe 21.

Along with the sustainable supply of unreacting material, when by product is accumulated in system, according to the boiling point of by product, can be at the bottom of wash tube 30 and 31 be extracted overhead fractions or tower out the part of liquid.

And, extract pipe 28 out through side stream, can extract part or total overall reaction water byproduct out, can reduce the water content in the unreacting material of being supplied with, and the alpha-hydroxycarboxylic ester yield reduces in the energy inhibited reaction.

2. alpha-hydroxy carboxylic acid compounds class condenses

Alpha-hydroxy carboxylic acid compounds class condenses of the present invention has shown in following (I)～(III) three kinds.

(I) for containing the alpha-hydroxy carboxylic acid compounds class condensation part shown in the following general formula (2) with shown in the following general formula (3) 1, the alpha-hydroxy carboxylic acid compounds class condenses of 2-glycol chains, its two ends are the alpha-hydroxy carboxylic acid compounds class condenses shown in following general formula (4) or the following general formula (5),

In general formula (2),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (3),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (4),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (5),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

(II) be the alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (6),

In general formula (6), R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group, and the scope of n is 1～200;

(III) be the alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (7),

In general formula (7), R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group, and n1, n2 are all more than 1, and the scope of n1+n2 is 2～200.

In the general formula (2) of the structural unit of representing alpha-hydroxy carboxylic acid compounds class condenses of the present invention, R represents the alkyl of hydrogen or carbonatoms 1～5.And R can be different at intramolecularly.Alkyl also can have substituting group.When for example R was hydrogen, alpha-hydroxy carboxylic acid compounds class condenses was an ethanol acids condenses, and R is a lactic acid class condenses during for methyl.Equally, in general formula (3), R represents the alkyl of hydrogen or carbonatoms 1～5.R can be different at intramolecularly.Alkyl also can have substituting group.When R was hydrogen, general formula (3) was a glycol chain, and R is the propylene glycol chain during for methyl.The present invention includes the structural unit of above-mentioned general formula (2) and (3), two is not auspicious for containing the alpha-hydroxy carboxylic acid compounds class condenses of above-mentioned general formula (4) or (5).Therefore, the two ends of this condenses have hydroxyl.

And alpha-hydroxy carboxylic acid compounds class condenses of the present invention also can contain the composition outside the structural unit outside above-mentioned general formula (2) and (3), also can be the multipolymer with other composition.Copolymer composition can be enumerated for example oxalic acid, propanedioic acid, succsinic acid, pentanedioic acid, hexanodioic acid, 1, dicarboxylic acid or 1 such as 4-cyclohexane diacid, diethyl alkyd, glycol such as 4-cyclohexanedimethanol, Diethylene Glycol, triethylene glycol.

In alpha-hydroxy carboxylic acid compounds class condenses of the present invention, structural unit proportion shown in the general formula (2) is preferably more than the 70 quality %, more preferably more than the 80 quality %, more preferably more than the 90 quality %.

Because alpha-hydroxy carboxylic acid compounds class condenses of the present invention contains alpha-hydroxy carboxylic acid compounds class condensation part and 1, the 2-glycol chains, its main chain contains a large amount of 2 carbon atom bonded unit, is rich in crystalline high-density condenses so can make.

The having more style and can enumerate the alpha-hydroxy carboxylic acid compounds class condenses shown in the general formula (6) and do not hold into 1, the condenses of 2-diol ester (condenses (II)) of alpha-hydroxy carboxylic acid compounds class condenses of the present invention.In the formula, R represents the alkyl of hydrogen or carbonatoms 1～5.R can be different at intramolecularly.Alkyl can have substituting group, and the scope of n is 2～200.

Also can enumerate 1 shown in the general formula (7), 2-glycol two ends are combined with the condenses (condenses (III)) of alpha-hydroxy carboxylic acid compounds class condenses.In the formula, show the alkyl of hydrogen or carbonatoms 1～5.R can be different at intramolecularly.Alkyl can have substituting group, and n1, n2 are all more than 1, and the scope of n1+n2 is 2～200.

By making these alpha-hydroxy carboxylic acid compounds class condensess possess hydroxyl at two ends, the effect of performance chain extension agent is sought polymer easily and is quantized.When polymer quantizes, can use common chain extension agent.The chain extension agent can be enumerated for example multi-anhydride, polycarboxylic acid, polynary ester, multicomponent isocyanate, Duo Guan Neng oxazoline compound, multifunctional ethylenimine, carbonate products, epoxy compounds, organosilane coupler, phosphoric acid ester, phosphorous acid ester, zinc alkyl(s), aluminum alkyls etc.

These alpha-hydroxy carboxylic acid compounds class condensess of the present invention are as the raw material of various synthetic resins, industrial be very useful compound.

The manufacture method of condenses (I)～(III)

A. manufacture method general introduction

Alpha-hydroxy carboxylic acid compounds class condenses (I)～(III) can pass through with following general formula (8)

Shown alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate takes off 1, and 2-glycol reaction condensation makes.In the formula, R represents the alkyl of hydrogen or carbonatoms 1～5.Alkyl can have substituting group.

In general formula (8), when for example R was hydrogen, general formula (8) was an oxyacetic acid 2-hydroxyl ethyl ester, and by product 1,2-glycol are ethylene glycol.When R was methyl, general formula (8) was a lactic acid 2-hydroxypropyl acrylate, and by product 1,2-glycol are 1, the 2-propylene glycol.

In this reaction, can use the R difference of general formula (8), a plurality of alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate as raw material.

Because the hydroxyl of the hydroxycarboxylic acid of the alpha-hydroxycarboxylic ester of general formula (8) part is present in the α position, can not cause side reactions such as intramolecular dehydration during reaction, and condensation reaction between preferential trigger molecule can obtain condenses with high yield.

Temperature of reaction is 70～240 ℃, is preferably 90～230 ℃, more preferably 110～220 ℃.Reaction temperature spends that low then speed of response is too slow, the production efficiency variation; Temperature of reaction is too high, becomes then that the resultant quality increases the weight of, painted etc. former prisoner.And if the initial reaction stage temperature of reaction is too high, have the alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate and distillate, the situation that yield reduces is so temperature of reaction is preferably set to interim the raising.

Not necessarily must use catalyzer in this reaction, be accelerated reaction, also can use catalyzer.Catalyzer can be enumerated for example an acidic catalysts such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, heteropolyacid, tosic acid, methylsulfonic acid, oxyacetic acid, acidic ion exchange resin, zeolite, clay; Tin series catalysts such as tin chloride, tin protochloride, dibutyl tin oxide, stannic oxide, tin protoxide, stannous octoate: Titanium series catalysts such as tetraisopropoxy titanium, titanium tetrachloride; Metal oxide series catalysts such as ANTIMONY TRIOXIDE SB 203 99.8 PCT, plumbous oxide, zinc oxide, aluminum oxide etc.These catalyzer can independent or a plurality of being used in combination.

Because this reaction is balanced reaction, by with 1 of pair life, the 2-glycol can make balance move except that to system, efficiently reacts.

Initial reaction stage, alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate sometimes with pair give birth to 1, the 2-glycol distillates together.At this moment, add backflow because of reactor connects distillation tower, by separating 1,2-glycol and alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate are extracted high purity 1 out, and the 2-glycol can good yield be made alpha-hydroxy carboxylic acid compounds class condenses.

Because 1 of secondary life, 2-glycol boiling point height in order effectively to remove, preferably is adjusted to decompression with system.Pressure is preferably below 0.08MPa, more preferably below 0.06MPa.Also can import inactive gass such as nitrogen, helium, with 1, the 2-glycol is together removed.

Distilled 1, the 2-glycol can utilize by the manufacturing process of following alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate.And 1 of this moment, also can contain distilled alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate in the 2-glycol.

B. condenses is made the manufacture method of raw material

The alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate of making raw material as condenses can be by 1 in the manufacture method of for example alpha-hydroxycarboxylic ester of the invention described above, the reaction manufacturing between the 2-glycol.To 1, the kind of 2-glycol, reaction conditions, explanation of spendable catalyzer etc. is as mentioned above as required.

The alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate that reacts and get can be directly used in the manufacturing condenses, also can use after refining.The refining known methods such as distillation, extraction that can adopt are implemented.

Because of containing boiling point in the above-mentioned reaction solution than low generation water, the unreacted 1 of ester that generates, 2-glycol etc. can heat up in a steamer these low boiling point components through distillation, are the condensation reaction raw material with liquid at the bottom of the tower of remnants.The unreacted 1 that heats up in a steamer, the 2-glycol is recycling in reaction.When distilling continuously, can extract water out from cat head, extract 1 out from side stream, the 2-glycol is extracted the alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate out at the bottom of tower, efficiently distill.

And desire when further refining, can be heated up in a steamer low boiling point component to the alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate that generates as mentioned above, and then distillates the alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate from cat head and also can.At this moment, preferably under reduced pressure, distill.When heating alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate, oligomeric materialization is carried out, and pair bears 1, the 2-glycol.Therefore, might in distilled alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate, sneak into 1,2-glycol, or the refining yield of reduction alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate.By reducing temperature in the distillation tower under the decompression, can suppress oligomeric materialization.Pressure is preferably below 80000Pa.

Description of drawings

Fig. 1 has the schema that continous way stirs the reaction unit example of tank reactor.

Fig. 2 is the FT-IR figure of embodiment 7-2 gained alpha-hydroxy carboxylic acid compounds class condenses.

Fig. 3 is an embodiment 7-2 gained alpha-hydroxy carboxylic acid compounds class condenses ¹H-NMR figure.

Nomenclature:

11,12: reactor; 13: distillation tower; 21: the raw material supplying pipe; 22,23: air supply pipe; 28,29: side stream is extracted pipe out.

Embodiment

Below, with embodiment and comparative example the present invention is made more specific description.But the present invention is not limited by embodiment.

And the physical property measurement in embodiment, comparative example and the reference example etc. according under show that method implements.

(1) metal particle loading amount: measure according to the fluorescent X-ray analysis

(2) median size of metal particle: observe particle diameter with transmission electron microscope (TEM) (device name " HF-2000 " Hitachi, acceleration voltage 200kV), with accessory x-ray analysis equipment analysing particulates composition.

(3) resultant of reaction is quantitative: with the resultant of reaction composition in gas chromatograph and/or the liquid chromatograph quantitative analysis reaction solution.

Reference example 1 (Au/TiO ₂-SiO ₂The modulation of catalyzer)

Will be with the synthetic TiO of coprecipitation method ₂-SiO ₂(mol ratio TiO ₂/ SiO ₂=5/95,600 ℃ of firing temperatures, 50～250 orders) as carrier.In 65～75 ℃ scope, the tetra chlorauric acid 40L of concentration 20mmol/1 is adjusted to pH7 with the 0.5N sodium hydroxide solution.Under agitation in this aqueous solution, drop into above-mentioned TiO ₂-SiO ₂Carrier 1kg when keeping 65～70 ℃ of temperature, continues to stir 1 hour.Then, remove supernatant liquor after leaving standstill, in residual golden fixed compound, add ion exchanged water 20L, at room temperature stir 5 minutes after, repeat to remove the matting 3 times of supernatant liquor.At last will be after filtration gained golden fixed compound 110 ℃ dry 8 hours down, in air, fired under 400 ℃ 3 hours again, obtain TiO ₂-SiO ₂Be carried with the catalyzer (Au/TiO of gold on the carrier ₂-SiO ₂).

The loading amount with respect to the gold of carrier in this catalyzer is 5.4 quality %.And after observing the particle diameter of gold grain, the gained result is, almost all with the particle diameter high dispersing below the 6nm, has the narrow size distribution that maximum value is arranged near 2～3nm, and median size is below the 6nm.

Embodiment 1-1 (synthesizing of methyl glycolate)

Use derives from the Au/TiO of reference example 1 ₂-SiO ₂Catalyzer synthesizes alpha-hydroxycarboxylic ester (methyl glycolate).

In possessing the 100L reactor of gyratory shaker and condenser, add the catalyzer 4.3kg of ethylene glycol 9.6kg, methyl alcohol 50.0kg and reference example, with nitrogen pressure to 0.7MPa.After this with interior temperature rise to 120 ℃, pressure is transferred to 1MPa.Pressure keeps 1MPa, is blown into air with the flow of 2.5Nm3/hr in liquid, 120 ℃ of reactions 8 hours down.

After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph, liquid chromatograph and Ka Er-Fei Xieshi moisture content tester analytical reaction liquid.Contain methyl glycolate 7.5kg in the reaction solution, ethylene glycol 3.5kg, methyl alcohol 43.2kg, water 4.9kg, oxyacetic acid 0.7kg, ethylene glycol transformation efficiency are 63.5 moles of %, the yield of the methyl glycolate of ethylene glycol benchmark is 53.8 moles of %.

Above-mentioned reaction solution is added thinfilm rotary evaporator, remove low boiling point component.Under 140 ℃ of bushing temperatures, pressure 533hPa, remove low boiling point component.Gained lower boiling side stream liquid consist of methyl glycolate 47.0 quality %, methyl alcohol 26.0 quality %, water 17.0 quality %, ethylene glycol 7.0 quality %, oxyacetic acid 2.6 quality %.

Gained lower boiling side stream liquid 3050g is incorporated in to possess filled the high Sumitomo/Suhl of 90cm and adopt in the 3L glass flask of distillation tower of filler, carry out batch distillation.At first under reflux ratio 0.5, tower top pressure 133hPa, remove the first alcohol and water of low boiling point component.Then, under reflux ratio 1, tower top pressure 13hPa, extract the cut that contains methyl glycolate out.This moment, tower top temperature was 46～47 ℃.Analyze the cut that gained contains methyl glycolate, the result contains methyl glycolate 98.9 quality %, methyl alcohol 0.10 quality %, water 0.31 quality %.

Embodiment 1-2

With the rotary film distillator distilled low boiling component of embodiment 1-1, the initial fraction during with the distillation methyl glycolate adds at the bottom of the tower, carries out batch distillation with 15 grades of Ao Erdexiu (Oldershaw) distillation tower.In 1 time running of reflux ratio, obtain the cut of methyl alcohol 97 quality %, water 3 quality % from cat head.

The catalyzer 18.0g that in having the 500mL autoclave of rotation mixer and condenser, adds ethylene glycol 24.1g, above-mentioned distillation gained cut 127.8g and reference example 1, with nitrogen pressure to 0.7MPa.Water content in the raw material is 2.5 weight %.With interior temperature rise to 120 ℃, pressure transfers to 1MPa then.Pressure keeps 1MPa, and the mixed gas of oxygen 8 volume %, nitrogen 92 volume % is blown into liquid with the flow of per minute 1 standard liter (normal liter), 120 ℃ of reactions 4 hours down.

After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph and liquid chromatograph analytical reaction liquid.Contain methyl glycolate 19.9g, ethylene glycol 3.9g, methyl alcohol 114.2g in the reaction solution, the ethylene glycol transformation efficiency is 83.7 moles of %, and the methyl glycolate yield of ethylene glycol benchmark is 56.9 moles of %.

Comparative example 1

In possessing the 500ml autoclave of gyratory shaker and condenser, add ethylene glycol 24.1g, initial fraction (the moisture 37 quality %) 198g when adding methyl glycolate rectifying among the embodiment 1-1 and the catalysis of reference example 1 cuts open 18.0g, with nitrogen pressure to 0.7MPa.Water content in the raw material is 33 quality %.After this with interior temperature rise to 120 ℃, pressure transfers to 1MPa.Pressure keeps 1MPa, and the mixed gas of oxygen 8 volume %, nitrogen 92 volume % is blown into liquid with the flow that per minute 1 standard rises, 120 ℃ of reactions 4 hours down.

After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph and liquid chromatograph analytical reaction liquid.Contain methyl glycolate 13.8g, ethylene glycol 4.3g and methyl alcohol 115.3g in the reaction solution, the ethylene glycol transformation efficiency is that the methyl glycolate yield of 82.2 moles of %, ethylene glycol benchmark is 39.4 moles of %.

Embodiment 2-1

Refining embodiment 1-1 gained reaction solution.

Water distilling apparatus uses the device that is equipped with rotary film evaporator at the bottom of the distillation Tata of the Charles Dixon formula filler be filled with theoretical plate number 5.Supply with above-mentioned reaction solution continuously to this water distilling apparatus.In tower top pressure 66.7kPa, 1 time running of reflux ratio, contain the mixture of first alcohol and water as liquid of top of the tower from the cat head extraction.And liquid at the bottom of the tower is supplied with same water distilling apparatus once again, carry out the 2nd distillation, liquid (liquid at the bottom of the 2nd tower) at the bottom of extraction liquid of top of the tower (the 2nd liquid of top of the tower) and the tower.This moment, tower top pressure was that 13.3kPa, reflux ratio are 1.

Analyze liquid at the bottom of the 2nd liquid of top of the tower and the 2nd tower respectively with gas chromatograph and liquid chromatograph.The purity of the methyl glycolate of the 2nd liquid of top of the tower is 98 quality %.And in the methyl glycolate of supplying with for the 1st time, what be contained in the 2nd liquid of top of the tower is 83%, and what be contained in liquid at the bottom of the 2nd tower is 16%, and the loss component is 2%.Compare with the by product of the reaction solution that is contained in supply, the contained by product of liquid has increased by the oxyacetic acid 2-hydroxyl ethyl ester of 1 mole of %, the methyl glycolate dimer of 1 mole of % with respect to the methyl glycolate of supplying with at the bottom of the 2nd tower.

Embodiment 2-2

Refining embodiment 1-1 gained reaction solution.

Water distilling apparatus uses the flask device that is equipped with available manual heating device heating at the bottom of the distillation Tata of the Charles Dixon formula filler be filled with theoretical plate number 5.Supply with above-mentioned reaction solution continuously to this water distilling apparatus.In tower top pressure 66.7kPa, 1 time running of reflux ratio, contain the mixture of first alcohol and water as liquid of top of the tower from the cat head extraction.And liquid at the bottom of the tower is supplied with same water distilling apparatus once again, carry out the 2nd distillation, liquid (liquid at the bottom of the 2nd tower) at the bottom of extraction liquid of top of the tower (the 2nd liquid of top of the tower) and the tower.This moment, tower top pressure was that 13.3kPa, reflux ratio are 1.

Analyze liquid at the bottom of the 2nd liquid of top of the tower and the 2nd tower respectively with gas chromatograph and liquid chromatograph.The methyl glycolate purity of the 2nd liquid of top of the tower is 93 quality %.And in the methyl glycolate of supplying with for the 1st time, what be contained in the 2nd liquid of top of the tower is 53%, and what be contained in liquid at the bottom of the 2nd tower is 22%, and the loss component is 25%.Compare with the by product of the reaction solution that is contained in supply, the contained by product of liquid has increased by 3 moles of % oxyacetic acids, 5 moles of % oxyacetic acid 2-hydroxyl ethyl esters, 2 moles of % ethylene glycol bisthioglycolate ethanol esters (ethylene glycol diglycolate), 1 mole of % methyl glycolate dimer with respect to the methyl glycolate of supplying with at the bottom of the 2nd tower.Fluid viscosity becomes very high at the bottom of the tower of the 2nd distillation tower.Its reason it is believed that it is the generation of the NF molecular weight oligomers of above-mentioned analysis.

Embodiment 3-1

Use reference example 1 gained Au/TiO ₂-SiO ₂The catalyzer synthesizing methyl glycolate.In having the 500mL autoclave of gyratory shaker and condenser, add the catalyzer 18.0g of ethylene glycol 24.1g, methyl alcohol 124.1g, oxyacetic acid 1.1g and reference example, helium is forced into 0.7MPa.With interior temperature rise to 120 ℃, pressure transfers to 1MPa then.Pressure keeps 1MPa, the mixed gas of oxygen 8 volume %, nitrogen 92 volume % is blown in the liquid with the flow that per minute 1 standard rises, 120 ℃ of reactions 4 hours down.

After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph and liquid chromatograph analytical reaction liquid.Contain methyl glycolate 23.5g in the reaction solution, ethylene glycol 2-hydroxyl ethyl ester 1.2g, ethylene glycol 2.0g, oxyacetic acid 1.2g.Therefore the ethylene glycol transformation efficiency is 92 moles of %, and the methyl glycolate yield of ethylene glycol benchmark is 67 moles of %.

Embodiment 3-2

Except from the raw material of embodiment 3-1, removing the oxyacetic acid, carry out same reaction.After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph and liquid chromatograph analytical reaction liquid.Contain methyl glycolate 22.2g in the reaction solution, ethylene glycol 2-hydroxyl ethyl ester 1.4g, ethylene glycol 1.8g, oxyacetic acid 0.9g.Therefore the transformation efficiency of ethylene glycol is 92 moles of %, and the methyl glycolate yield of ethylene glycol benchmark is 63 moles of %.

Embodiment 4-1

After the base product liquid after methyl glycolate in having analyzed embodiment 1-1 is refining, the result contains methyl alcohol 0.3 quality %, water 0.2 quality %, methyl glycolate 5.8 quality %, ethylene glycol 2.0 quality %, oxyacetic acid 1.6 quality %, ethylene glycol-2-hydroxyl ethyl ester 14.8 quality %.Liquid is thick liquid at the bottom of the tower, and the composition outside above-mentioned comprises methyl glycolate oligopolymer, oxyacetic acid-2-hydroxyl ethyl ester oligopolymer.

The catalyzer 18.0g that in having the 500mL autoclave of rotation mixer and condenser, adds ethylene glycol 24.1g, methyl alcohol 124.1g, reference example 1, liquid 10.0g at the bottom of the tower of above-mentioned distillation tower (containing methyl glycolate 0.58g, oxyacetic acid-2-hydroxyl ethyl ester 1.48g, ethylene glycol 0.2g, oxyacetic acid 0.16g) is forced into 0.7MPa with nitrogen.With interior temperature rise to 120 ℃, pressure transfers to 1MPa then.Pressure keeps 1MPa, the mixed gas of oxygen 8 volume %, the nitrogen 92 volume % flow with per minute 1NL is blown in the liquid, 120 ℃ of reactions 4 hours down.

After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph and liquid chromatograph analytical reaction liquid.Contain methyl glycolate 27.1g, oxyacetic acid 2-hydroxyl ethyl ester 2.3g in the reaction solution, ethylene glycol 2.3g, oxyacetic acid 0.9g.

Embodiment 4-2

Adding remove above-mentioned base product liquid among the embodiment 4-1 former expects and reacts equally in the autoclave.

After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph and liquid chromatograph analytical reaction liquid.Contain methyl glycolate 22.2g, oxyacetic acid 2-hydroxyl ethyl ester 1.4g in the reaction solution, ethylene glycol 1.8g, oxyacetic acid 0.9g.

Embodiment 4-3

In autoclave, add base product liquid 10.0g, methyl alcohol 100.5g and storng-acid cation exchange resin (Dow Chemical Company's system, the trade(brand)name Dowex 50W-X8) 0.5g of embodiment 1-1, heated 3 hours down in 100 ℃ while stirring.After the cooling, remove by filter Zeo-karb, analyze the gained reaction solution with gas chromatograph and liquid chromatograph.Contain methyl glycolate 6.0g, oxyacetic acid 2-hydroxyl ethyl ester 1.2g in the reaction solution, ethylene glycol 0.35g, oxyacetic acid 0.02g.

Catalyzer 18.0g at above-mentioned reaction solution adding ethylene glycol 23.5g, methyl alcohol 28.2g, reference example 1 carries out the reaction same with embodiment 4-1.After reaction finishes, cooling, extract reaction solution out, remove by filter catalyzer after, with gas chromatograph, liquid chromatograph and Ka Er-Fischer formula moisture content tester analytical reaction liquid.Contain methyl glycolate 28.5g, oxyacetic acid 2-hydroxyl ethyl ester 2.5g in the reaction solution, ethylene glycol 2.2g, oxyacetic acid 1.0g.

Embodiment 5-1

Refining embodiment 1-1 gained reaction solution.

Supply with above-mentioned reaction solution continuously to following the 20th block of column plate of the distillation tower cat head of stage number 30, extract the mixture (A liquid) that contains methyl alcohol and water from cat head respectively, extract the cut (B liquid) that contains methyl glycolate from the 10th block of column plate of cat head, at the bottom of tower, extract the cut (C liquid) that contains ethylene glycol.The setting tower top pressure is that 13.3kPa, reflux ratio are 1.

Analyze above-mentioned A liquid～C liquid respectively with gas chromatograph and liquid chromatograph.The methyl glycolate purity of B liquid is 99 quality %.And be contained in B liquid in the methyl glycolate of supplying be 83%, what be contained in C liquid is 10%, the loss component is 6%.Compare with the contained by product of supplying with of reaction solution, the by product that is contained in C liquid has increased by 1 mole of % of oxyacetic acid, 3 moles of % of oxyacetic acid 2-hydroxyl ethyl ester, 2 moles of % of methyl glycolate dimer with respect to the methyl glycolate of supplying with.

Embodiment 5-2

Two distillation towers of refining use (stage number is 15) of embodiment 1-1 gained reaction solution.

Count 10 blocks of column plates of the mat woven of fine bamboo strips down to distillation tower (the 1st distillation tower) cat head of stage number 15 and supply with above-mentioned reaction solution continuously, extract the mixture (D liquid) that contains the first alcohol and water from cat head out.The setting tower top pressure is that 66.7kPa, reflux ratio are 1.

Then, liquid at the bottom of the tower of the 1st distillation tower is supplied with to downward the 10th column plate of the 2nd distillation tower cat head continuously, extracted out the cut (E liquid) that contains methyl glycolate from cat head.Setting the 2nd distillation tower tower top pressure is that 13.3kPa, reflux ratio are 1.

Analyze above-mentioned D liquid and E liquid respectively with gas chromatograph and liquid chromatograph.The methyl glycolate purity of E liquid is 92 quality %.And be contained in E liquid in the methyl glycolate of supplying be 59%, what be contained in liquid at the bottom of the 2nd distillation Tata is 9%, the loss component is 32%.Compare with the contained by product of supplying with of reaction solution, be contained in that the by product of liquid has increased by 3 moles of % oxyacetic acids, 5 moles of % oxyacetic acid 2-hydroxyl ethyl esters, 8 moles of % methyl glycolate dimers with respect to the methyl glycolate of supplying with at the bottom of the tower of the 2nd distillation tower.Fluid viscosity becomes very high at the bottom of the 2nd distillation Tata.Its reason it is believed that it is due to the generation of the NF polymer oligopolymer of above-mentioned analysis.

Embodiment 6

React according to continous way shown in Figure 1.Reactor is connecting the stirring tank reactor of dress 500L solution in 2, and distillation tower uses the distillation tower of internal diameter 250mm, column plate sum 30.Catalyzer uses the concoction of the method for reference example 1, and every block response device adds 16kg, is used for suspension bed.120 ℃ of temperature of reaction, the residence time of every block response device is 7 hours.Raw material supplying amount under the stable state comprises that the unreacting material of being supplied with is methyl alcohol 27kg/hr, ethylene glycol 10kg/hr, water 0.5kg/hr, oxyacetic acid-2-hydroxyl ethyl ester 2.4kg/hr and methyl glycolate oligopolymer 4.4kg/hr, and the water in the raw material is 0.7 quality %.From the resultant of reaction that the 2nd block response device is extracted out, contain methyl glycolate 19 quality %.This resultant of reaction is supplied to plays the distillation of the 20th block of column plate on the distillation tower.

The methyl glycolate of extracting out by side stream from the 15th block of column plate of distillation tower is 8.3kg/hr, and the water of extracting out by side stream from the 10th block of column plate is 5.2kg/hr.

The methyl alcohol that obtains from cat head is supplied to the 1st block response device.Liquid at the bottom of the tower that obtains at the bottom of the tower, on one side part clean, supply with the 1st block response device on one side.The ratio of distilling the water of removing from resultant of reaction is 98%.And the water content in the mixture of supplying with that contains methyl alcohol and ethylene glycol is 1.5 quality %.

Physical property measurement method among following embodiment 7-1 and the embodiment 7-2 is as described below.

(1) fusing point

Using Seiko corporate system DSC2000 (differential scanning calorimeter), sample 10mg is added flat aluminum pot, since 20 ℃, be warming up to 300 ℃ with the speed of 10 ℃/min, is fusing point with the endothermic peak temperature.

(2) weight-average molecular weight

Use eastern Cao to make gel permeation chromatograph (GPC).Eluant uses hexafluoroisopropanol, and the spectrum post uses SHODEX system HFIP-LG+HFIP-806M * 2.Use the known polymethylmethacrylate of molecular weight to make calibration curve.

Embodiment 7-1

Use the Au/TiO of reference example 1 gained ₂-SiO ₂Catalyzer carries out the synthetic of oxyacetic acid 2-hydroxyl ethyl ester.In having the 500mL autoclave of rotation mixer and condenser, add the catalyzer 8.14g of ethylene glycol 246.3g and reference example, be forced into 0.7MPa with nitrogen.With interior temperature rise to 110 ℃, pressure transfers to 2MPa then.Pressure keeps 2MPa, and air is blown in the liquid, reacts 9 hours down at 110 ℃.Regulate the air feed speed, making the oxygen concn in the withdrawing gas of condensator outlet is below the 5 volume %.

After reaction finished, cooling, extraction reaction solution were behind the filtering catalyst, with gas chromatograph and liquid chromatograph analytical reaction liquid.Contain oxyacetic acid 2-hydroxyl ethyl ester 66.0g in the reaction solution, oxyacetic acid 7.5g, ethylene glycol 166.1g.Therefore, the ethylene glycol transformation efficiency is 32.5 moles of %, and the oxyacetic acid 2-hydroxyl ethyl ester yield of ethylene glycol benchmark is 27.7 moles of %.

Use the glass Ao Erdexiu distillation tower of stage number 20 then, under reduced pressure, carry out the distillation of above-mentioned reaction solution with intermittent type.At the bottom of above-mentioned reaction solution added tower, heat up in a steamer contained low boiling point component water, ethylene glycol the dereaction liquid, obtain containing liquid at the bottom of the tower of spissated oxyacetic acid 2-hydroxyl ethyl ester from cat head.Contain oxyacetic acid 2-hydroxyl ethyl ester 91.5 quality % at the bottom of the tower in the liquid, oxyacetic acid 3.2 quality %, ethylene glycol 4.2 quality %.

Liquid 150g at the bottom of the above-mentioned tower is added the separable flask of 300ml that possesses stirring rake and distillate pipeline, add catalyzer tin chloride (IV) 5 hydrate 0.11g and carry out the synthetic of condenses.Utilize oil bath to be warming up to 200 ℃, heat up in a steamer by product ethylene glycol.Along with reaction is carried out, slowly reduce pressure, and nitrogen is imported in the reactor, to promote that ethylene glycol heats up in a steamer.The reaction beginning finishes reaction after 15 hours.Obtain brown solid after the cooling.

Gained solid fusing point is 182 ℃, and weight-average molecular weight is 10800.

Embodiment 7-2

In the distillation of embodiment 7-1, heat up in a steamer low boiling point component water, ethylene glycol by cat head after, continue distillation, obtain containing the cut of oxyacetic acid 2-hydroxyl ethyl ester from cat head.Obtain the cut of 133～134 ℃ of tower top pressure 347Pa, tower top temperature.Analyze this cut with gas chromatograph and Ka Er-Fischer formula moisture content tester, the result contains oxyacetic acid 2-hydroxyl ethyl ester 95.1 quality %, ethylene glycol 4.4 quality %, water 0.4 quality %.

Above-mentioned cut 150g is added the separable flask of 300ml that has stirring rake and distillate pipeline, add catalyzer Dibutyltin oxide 78mg, carry out the synthetic of condenses.Utilize oil bath to be warming up to 180 ℃, heat up in a steamer by product ethylene glycol.Along with reaction is carried out, slowly reduce pressure.The reaction beginning finishes reaction after 13 hours.This time pressure be 667Pa.Obtain filbert solid after the cooling.After analyzing the gained solid, the result is 178 ℃ of fusing points, and weight-average molecular weight is 6700.

And, confirm to have following absorption according to FT-IR spectrum shown in Figure 2.1100cm ^-1Near: the C-O stretching vibration of alcohol hydroxyl group, 1200cm ^-1Near: the C-O stretching vibration of ester group, 1420cm ^-1Near: O-H flexural vibration, 1740cm ^-1Near: ester C=O stretching vibration, 3300cm ^-1Near: the O-H stretching vibration.

And according to shown in Figure 3 ¹H-NMR spectrum is observed following chemical shift.4～4.4ppm: be incorporated into the methylene radical of terminal hydroxyl, 4.7～4.9ppm: the methylene radical of the oxyacetic acid of condensation, 5.2～5.6ppm: terminal hydroxyl.

Utilizability on the industry

Alpha-hydroxycarboxylic ester manufacture method of the present invention is compared with the manufacture method of prior art, suppresses Or prevented side reaction, so manufacturing purpose product alpha-hydroxycarboxylic ester more efficiently.

And the gained alpha-hydroxycarboxylic ester can be used as former such as various synthetic resin such as polyglycolic acids Material, also applicable is boilercompound, etchant etc.

Alpha-hydroxy carboxylic acid compounds class condensation product of the present invention can effectively be used as various synthetic resin on upper industry Raw material.

Claims (18)

1. the manufacture method of alpha-hydroxycarboxylic ester is characterized in that, comprises following operation 1～3:

(1) in the presence of oxygen, make (i) 1, between the 2-glycol or (ii) 1,2-glycol and alcohol reaction obtain containing the operation 1 of the resultant of reaction of alpha-hydroxycarboxylic ester;

(2) under reduced pressure, to the distillation of operation 1 gained resultant of reaction, the operation 2 of separating alpha-hydroxycarboxylic ester; With

(3) from operation 1 gained resultant of reaction, remove part or all of water, to operation 1 supply with contain unreacted 1, the operation 3 of the mixture of 2-glycol and/or alcohol.

2. manufacture method according to claim 1 is characterized in that, the distillation in the operation 2 is carried out under the condition of 30～250 ℃ of pressure 13～80000Pa and column bottom temperatures.

3. manufacture method according to claim 1 is characterized in that in operation 3, described mixture contains the water of 0～20 quality %.

4. manufacture method according to claim 1 is characterized in that when operation 1～3 was in stable state, the reaction raw materials in the operation 1 contained the water of 0.1～15 quality %.

5. manufacture method according to claim 1 is characterized in that, in operation 3, removes more than the 30 quality % that anhydrate from resultant of reaction.

6. manufacture method according to claim 1 is characterized in that, in operation 2, when implementing distillation, operation 1 gained resultant of reaction is made film like, contacts with hot face, and resultant of reaction is heated.

7. manufacture method according to claim 1 is characterized in that, the reaction in the operation 1, be the particulate that precious metal forms be supported at supported catalyst in the presence of carry out.

8. manufacture method according to claim 1 is characterized in that, in operation 1, adds alpha-hydroxy carboxylic acid compounds again and/or the alpha-hydroxy carboxylic acid compounds ester oligomer reacts.

9. manufacture method according to claim 1, it is characterized in that liquid is supplied to operation 1 and/or operation 2 at the bottom of the distillation Tata that comprises at least a kind of byproduct of reaction that is selected from alpha-hydroxy carboxylic acid compounds and alpha-hydroxy carboxylic acid compounds ester oligomer that will generate in operation 1 and/or operation 2.

10. manufacture method according to claim 1 is characterized in that, in operation 1, makes 1,2-two pure and mild alcohol reactions.

11. as manufacture method as described in the claim 10, it is characterized in that, in operation 1, also add at least a kind of being selected from alpha-hydroxy carboxylic acid compounds, alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate, alpha-hydroxy carboxylic acid compounds ester oligomer and react.

12. as manufacture method as described in the claim 10, it is characterized in that, the reaction in the operation 1, be the particulate that precious metal forms be supported at supported catalyst in the presence of carry out.

13. as manufacture method as described in the claim 10, it is characterized in that, in operation 2, reclaim the cut that contains alpha-hydroxycarboxylic ester in the side stream mode.

14. as manufacture method as described in the claim 10, it is characterized in that, with liquid at the bottom of the distillation Tata that contains at least a kind the byproduct of reaction that is selected from alpha-hydroxy carboxylic acid compounds, alpha-hydroxy carboxylic acid compounds-2-hydroxyalkyl acrylate, alpha-hydroxy carboxylic acid compounds ester oligomer that generates in operation 1 and/or the operation 2, be supplied to operation 1 and/or operation 2.

15. as manufacture method as described in the claim 10, it is characterized in that, with liquid at the bottom of the tower that contains the alpha-hydroxy carboxylic acid compounds ester oligomer that generates in operation 1 and/or the operation 2 with corresponding to the ester group-C in the oligopolymer (=after O) the pure R-OH of OR (but R is organic residue) contacts, be supplied to operation 1 and/or operation 2.

16., it is characterized in that described 1, the 2-glycol is an ethylene glycol as manufacture method as described in the claim 10, described alpha-hydroxycarboxylic ester is an ethyl glycolate.

17. as following (I)～(III) alpha-hydroxy carboxylic acid compounds class condenses as described in each, wherein,

(I) for containing the alpha-hydroxy carboxylic acid compounds class condensation part shown in the following general formula (2) with shown in the following general formula (3) 1, the alpha-hydroxy carboxylic acid compounds class condenses of 2-glycol chains, its two ends are the alpha-hydroxy carboxylic acid compounds class condenses shown in following general formula (4) or the following general formula (5),

In general formula (2),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (3),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (4),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (5),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

(II) be the alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (6),

In general formula (6), R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group, and the scope of n is 1～200;

(III) be the alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (7),

In general formula (7), R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group, and n1, n2 are all more than 1, and the scope of n1+n2 is 2～200.

18. as following (I)～(III) each described alpha-hydroxy carboxylic acid compounds class condenses, it is by in the presence of catalyzer, utilization makes shown in the following general formula (1) 1, the manufacture method of the alpha-hydroxycarboxylic ester of 2-glycol interreaction obtains the alpha-hydroxy carboxylic acid compounds hydroxyalkyl acrylate, utilize again and take off 1, the reaction of 2-glycol obtains the hydroxyalkyl ester condensation of gained alpha-hydroxy carboxylic acid compounds, wherein

In general formula (1),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

(I) for containing the alpha-hydroxy carboxylic acid compounds class condensation part shown in the following general formula (2) with shown in the following general formula (3) 1, the alpha-hydroxy carboxylic acid compounds class condenses of 2-glycol chains, its two ends are the alpha-hydroxy carboxylic acid compounds class condenses shown in following general formula (4) or the following general formula (5),

In general formula (2),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (3),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (4),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

In general formula (5),

R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group;

(II) be the alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (6),

In general formula (6), R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group, and the scope of n is 1～200;

(III) be the alpha-hydroxy carboxylic acid compounds class condenses shown in the following general formula (7),

In general formula (7), R represents the alkyl of hydrogen or carbonatoms 1～5, and described alkyl can have substituting group, and n1, n2 are all more than 1, and the scope of n1+n2 is 2～200.

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