JPH09268156A - Production of alpha-hydroxycarboxylic acid ester and catalyst used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce an α-hydroxycarboxylic acid ester at a low cost and obtain a catalyst capable of efficiently producing the α- hydroxycarboxylic acid ester at the low cost. SOLUTION: A 1,2-diol is oxidized in the vapor phase in a reactor 7 at the former stage and the produced gaseous α-oxoaldehyde, together with an alcohol gasified in a gasifying chamber 14, is then introduced into a reactor 11 at the latter stage and reacted in the presence of a catalyst in the reactor 11 at the latter stage to thereby produce an α-hydroxycarboxylic acid ester. Thereby, the α-hydroxycarboxylic acid ester is produced in a substantially one stage by using the inexpensive 1,2-diol as a raw material. The catalyst comprises a solid acid catalyst.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to α
-A method for producing a hydroxycarboxylic acid ester and a catalyst used therefor.

Α-Hydroxycarboxylic acid esters are industrially useful compounds. For example, glycolic acid esters having the simplest structure are used as cleaning agents for boilers, additives for plating, etching agents, tanning agents, etc. Can be used. Glycolic acid obtained by hydrolyzing an α-hydroxycarboxylic acid ester can also be used for the same purpose as the glycolic acid ester.

Further, glyoxylic acid esters obtained by oxidizing glycolic acid esters are industrially useful compounds. For example, glyoxylic acid obtained by hydrolyzing the glyoxylic acid ester is a very useful compound as an intermediate raw material for various products such as pharmaceuticals, cosmetics, fragrances and agricultural chemicals. Further, polyacetal carboxy sodium salt obtained from a polymer of glyoxylic acid ester,
It is useful as a builder for detergents.

[0004]

2. Description of the Related Art Conventionally, various synthetic methods shown below have been proposed as a method for producing an .alpha.-hydroxycarboxylic acid ester. (1) A method of esterifying α-hydroxycarboxylic acid. (2) Method to esterify the obtained polyglycolide after carbonylation of formaldehyde (Japanese Patent Publication No. 6-678
No. 75 gazette). (3) Method for reducing oxalic acid diester (JP-A-6-263692)
Issue). The methods (2) and (3) are methods for producing glycolic acid ester, which is one of α-hydroxycarboxylic acid esters.

The esterification reaction of the method (1) can be carried out in the same manner as a general esterification reaction. For example, it is carried out using alcohol in the presence of an acid catalyst such as sulfuric acid or an ion exchange resin. . Α- which is a raw material of the method (1)
Hydroxycarboxylic acid can be obtained, for example, by liquid phase oxidation of 1,2-diol using a noble metal catalyst such as platinum. The above liquid-phase oxidation can be carried out under normal pressure when ethylene glycol is used as the 1,2-diol.

For example, in JP-A-60-39063, glycolic acid (α-hydroxycarboxylic acid) can be obtained in a high yield of 88% by carrying out liquid phase oxidation under normal pressure using ethylene glycol as a substrate. ing. Further, the subsequent esterification reaction of glycolic acid also proceeds efficiently,
The glycolic acid ester is obtained in high yield.

In the method (2), the carbonylation reaction of formaldehyde is carried out under high pressure using sulfuric acid as a catalyst and a Group 1B element as a cocatalyst.
The sulfuric acid-containing polyglycolide obtained in the above reaction is esterified with alcohol to obtain the target glycolic acid ester.

In the method (3), the glycolic acid ester is obtained by reducing the oxalic acid diester with hydrogen in the gas phase in the presence of a supported metal catalyst.

[0009]

However, (1)
In the method (1), the reaction process has two steps and is complicated. In addition, the manufacturing apparatus becomes expensive as a whole.

In the method (2), the yields of both the first-stage carbonylation reaction and the second-stage esterification reaction are relatively high in the 80% range, but the total yield is 60%.
Insufficient as a stand. Furthermore, since the reaction is performed under pressure using highly corrosive sulfuric acid, an expensive reactor having pressure resistance and corrosion resistance is required. In addition, the glycolic acid ester obtained by the above esterification reaction contains sulfuric acid used as a catalyst. Therefore, it is necessary to treat the sulfuric acid with a base such as an aqueous solution of sodium hydroxide and then to purify it by distillation. Therefore, the reaction process becomes complicated and the manufacturing apparatus becomes expensive as a whole.

In the method (3), although the selectivity of glycolic acid ester is relatively high in the 70% range, the conversion rate is high.
It is as low as 50%. For this reason, the yield of glycolic acid ester is insufficient in the 40% range. Moreover, the oxalic acid diester used as a raw material is expensive.

As described above, the above-mentioned conventional method has various problems in terms of productivity, economy, etc.
There is a problem that the hydroxycarboxylic acid ester cannot be produced inexpensively and efficiently.

That is, the present invention has been made in view of the above-mentioned conventional problems, and an object thereof is a production method capable of producing an α-hydroxycarboxylic acid ester inexpensively and efficiently, and a catalyst used therefor. To provide.

[0014]

Means for Solving the Problems The inventors of the present invention have made extensive studies on a method for producing an α-hydroxycarboxylic acid ester, and as a result, by reacting α-oxoaldehyde with an alcohol in the presence of a catalyst, the cost can be reduced. It has been found that the α-hydroxycarboxylic acid ester can be produced efficiently. Further, they have found that a solid acid catalyst is particularly suitable as the above-mentioned catalyst, and completed the present invention.

That is, in the method for producing an α-hydroxycarboxylic acid ester according to the first aspect of the present invention, in order to solve the above-mentioned problems, α-oxoaldehyde and alcohol are
It is characterized by reacting in the presence of a catalyst.

In order to solve the above problems, the method for producing an α-hydroxycarboxylic acid ester according to the second aspect of the present invention is the method for producing an α-hydroxycarboxylic acid according to the first aspect, in the presence of oxygen. It is characterized by reacting.

In order to solve the above-mentioned problems, the method for producing an α-hydroxycarboxylic acid ester according to the third aspect of the present invention is the method for producing an α-hydroxycarboxylic acid according to the first or second aspect, wherein Oxoaldehyde
Gaseous α-obtained by vapor-phase oxidation of 1,2-diol
It is characterized by being an oxoaldehyde.

In order to solve the above-mentioned problems, the method for producing an α-hydroxycarboxylic acid ester according to a fourth aspect of the present invention is the production method according to any one of the first to third aspects, wherein the catalyst is It is characterized by being a solid acid catalyst.

The catalyst according to the invention of claim 5 is the catalyst used in the production method according to any one of claims 1 to 3, and is characterized by comprising a solid acid catalyst.

The present invention will be described in detail below. The method for producing an α-hydroxycarboxylic acid ester according to the present invention is a method in which an alcohol is added to α-oxoaldehyde and the reaction is performed in the presence of a catalyst.

The above α-oxoaldehyde is not particularly limited, but α-oxoaldehyde having 2 to 6 carbon atoms such as glyoxal and pyruvylaldehyde is particularly preferably used. As the above-mentioned α-oxoaldehyde, for example, a gaseous α-oxoaldehyde obtained by a method of vapor-phase oxidation of 1,2-diol, a method of heating an α-oxoaldehyde solution, or the like is used. it can.

Of these, it is particularly preferable to use a gaseous α-oxoaldehyde obtained by subjecting 1,2-diol to gas phase oxidation. As a result, the gas generated by the gas phase oxidation of 1,2-diol can be reacted with the alcohol in the gas phase. That is, since different gas phase reactions can be combined, the reaction intermediate can be continuously reacted without taking out the gaseous α-oxoaldehyde from the reaction system. Therefore, 1,2-
The α-hydroxycarboxylic acid can be produced from the diol in substantially one step.

The above-mentioned 1,2-diol may be a compound capable of producing α-oxoaldehyde by an oxidation reaction, but a 1,2-diol having 2 to 6 carbon atoms such as ethylene glycol and propylene glycol is particularly preferable. It is preferably used.

The above-mentioned gas phase oxidation reaction of 1,2-diol (hereinafter referred to as the first-stage reaction) is not particularly limited as long as it is a method capable of obtaining gaseous α-oxoaldehyde.
That is, the first-stage reaction can be carried out according to various known methods for producing α-oxoaldehyde.

Examples of the method for producing α-oxoaldehyde include metal Ag and CuO-ZnO / α-Al ₂ O.
₃ , using Ag ₂ O—SiO ₂ —ZnO or the like as a catalyst
-Methods for the gas phase oxidation of diols are known. Especially,
In the reaction catalyzed by metal Ag in the presence of a small amount of phosphorus-containing component, α-oxoaldehyde was obtained in a high yield (maximum yield of 84%) (JP-A-58-59933, JP-A-58-59933). 3-
(232835 publication).

Specifically, the first-stage reaction may be carried out, for example, by using a fixed bed flow type reactor which is two-stage connected to a reaction device for a second-stage reaction which will be described later. That is, in the first-stage reaction, a commercially available metal Ag having a uniform particle size, for example, is charged as a catalyst in the first-stage reactor (first-stage reactor), and a gaseous 1,2-diol and oxygen are circulated. Just go. Then, the obtained gas may be introduced into a second-stage reactor (second-stage reactor) that performs a second-stage reaction described later. Gaseous 1, which is supplied to the first stage reactor
The 2-diol is, for example, a liquid 1,2-diol in a vaporization chamber connected to the above-mentioned first-stage reactor,
Obtained by heating at 300 ° C.

The composition of the gas used in the first-stage reaction is 1, 2
-Diol: oxygen = 4 to 10: 4 to 10 (vol%, the rest is nitrogen gas, hereinafter referred to as nitrogen balance),
Further, if necessary, water may be contained in a range of 34 vol% or less. When water is added, it may be added to the liquid 1,2-diol before vaporization in the range of 50% by weight or less. Also, if necessary, phosphorus-containing components such as triethyl phosphite and diethyl phosphate are added to the raw material 1,2-diol within the range of 100 ppm (the addition amount of phosphorus to 1,2-diol) or less. You may. Thereby, the production amount of α-oxoaldehyde can be further improved.

The space velocity (SV) of the first-stage reaction is 10,0.
It should be 00 to 1,000,000 hr ^-1 . Furthermore, the reaction temperature of the first-stage reaction is 400 to 70 depending on the composition of the gas to be supplied.
It may be selected in the range of 0 ° C. Under the above reaction conditions, when ethylene glycol is used as a substrate and metal Ag is used as a catalyst in the first-stage reaction, the conversion of 1,2-diol is 80 to 100% and the yield of α-oxoaldehyde is 40-85%.

On the other hand, instead of performing the above-mentioned first-stage reaction, α
When the -oxoaldehyde solution is heated to obtain the gaseous α-oxoaldehyde, for example, a mixed solution obtained by adding alcohol to the α-oxoaldehyde solution may be heated to be gasified. When an aqueous solution is used as the α-oxoaldehyde solution, the presence of a large amount of water reduces the yield of the target α-hydroxycarboxylic acid ester, and therefore the aqueous solution preferably has a high concentration.

As the reaction apparatus used for the reaction of the gaseous α-oxoaldehyde and the alcohol (hereinafter referred to as the latter-stage reaction), a fixed bed flow type reactor may be used.

Examples of alcohols used in the reaction include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, tert-butanol, hexanol, cyclohexanol, octanol, 2-ethyl. Hexanol, lauryl alcohol, stearyl alcohol, and other industrially readily available alkyl alcohols and phenols with 1 to 18 carbon atoms,
Aromatic alcohols such as benzyl alcohol may be mentioned. Of the above examples, preferred are alkyl alcohols having 1 to 4 carbon atoms such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, tert-butanol, and the like. Are methanol and ethanol.

The ratio of the α-oxoaldehyde to the alcohol to be subjected to the second-stage reaction may theoretically be an equimolar amount of alcohol to the α-oxoaldehyde, but by using the alcohol in excess, The yield of α-hydroxycarboxylic acid ester can be further improved.

The latter-stage reaction can be carried out in the presence of oxygen, if necessary. Thereby, the yield of α-hydroxycarboxylic acid ester can be further improved. The ratio of α-oxoaldehyde to oxygen used in the second-stage reaction is not particularly limited. That is, as for the amount of oxygen supplied to the second-stage reaction, when supplying the gas obtained by the first-stage reaction, the unreacted oxygen content in the first-stage reaction is sufficient, and it is usually not necessary to newly supply oxygen. . However, when the oxygen concentration in the gas used for the second-stage reaction is low, the yield of α-hydroxycarboxylic acid ester decreases, so when the amount of unreacted oxygen in the first-stage reaction is small, new oxygen is supplied. Is preferred.

From the above, a particularly preferred gas composition for the second-stage reaction is α-oxoaldehyde: oxygen: alcohol: water = 3-5: 1-8: 5-25: amount produced by the first-stage reaction ( vol%, nitrogen balance) range.
If the amount of alcohol supplied is less than this range, α
-The yield of hydroxycarboxylic acid ester is reduced. On the other hand, even if the supply amount is increased from this range, the yield of α-hydroxycarboxylic acid ester does not improve, and the amount of unreacted alcohol increases. Therefore, the amount of alcohol to be recovered and reused is large, which is not preferable.

The reaction temperature of the second-stage reaction can be arbitrarily selected depending on the catalyst used and the like, but it can be carried out in a wide range of 150 to 500 ° C, preferably 180 to 500 ° C. The space velocity (SV) can also be arbitrarily selected according to the catalyst used and the like, but it can be carried out in a wide range of 500 to 10,000 hr ^-1 , preferably 1,000 to 5,000.
hr ^-1 .

The catalyst for the second-stage reaction is not particularly limited, but a solid acid catalyst is preferably used. Examples of the solid acid catalyst include metal phosphates such as aluminum phosphate, boron phosphate and iron phosphate; alumina (Al
₂ O ₃ ), silica (SiO ₂ ), titania (Ti
O _2), oxides such as zirconia (ZrO _2); Silica -
Composite oxides such as alumina, silica-zirconia, silica-magnesia (MgO), titania-silica, titania-alumina; zeolites such as HY type zeolite and La-Y type zeolite; clay minerals such as kaolin and montmorillonite; heteropoly Acids; metal sulfates; solidified phosphoric acid obtained by supporting phosphoric acid on a carrier such as diatomaceous earth, silica gel, quartz sand, and titanium oxide; solidified sulfuric acid prepared by supporting sulfuric acid on these carriers. To be The ratio of metal to phosphorus in the metal phosphate may deviate from the stoichiometric ratio of orthophosphate. Specifically, metal / phosphorus =
It is in the range of 1 / 0.5 to 1/2, but more preferably close to the stoichiometric ratio of orthophosphate. Only one kind of these solid acid catalysts may be used, or two or more kinds thereof may be appropriately mixed and used.

As the above solid acid catalyst, a commercially available reagent or the like may be used as it is or a prepared one may be used.
For example, when a metal phosphate is prepared, the catalyst precursor may be prepared by using a metal salt and a phosphoric acid source by a coprecipitation method from an aqueous solution, a kneading method in the form of a slurry, or the like. As the above metal salts, metal nitrates and carbonates,
Examples thereof include oxalate, hydroxide and chloride. Examples of the phosphoric acid source include phosphates such as orthophosphoric acid, ammonium phosphate, ammonium monohydrogen phosphate and ammonium dihydrogen phosphate. The combination of the metal salt and the phosphoric acid source is not particularly limited, and various combinations are possible. In addition, when the oxide is prepared, the catalyst precursor may be prepared by a coprecipitation method from an aqueous solution, a kneading method in the form of a slurry, or the like. Furthermore, when preparing HY-type zeolite or La-Y-type zeolite, commercially available products are used as H ⁺ ions or La ⁺
The catalyst precursor may be prepared by ion exchange with ions.

The above catalyst precursor can be used as a catalyst as it is, but it is dried in air at 100 to 120 ° C., calcined in air, and further molded as required, or the particle size is changed. Are preferably aligned. Although the calcination temperature varies depending on the type of solid acid catalyst, it is in the range of 300 to 700 ° C, and more preferably in the range of 400 to 600 ° C.

The above-mentioned heteropolyacid can be used as a catalyst as it is, but it is preferable to support it on a carrier and use it as a so-called supported heteropolyacid. As the carrier in this case, a carrier that does not adversely affect the second-stage reaction and is stable to heteropolyacid is preferable.
Examples thereof include silica, titania, diatomaceous earth, and the like. Also,
The supporting method is not particularly limited, and so-called kneading method, impregnation supporting method, or the like can be adopted. The supported heteropolyacid does not need to be subjected to pretreatment such as drying and firing before being subjected to the second-stage reaction, but it is more preferable to pretreat at a temperature higher than the reaction temperature.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG. In the following description, a case of using a two-stage fixed bed flow type reactor as a reaction device will be described as an example.
The reaction device is not limited to the configuration shown in FIG.

As shown in FIG. 1, the above reactor comprises a raw material tank 1, a vaporization chamber 3, a pre-reactor 7 and a raw material tank 1.
2, the vaporization chamber 14, the post-reactor 11 and the like.

The raw material tank 1 contains 1,2-diol,
If necessary, a liquid raw material (hereinafter referred to as a pre-stage raw material) containing triethyl phosphite, which is a phosphorus source for accelerating the reaction, and / or water is added. The pre-stage raw material in the raw material tank 1 is quantitatively supplied to the vaporization chamber 3 by a pump 2 such as a micro pump.

In the vaporizing chamber 3, the raw material tank 1 to the pump 2
A raw material supply port 4 to which the former stage raw material is supplied through and a gas supply port 5 to which a mixed gas of air and nitrogen is supplied are provided. A sheathed heater is wound around the vaporization chamber 3 so as to heat and vaporize the former raw material.
Then, in order to control the temperature in the vaporization chamber 3, the diameter 1 /
A 16-inch thermocouple protection tube (not shown) is inserted in the vaporization chamber 3, and a thermocouple 6 having a diameter of 0.5 mm is inserted in the protection tube. Further, the outlet of the vaporization chamber 3 is connected to the pre-stage reactor 7, and the vaporized pre-stage raw material is sent to the pre-stage reactor 7 together with the mixed gas.

The front-stage reactor 7 is a SU having a diameter of 1/4 inch.
Quartz wool is inserted as a catalyst support into a reaction tube made of S, and a predetermined amount of metal Ag (for example, manufactured by Yokohama Metal Co., Ltd.) is filled as a catalyst. Then, the catalyst layer 7 for circulating gas by the metal Ag
a is formed. A sheathed heater is wound around the front-stage reactor 7 so that the catalyst layer 7a can be heated. Further, in order to measure the temperature of the catalyst layer 7a and control the temperature, as in the vaporization chamber 3,
A thermocouple protective tube (not shown) having a diameter of 1/16 inch is inserted in the front-stage reactor 7, and the diameter of the protective tube is 0.
A 5 mm thermocouple 8 is inserted. A three-way cock 9 is connected to the gas outlet of the front-stage reactor 7.

The three-way cock 9 mixes the reaction gas containing α-oxoaldehyde sent from the pre-reactor 7 with oxygen or air supplied from the gas supply port 10 and supplies the mixed gas to the vaporization chamber 14. Then, the three-way cock 9 sends out the reaction gas from the gas supply port 10 by switching when analyzing the composition of the reaction gas of the first-stage reaction. The reaction gas is, for example, collected in water under ice temperature in a gas collection bottle (not shown) connected to the gas supply port 10.

The raw material tank 12 contains alcohol. The alcohol in the raw material tank 12 is quantitatively supplied to the vaporization chamber 14 by a pump 13 such as a micro pump.

The vaporizing chamber 14 is supplied with the reaction gas of the pre-stage reaction and oxygen or nitrogen via the three-way cock 9, and the liquid alcohol from the raw material tank 12 via the pump 13. The vaporization chamber 14 is wound around a sheathed heater and heated to a predetermined temperature to vaporize alcohol. The outlet of the vaporization chamber 14 is connected to the post-reactor 11, and the gas sent from the three-way cock 9 and the vaporized alcohol are mixed and sent to the post-reactor 11.

The post-reactor 11 has a U-shaped reaction tube made of SUS and having an inner diameter of 10 mm, and a predetermined amount of a catalyst (hereinafter referred to as a post-catalyst) to be used for the post-reaction. And, the catalyst layer 11a through which gas can flow by the latter-stage catalyst
Are formed. The latter-stage reactor 11 can be heated by the molten salt bath 16.
Further, in order to measure the temperature of the catalyst layer 11a and control the temperature, a thermocouple protective tube (not shown) having a diameter of 1/16 inch is inserted into the latter-stage reactor 11, and the diameter of the protective tube is set in the protective tube. A 0.5 mm thermocouple 15 is inserted. The gas outlet of the second-stage reactor 11 is connected via a three-way cock 17 to a gas collecting device 18 that collects the flowing gas after the second-stage reaction. That is, the reaction gas of the second-stage reaction is collected by the gas collecting device 18. The three-way cock 17 is switched, for example, when the reaction gas is not collected, and exhausts the reaction gas to an exhaust trap (not shown) through the exhaust port 17a.

The gas collecting device 18 is equipped with gas collecting bottles 19 and 19 connected in series, and an ice bath 20 for cooling the gas collecting bottles 19 and 19 with ice. Gas collection bottle 19.1
A solvent capable of absorbing the reaction gas, for example, acetonitrile is contained in 9 and the reaction gas is collected at an ice temperature. Further, the gas outlet 18a of the gas collection device 18 is connected to an exhaust trap (not shown).

Next, an example of a method for producing an α-hydroxycarboxylic acid ester using the reactor having the above-mentioned structure will be described.

First, a gas mixture of air and nitrogen is vaporized in the vaporization chamber 3
Is continuously supplied to the gas supply port 5 of 1, and the liquid front-stage raw material containing 1,2-diol is continuously supplied to the raw material supply port 4 of the vaporization chamber 3 from the raw material tank 1 via the pump 2. . Next, the first-stage raw material is heated at a predetermined temperature in the vaporization chamber 3 to be vaporized and mixed with the above-mentioned mixed gas. Then, the obtained mixed gas is supplied to the pre-reactor 7.

The mixed gas is circulated through the catalyst layer 7a of the pre-reactor 7 heated to a predetermined temperature to carry out the pre-reaction.
Then, the reaction gas is sent to the three-way cock 9.

Next, oxygen or air is introduced from the gas supply port 10 of the three-way cock 9, mixed with the reaction gas of the preceding reaction and supplied to the vaporization chamber 14. Liquid alcohol is supplied to the vaporization chamber 14 from the raw material tank 12 connected via the pump 13, and the alcohol is vaporized by heating,
It is sent to the post-reactor 11 together with the flow gas and oxygen after the pre-step reaction sent from the three-way cock 9.

Then, the mixed gas supplied from the vaporization chamber 14 is heated to a predetermined temperature, and the catalyst layer 1 of the post-reactor 11 is heated.
It is circulated in 1a to carry out a second-stage reaction. Then, the reaction gas is sent to the gas collection device 18 through the three-way cock 17,
Collect using acetonitrile or the like under ice temperature. Thereby, an α-hydroxycarboxylic acid ester is obtained.

Further, instead of performing the first-stage reaction, when performing the second-stage reaction using a gaseous α-oxoaldehyde obtained by heating an α-oxoaldehyde solution, the vaporization chamber 1
Connect the gas supply line to 4 and oxygen or air,
In addition to supplying a mixed gas containing nitrogen, the raw material tank 1
It suffices to mix the alcohol and the α-oxoaldehyde solution into 2 and charge them. In this case, each device for carrying out the first-stage reaction can be omitted.

[0056]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The conversion, selectivity and yield shown in the following examples were performed according to the following calculation method. The reaction gas of the first-stage reaction was collected with water at ice temperature and then analyzed by high performance liquid chromatography equipped with a differential refractometer detector. Then, high-performance liquid chromatography was used to quantify the unreacted 1,2-diol (hereinafter simply referred to as diol) and the produced α-oxoaldehyde (hereinafter simply referred to as oxoaldehyde). The reaction gas of the second-stage reaction was collected by acetonitrile under ice temperature, and then analyzed by high performance liquid chromatography equipped with a differential refractometer detector and gas chromatography equipped with an FID detector. Then, the unreacted oxoaldehyde was quantified by high performance liquid chromatography, and the target α-hydroxycarboxylic acid ester (hereinafter referred to as hydroxy ester) was quantified by gas chromatography.

Reacted diol (mol) = supplied diol (mol) -unreacted diol (mol) diol conversion (%) = (reacted diol (mol) / supplied diol (mol)) x 100 oxoaldehyde Yield (%) = (oxoaldehyde (mol) generated in the first stage / diol (mol) supplied) × 100 reacted oxoaldehyde (mol) = oxoaldehyde (mol) generated in the first stage−unreacted oxoaldehyde (mol) mol) Oxoaldehyde conversion (%) = (Reacted oxoaldehyde (mol) / Oxoaldehyde produced in the previous stage (mo)
l)) × 100 hydroxyester selectivity (%) = (hydroxy ester produced (mol) / hydroxy ester reacted (mol))
× 100 Hydroxyester yield (%) based on diol =
(Hydroxyester produced (mol) / diol supplied (mol)) × 100 space velocity (SV) (hr ⁻¹ ) = (gas supply amount per hour (ml) / catalyst amount (ml)) The speed is a value converted into the standard state (NTP).

Example 1 In this example, a gaseous glyoxal obtained by vapor-phase oxidation of ethylene glycol (diol) was used as the oxoaldehyde.

The pre-reaction for obtaining gaseous glyoxal by oxidative dehydrogenation of ethylene glycol was carried out under the following conditions using the above-mentioned reaction apparatus. That is, the vaporization chamber 3
Was heated to 180 ° C. in advance and maintained at this temperature before feeding the former raw material. In the first-stage raw material, the amount of triethyl phosphite added to ethylene glycol was such that the phosphorus concentration relative to ethylene glycol was 60 ppm.

The composition of the mixed gas supplied from the vaporization chamber 3 to the pre-stage reactor 7, that is, the gas supplied to the pre-stage reactor 7 is
Ethylene glycol was 6 vol% and oxygen was 7 vol% (nitrogen balance). As the catalyst for the first-stage reaction (hereinafter referred to as the first-stage catalyst), 0.8 g of metal Ag (manufactured by Yokohama Metal Co., Ltd.) having a particle size of 20 to 30 mesh was used.
The reaction conditions for the first-stage reaction were a reaction temperature of 440 ° C. and a space velocity (SV) of 830,000 hr ⁻¹ .

The first stage reaction was carried out under the above reaction conditions, and the reaction gas was analyzed by the above method. As a result, the conversion rate of ethylene glycol is 98% and the yield of glyoxal is 82%.
Met.

The second-stage reaction for obtaining a glycolic acid ester (hydroxy ester) was carried out under the following conditions using the above-mentioned reactor. That is, methanol was used as alcohol, and the composition of the gas supplied from the vaporization chamber 14 to the post-stage reactor 11 was 4 g as shown in Table 1.
ol%, oxygen 5 vol%, methanol 20 vol% (nitrogen balance). In addition, oxygen is the gas supply port 1
From 0, only the deficiency was supplied as pure oxygen.

As the latter-stage catalyst, aluminum phosphate prepared by the coprecipitation method as described below was used. That is, first,
Predetermined amount of aluminum (III) nitrate nonahydrate (Al (NO
_{3) 3} · 9H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in water, it was added 85% phosphoric acid aqueous solution having a predetermined amount therein. 28% aqueous ammonia was added dropwise to this solution to form a precipitate.
The dropping was completed when the pH of the solution reached 7. The precipitate was concentrated to a slurry using a hot water bath. The obtained slurry was dried in air at 120 ° C. and then calcined in air at 500 ° C. for 3 hours. After firing, the particle size was adjusted to 9-20 mesh. Then, the latter-stage catalyst was filled in the latter-stage reactor 11. The ratio of phosphorus to aluminum is
1: 1.

The reaction conditions for the second-stage reaction are, as shown in Table 1, a reaction temperature of 240 ° C. and a space velocity (SV) of 3,000 hr ^−1.
And

The second-stage reaction was carried out under the above reaction conditions, and the reaction gas was analyzed by the above method. As a result, as shown in Table 1, the conversion of glyoxal was 100%, the selectivity of methyl glycolate was 91.2%, and the yield of methyl glycolate based on ethylene glycol was 74.8%.

Example 2 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the supply gas for the second-stage reaction, pure oxygen and gaseous methanol were further supplied to the reaction gas obtained in the first-stage reaction to give glyoxal of 4 v as shown in Table 1.
ol%, oxygen 3 vol%, methanol 20 vol% (nitrogen balance).

The second-stage reaction was carried out by charging aluminum phosphate prepared in the same manner as in Example 1 into the second-stage reactor 11 and supplying the mixed gas having the above composition under the reaction conditions shown in Table 1. It carried out similarly to 1. Table 1 shows the obtained results.
It was shown to.

[Example 3] The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the latter-stage catalyst, aluminum phosphate having a phosphorus / aluminum ratio of 1: 1.2 was used. The above-mentioned aluminum phosphate was prepared in the same manner as in Example 1 except that the amount of the 85% phosphoric acid aqueous solution based on aluminum (III) nitrate nonahydrate was changed.

The second-stage reaction was carried out in the same manner as in Example 1 under the reaction conditions shown in Table 1 by supplying the mixed gas having the same composition as in Example 1 to the latter-stage reactor 11 filled with the above-mentioned second-stage catalyst. . The obtained results are shown in Table 1.

Example 4 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the supply gas for the second-stage reaction, pure oxygen and gaseous methanol were further supplied to the reaction gas obtained in the first-stage reaction, and as shown in Table 1, glyoxal was 4 v
ol%, oxygen 5 vol%, methanol 10 vol% (nitrogen balance).

The second-stage reaction was carried out by charging aluminum phosphate prepared in the same manner as in Example 3 into the second-stage reactor 11 and supplying the mixed gas having the above composition under the reaction conditions shown in Table 1. It carried out similarly to 1. Table 1 shows the obtained results.
It was shown to.

Example 5 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

Boron phosphate prepared as follows was used as the second-stage catalyst. That is, a predetermined amount of boric acid (H ₃
BO ₄ (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in water, and a predetermined amount of 85% phosphoric acid aqueous solution was added to form a precipitate. The precipitate was concentrated to a slurry and dried and calcined in the same manner as in Example 1 to make the particle size uniform. Then, the latter-stage catalyst was filled in the latter-stage reactor 11. The ratio of phosphorus to boron is 0.8: 1.

The second-stage reaction was carried out in the same manner as in Example 1 under the reaction conditions shown in Table 1 by supplying the mixed gas having the same composition as in Example 1 to the latter-stage reactor 11 filled with the above-mentioned second-stage catalyst. . The obtained results are shown in Table 1.

Example 6 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

Ferric phosphate prepared as follows was used as the second-stage catalyst. That is, the reagent ferric phosphate (FePO ₄ .nH ₂ O, manufactured by Katayama Chemical Co., Ltd.) was conditioned with water, put in a SUS vat, dried in air at 120 ° C., and then in air 600 Calcination was carried out for 3 hours. After firing, the particle size was adjusted to 9-20 mesh. The ratio of phosphorus to iron is 1: 1.

The second-stage reaction was carried out in the same manner as in Example 1 under the reaction conditions shown in Table 1 by supplying the mixed gas having the same composition as in Example 1 to the latter-stage reactor 11 filled with the above-mentioned second-stage catalyst. . The obtained results are shown in Table 1.

Example 7 The pre-stage reaction was carried out according to Example 1. Supply gas composition of ethylene glycol 5 vol
%, Oxygen is changed to 8 vol% (nitrogen balance), reaction temperature is 580 ° C, space velocity (SV) is
The reaction was carried out in the same manner as in Example 1 except that the amount was changed to 1,000,000. As a result, the conversion rate of ethylene glycol was 95.
%, The yield of glyoxal was 77%.

As the supply gas for the second-stage reaction, the gas obtained in the first-stage reaction was supplied, pure oxygen was supplied to make up for the deficient oxygen, and further gaseous methanol was supplied so that the composition of the supply gas was , As shown in Table 1, glyoxal 4
Vol%, oxygen 5 vol%, methanol 20 vol% (nitrogen balance).

The second-stage reaction was carried out under the reaction conditions shown in Table 1 by using the second-stage reactor 11 in which the mixed gas having the above composition was supplied and the same ferric phosphate as in Example 6 was charged. I went in the same way. The obtained results are shown in Table 1.

[0084]

[Table 1]

[Example 8] The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

Alumina prepared as follows was used as the second-stage catalyst. That is, commercially available alumina (Al ₂ O
₃ , JGC Chemical Co., Ltd., trade name "N611N")
After firing in air at 500 ° C. for 3 hours, the particle size was made uniform to 9 to 20 mesh.

In the second-stage reaction, a mixed gas was supplied in the same manner as in Example 1 except that methanol was changed to propanol to the second-stage reactor 11 filled with the above-mentioned second-stage catalyst, and Table 2 was used.
The reaction was performed in the same manner as in Example 1 under the reaction conditions shown in. Table 2 shows the obtained results.

Example 9 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the second-stage catalyst, titania prepared as follows was used. That is, the anatase-type titania (TiO ₂ , manufactured by Wako Pure Chemical Industries, Ltd.) as a reagent was conditioned with water, dried and baked in the same manner as in Example 1 to make the particle diameter uniform.

The second-stage reaction was carried out in the same manner as in Example 1 under the reaction conditions shown in Table 2 by supplying the mixed gas having the same composition as in Example 1 to the latter-stage reactor 11 filled with the above-mentioned second-stage catalyst. . Table 2 shows the obtained results.

[Example 10] The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the second-stage catalyst, silica-alumina prepared as follows was used. That is, commercially available silica-alumina (manufactured by JGC Chemical Co., Ltd., trade name "N631L")
After calcination in air at 500 ° C for 3 hours, the particle size was made uniform to 9 to 20 mesh. Incidentally, a commercially available silica using - the composition ratio of alumina _{(SiO 2 / Al 2 O 3} ) is a 81.6 / 12.6.

The second-stage reaction was carried out in the same manner as in Example 1 under the reaction conditions shown in Table 2 by supplying the mixed gas having the same composition as in Example 1 to the latter-stage reactor 11 filled with the above-mentioned second-stage catalyst. . Table 2 shows the obtained results.

[Example 11] The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the supply gas for the second-stage reaction, pure oxygen and gaseous methanol were further supplied to the reaction gas obtained in the first-stage reaction to give 5 g of glyoxal as shown in Table 2.
ol%, oxygen 3 vol%, methanol 10 vol% (nitrogen balance).

In the second-stage reaction, the silica-alumina prepared in the same manner as in Example 10 was filled in the second-stage reactor 11, the mixed gas having the above composition was supplied, and the reaction conditions shown in Table 2 were used. It carried out similarly to 1. Table 2 shows the obtained results.
It was shown to.

[Example 12] The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the second-stage catalyst, silica-alumina prepared as follows was used. That is, commercially available silica-alumina (manufactured by JGC Chemical Co., Ltd., trade name "N631H"
L ") was calcined in air at 500 ° C for 3 hours, and then the particle size was adjusted to 9 to 20 mesh. Incidentally, a commercially available silica using - the composition ratio of alumina _{(SiO 2 / Al 2 O 3} ) is a 66.5 / 25.1.

In the second-stage reaction, mixed gas was supplied to the second-stage reactor 11 filled with the above-mentioned second-stage catalyst in the same manner as in Example 1 except that methanol was changed to ethanol, and under the reaction conditions shown in Table 2, The same procedure as in Example 1 was performed. Table 2 shows the obtained results.

Example 13 The first-stage reaction was carried out under the same conditions as in Example 7. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 7.

In the second-stage reaction, silica-alumina prepared in the same manner as in Example 12 was charged into the second-stage reactor 11 and a mixed gas having the same composition as in Example 7 was supplied under the reaction conditions shown in Table 2. The same procedure as in Example 7 was performed. Table 2 shows the obtained results.

Example 14 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the second-stage catalyst, titania-alumina prepared by the coprecipitation method as described below was used. That is, a predetermined amount of aluminum nitrate (III) nonahydrate (Al (NO _{3) 3} ·
9H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd., is dissolved in water, and a predetermined amount of anatase titania (TiO ₂ ,
Wako Pure Chemical Industries, Ltd.) was added. 28% ammonia water was added dropwise to the obtained aqueous solution to form a precipitate.
The dropping was completed when the pH of the solution reached 7. The obtained precipitate was concentrated using a hot water bath until it became a slurry, and this slurry was dried and calcined in the same manner as in Example 1 to make the particle diameter uniform. The composition ratio of the obtained titania-alumina (TiO ₂ / Al ₂ O ₃ ) was 65.0 / 35.0.

The second-stage reaction was carried out in the same manner as in Example 1 under the reaction conditions shown in Table 2 by supplying the mixed gas having the same composition as in Example 1 to the latter-stage reactor 11 filled with the above-mentioned second-stage catalyst. . Table 2 shows the obtained results.

Example 15 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the supply gas for the second-stage reaction, pure oxygen was not supplied to the reaction gas obtained in the first-stage reaction, and only gaseous methanol was supplied. As shown in Table 2, glyoxal was 4 vol%, Oxygen was 1 vol% and methanol was 20 vol% (nitrogen balance).

In the second-stage reaction, titania-alumina prepared in the same manner as in Example 14 was filled in the second-stage reactor 11, a mixed gas having the same composition as in Example 1 was supplied, and the reaction conditions shown in Table 2 were used. The same procedure as in Example 7 was performed. Table 2 shows the obtained results.

Example 16 The first-stage reaction was carried out under the same conditions as in Example 1. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 1.

As the second-stage catalyst, silica-supported 12-tungstophosphoric acid prepared as follows was used. As the catalyst carrier, silica in which spherical silica (trade name "Carriert Q-50" manufactured by Fuji Silysia Chemical Ltd.) was prepared in 9 to 20 mesh was used. A predetermined amount of this silica is added to a predetermined amount of 12-tungstophosphoric acid (H ₃ PW ₁₂ O ₄₀ .nH ₂
O, manufactured by Nippon Inorganic Chemical Industry Co., Ltd.), concentrated in a hot water bath and supported, and then in air at 120 ° C.
And dried. The loading rate of 12-tungstophosphoric acid was 35% by weight in terms of anhydride.

The second-stage reaction was carried out in the same manner as in Example 1 under the reaction conditions shown in Table 2 by supplying the mixed gas having the same composition as in Example 1 to the latter-stage reactor 11 filled with the above-mentioned second-stage catalyst. . Table 2 shows the obtained results.

[0111]

[Table 2]

Example 17 In this example, a gaseous pyruvyl aldehyde obtained by vapor-phase oxidizing propylene glycol (diol) was used as the oxoaldehyde.

The pre-stage reaction for obtaining gaseous pyruvyl aldehyde by oxidative dehydrogenation of propylene glycol was carried out according to Example 1 under the following conditions using the above-mentioned reaction apparatus. That is, in the vaporization chamber 3, before supplying the former raw material,
It was preheated to 180 ° C. and kept at this temperature. In the first-stage raw material, the amount of triethyl phosphite added to propylene glycol was such that the concentration of phosphorus to propylene glycol was 70 ppm.

The composition of the mixed gas supplied from the vaporization chamber 3 to the pre-stage reactor 7, that is, the gas supplied to the pre-stage reactor 7 is
Propylene glycol was adjusted to 4 vol% and oxygen was adjusted to 7 vol% (nitrogen balance). As the catalyst for the first-stage reaction (hereinafter referred to as the first-stage catalyst), 0.8 g of metal Ag (manufactured by Yokohama Metal Co., Ltd.) having a particle size of 20 to 30 mesh was used. The reaction conditions for the first-stage reaction were a reaction temperature of 530 ° C. and a space velocity (SV) of 830,000 hr ⁻¹ .

The first stage reaction was carried out under the above reaction conditions, and the reaction gas was analyzed by the above method. As a result, the conversion rate of propylene glycol was 100% and the yield of pyruvyl aldehyde was 81%.

The second-stage reaction for obtaining a lactic acid ester (hydroxy ester) was carried out under the following conditions using the above-mentioned reactor. That is, as shown in Table 3, the composition of the gas supplied from the vaporization chamber 14 to the post-stage reactor 11 was 3 vol.
%, Oxygen was 7 vol%, and methanol was 18 vol% (nitrogen balance). In addition, oxygen is supplied to the gas supply port 10.
Therefore, only the shortage was supplied as pure oxygen.

Then, using the aluminum phosphate prepared in the same manner as in Example 1 as the second-stage catalyst to be charged in the second-stage reactor 11, the second-stage reaction was carried out under the reaction conditions shown in Table 3. Table 3 shows the obtained results.

Example 18 The first-stage reaction was carried out under the same conditions as in Example 17. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 17.

The feed gas for the second-stage reaction was such that pure oxygen was not supplied to the reaction gas obtained in the first-stage reaction, but only gaseous methanol was supplied. %, Oxygen 7 vol%, methanol 10 vol%
(Nitrogen balance).

In the second-stage reaction, the mixed gas supplied to the second-stage reactor 11 was changed to the above composition, and the reaction temperature was adjusted to 270
Example 17 was repeated except that the temperature was changed from ℃ to 280 ℃. Table 3 shows the reaction conditions of the second-stage reaction and the obtained results.

Example 19 The first-stage reaction was carried out under the same conditions as in Example 17. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 17.

In the second-stage reaction, mixed gas was supplied to the second-stage reactor 11 filled with alumina prepared in the same manner as in Example 8 in the same manner as in Example 17 except that methanol was changed to propanol. Under the reaction conditions shown, Example 1
7 was performed. Table 3 shows the obtained results.

Example 20 The first-stage reaction was carried out under the same conditions as in Example 17. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 17.

In the second-stage reaction, silica-alumina prepared in the same manner as in Example 10 was charged into the second-stage reactor 11, and a mixed gas having the same composition as in Example 17 was supplied under the reaction conditions shown in Table 3. The same procedure as in Example 17 was performed. Table 3 shows the obtained results.

Example 21 The first-stage reaction was carried out under the same conditions as in Example 17. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 17.

As the supply gas for the second-stage reaction, pure oxygen was not supplied to the reaction gas obtained in the first-stage reaction, but only gaseous methanol was supplied. %, Oxygen 3 vol%, methanol 18 vol%
(Nitrogen balance).

In the second-stage reaction, silica-alumina prepared in the same manner as in Example 20 was filled in the second-stage reactor 11, the mixed gas having the above composition was supplied, and the reaction conditions shown in Table 3 were used. The same was done. Table 3 shows the reaction conditions of the second-stage reaction and the obtained results.

Example 22 The first-stage reaction was carried out under the same conditions as in Example 17. Therefore, the composition of the reaction gas in the first-stage reaction is the same as in Example 17.

In the second-stage reaction, the silica-supported 12-tungstophosphoric acid prepared in the same manner as in Example 16 was used in the second-stage reactor 11.
And mixed gas having the same composition as in Example 17 was supplied, and the reaction was carried out in the same manner as in Example 17 under the reaction conditions shown in Table 3. Table 3 shows the obtained results.

[0130]

[Table 3]

As is clear from the results of Examples 1 to 22, the gaseous α-oxoaldehyde obtained by the gas phase oxidation of 1,2-diol is reacted with alcohol in the presence of a catalyst. This shows that the α-hydroxycarboxylic acid ester can be produced with high reaction efficiency (yield).

[0132]

The method for producing an α-hydroxycarboxylic acid ester of the present invention is a method of reacting an α-oxoaldehyde with an alcohol in the presence of a catalyst.

As a result, there is an effect that the α-hydroxycarboxylic acid ester can be produced inexpensively and efficiently.

In the method for producing an α-hydroxycarboxylic acid ester of the present invention, the above α-oxoaldehyde is
Gaseous α-obtained by vapor-phase oxidation of 1,2-diol
The method is oxoaldehyde.

According to the above method, inexpensive 1,2-diol is used as a raw material, and the vapor-phase oxidation of 1,2-diol and the vapor-phase reaction of α-oxoaldehyde and alcohol are continuously carried out. Therefore, the α-hydroxycarboxylic acid ester can be obtained in substantially one step. Thereby, there is an effect that the α-hydroxycarboxylic acid ester can be produced more inexpensively and efficiently.

Further, the catalyst of the present invention is a catalyst used in the above-mentioned production method and has a constitution containing a solid acid catalyst.

As a result, there is an effect that the α-hydroxycarboxylic acid ester can be produced inexpensively and efficiently.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a reactor suitably used in a method for producing an α-hydroxycarboxylic acid ester in an example of the present invention.

[Explanation of symbols]

 7 Pre-reactor 11 Post-reactor 14 Vaporization chamber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B01J 27/16 B01J 27/16 Z 27/18 27/18 Z 27/185 27/185 Z 27 / 199 27/199 Z C07C 67/08 C07C 67/08 // C07B 61/00 300 C07B 61/00 300 (72) Inventor Noboru Saito 5-8 Nishimitabicho, Suita City, Osaka Prefecture Nippon Shokubai Co., Ltd.

Claims (5)

[Claims] 1. An α-oxoaldehyde and an alcohol,
A method for producing an α-hydroxycarboxylic acid ester, which comprises reacting in the presence of a catalyst. 2. The method for producing an α-hydroxycarboxylic acid ester according to claim 1, wherein the reaction is carried out in the presence of oxygen. 3. The α-oxo carboxylic acid according to claim 1, wherein the α-oxo aldehyde is a gaseous α-oxo aldehyde obtained by gas phase oxidation of 1,2-diol. Method for producing acid ester. 4. The method for producing an α-hydroxycarboxylic acid ester according to any one of claims 1 to 3, wherein the catalyst is a solid acid catalyst. 5. A catalyst used in the production method according to any one of claims 1 to 3, which comprises a solid acid catalyst.