Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
  • C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
  • C07D307/06—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
  • C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
  • C07D307/06—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms
  • C07D307/08—Preparation of tetrahydrofuran
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
  • C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds

Definitions

• the present invention relates to a method for purifying a tetrahydrofuran compound. More specifically, the present invention relates to a method for converting 2,3-dihydrofuran contained in a raw material tetrahydrofuran compound into a high boiling point compound that can be easily separated by distillation using an acid catalyst. Moreover, it is related with the manufacturing method of the polyether polyol which uses the tetrahydrofuran compound obtained by this method as a raw material.
• THF tetrahydrofuran
• PTMG polytetramethylene ether glycol
• THF cyclic ethers
• a method of producing a cyclic ether by subjecting a dihydroxy compound to a dehydration cyclization reaction is often used.
• PBT polybutylene terephthalate
• 1,4BG 1,4-butanediol
• terephthalic acid terephthalic acid
• a method for purifying THF produced as a by-product is also mentioned.
• the THF obtained by these methods may contain impurities such as 2,3-dihydrofuran (hereinafter sometimes abbreviated as “2,3DHF”) depending on the production method.
• 2,3DHF 2,3-dihydrofuran
• 2,3DHF (boiling point 55 ° C.) is close to the boiling point of THF (boiling point 66 ° C.) and is therefore expensive to separate by ordinary distillation or the like. Equipment and a large amount of heat are required.
• Patent Document 1 a method of hydrogenating with a noble metal catalyst (Patent Document 1), contacting 2,3DHF with 2-hydroxytetrahydrofuran (hereinafter, “ OFT “is sometimes abbreviated as OTF)), followed by a hydrogenation reaction to separate and remove 2,3DHF (Patent Document 2), contact with mineral acid or ion exchange resin, and 2,3DHF is hydroxytetrahydrofuran And a method of converting it into a condensate derived from dihydrofuran and separating and removing it (Patent Document 3).
• OFT 2-hydroxytetrahydrofuran
• Patent Document 1 uses hydrogen and the precious metal catalyst is expensive, it requires a lot of equipment and catalyst maintenance costs for ensuring safety, so that it is an industrially advantageous method. I could't say that.
• Patent Document 2 is effective in the case where the dehydration treatment of THF containing a large amount of water in advance and the removal of 2,3DHF are combined.
• adding water with a large separation load is industrial from the viewpoint of equipment costs such as distillation towers required for dehydration and the amount of heat related to separation. It was not an effective means.
• the hydrogenation step is essential, there is a problem similar to the above.
• the present invention has been made in view of the above circumstances, and an object thereof is to provide an industrially advantageous purification method capable of easily separating and removing 2,3DHF in a tetrahydrofuran compound. Further, it is industrially advantageous that the purification load of the tetrahydrofuran compound can be reduced by converting 2,3DHF in the tetrahydrofuran compound into an irreversible component that does not return to 2,3DHF even if concentrated in the bottom liquid of the distillation column. Is to provide a simple purification method.
• THF produced as a by-product with water when polyester is produced using 1,4-butanediol as one of raw materials can be procured at a low cost, but contains a large amount of 2,3DHF.
• 2,3DHF 2,3DHF
• the present inventors have controlled the water concentration contained in THF as a raw material and the water concentration in the liquid phase in the reactor and brought into contact with the acid catalyst, It has been found that 2,3DHF can be converted into a high boiling point compound that can be easily separated from THF while suppressing OTF generated by the reaction of 2,3DHF and water. Further, it has been found that if a hydroxy group-containing compound is added to THF as a raw material and brought into contact with an acid catalyst, 2,3DHF can be converted into a high boiling point compound that can be easily separated from THF. Furthermore, it has been found that a polyether polyol having particularly excellent hue can be obtained by using THF from which 2,3DHF has been separated and removed by such a method as a raw material. The present invention has been accomplished based on these findings.
• the gist of the present invention resides in the following [1] to [21].
• a raw material tetrahydrofuran compound containing 2,3-dihydrofuran is brought into contact with an acid catalyst to convert 2,3-dihydrofuran into a high-boiling compound, and then the tetrahydrofuran compound and the high-boiling compound are separated by distillation.
• the raw material tetrahydrofuran compound containing 2,3-dihydrofuran is brought into contact with an acid catalyst to convert 2,3-dihydrofuran into a high boiling point compound, and then the tetrahydrofuran compound and the high boiling point compound are separated by distillation.
• a hydroxy group-containing compound is added to a raw material tetrahydrofuran compound containing 2,3-dihydrofuran to convert 2,3-dihydrofuran to a high boiling point compound in the presence of an acid catalyst, A method for producing purified tetrahydrofuran for separating a boiling point compound.
• [5] The method for producing purified tetrahydrofuran according to any one of [1], [3], and [4], wherein the water concentration in the liquid phase in the reactor is 4900 wtppm or less.
• [6] The method for producing purified tetrahydrofuran according to any one of [1] to [5], wherein the molecular weight of the high boiling point compound is 100 or more.
• [7] The method for producing purified tetrahydrofuran according to any one of [1], [2], and [4] to [6], wherein the high boiling point compound is a 2,3-dihydrofuran condensate.
• 2,3DHF in a tetrahydrofuran compound can be effectively removed by a simple method, and a high-purity tetrahydrofuran compound can be efficiently obtained.
• 2,3DHF can be effectively removed from a 2,3DHF-containing tetrahydrofuran compound by-produced when a polyester is produced using 1,4-butanediol as one of the raw materials by a simple method.
• a polyether polyol with less coloring can be produced by using a purified tetrahydrofuran compound as a raw material.
• a tetrahydrofuran compound as a raw material containing 2,3-dihydrofuran (hereinafter sometimes abbreviated as “raw tetrahydrofuran compound”) is brought into contact with an acid catalyst to give 2,3.
• a method for purifying a tetrahydrofuran compound, wherein dihydrofuran is converted to a high boiling point compound and then separated by distillation, and the method is a method for purifying a tetrahydrofuran compound characterized in that the water content in the raw material tetrahydrofuran compound is 4900 wtppm or less. .
• the second invention of the present invention is a method in which a raw material tetrahydrofuran compound containing 2,3-dihydrofuran is brought into contact with an acid catalyst to convert 2,3-dihydrofuran into a high-boiling compound and then separated by distillation.
• a method for purifying a compound which is characterized in that the water content in the liquid phase in the reactor is 4900 wtppm or less.
• a third invention of the present invention is characterized in that a hydroxy group-containing compound is added to a raw material tetrahydrofuran compound, 2,3-dihydrofuran is converted into a high boiling point compound in the presence of an acid catalyst, and then separated by distillation.
• the purification method of the present invention is a method by which a high-quality tetrahydrofuran compound can be efficiently obtained, and is synonymous with a method for producing a tetrahydrofuran compound.
• the tetrahydrofuran compound means tetrahydrofuran and its derivatives.
• the tetrahydrofuran derivative include compounds in which a hydrogen atom of tetrahydrofuran is substituted with an alkyl group such as a methyl group, an ethyl group, or a propyl group. More specific examples include 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran and the like.
• the content of tetrahydrofuran in the raw material tetrahydrofuran compound of the present invention is not particularly limited, but is usually 10% by mass or more, preferably 50% by mass or more, more preferably 80% by mass or more, still more preferably 95% by mass or more, particularly preferably. It is 98 mass% or more.
• the raw material tetrahydrofuran compound is not particularly limited as long as it contains 2,3DHF, and is obtained by a chemical method, obtained by combining a bio method and a chemical method, or by-produced in a chemical production process. Any of these can be used.
• Processes for producing polyester from raw materials such as THF obtained from furfural and 1,4BG for example, processes for producing PBT from 1,4BG and terephthalic acid, processes for producing polybutylene succinate from 1,4BG and succinic acid, etc.
• THF produced as a by-product with water by the dehydration cyclization reaction of 1,4BG are those commonly used and known per se.
• Tetrahydrofuran derivatives are also obtained by known methods. For example, 3-methyltetrahydrofuran is obtained by dehydration cyclization of 2-methyl-1,4-butanediol.
• PBT by-product THF compound Tetrahydrofuran tends to contain a large amount of impurities such as 2,3DHF, and when used as a raw material for producing polyether polyol as it is, there is a problem that the resulting polyether polyol is colored. Therefore, in the present invention, it is particularly preferable to carry out the above purification method using this THF as a raw material, and to use the obtained high-purity THF as a raw material for producing a polyether polyol.
• the 2,3DHF concentration in the raw material THF compound is preferably 5000 wtppm or less, more preferably 3000 wtppm or less, and still more preferably 1000 wtppm or less.
• a minimum is not specifically limited, Preferably it is 10 wtppm or more, More preferably, it is 300 ppm or more, More preferably, it is 500 ppm or more.
• the water concentration in the raw material THF compound is 4900 wtppm or less, preferably 3000 wtppm or less, more preferably 1500 wtppm or less, more preferably 500 wtppm or less. Although a minimum is not specifically limited, It is preferable that it is 10 wtppm or more, More preferably, it is 50 wtppm or more.
• the water concentration in the raw material THF compound is preferably 4900 wtppm or less, more preferably 3000 wtppm or less, further preferably 1500 wtppm or less, and particularly preferably 500 wtppm or less.
• a minimum is not specifically limited, It is preferable that it is 10 wtppm or more, More preferably, it is 50 wtppm or more.
• the water concentration in the raw material THF compound is too high, atmospheric distillation cannot remove only water due to azeotropic restrictions, and it is contained in purified THF, which hinders the polymerization reaction during the production of polyether polyol. .
• the hydrolysis reaction of 2,3DHF becomes more dominant as the water concentration in the raw material tetrahydrofuran compound is higher, a larger amount of OTF is generated in the reactor.
• the lower limit of the water concentration in the raw material tetrahydrofuran compound is not particularly limited, and it may be completely anhydrous, but dehydration to less than 10 wtppm is not industrially preferable in terms of cost and labor.
• the hydroxy group-containing compound when added to the raw material THF compound, the hydroxy group-containing compound may contain water.
• the water concentration in the raw material THF compound after adding the hydroxy group-containing compound is calculated in the same manner as described above.
• the boiling point of 2,3DHF in the raw material THF compound is 55 ° C., which is close to the boiling point of THF (66 ° C.), and it is difficult to separate and remove by distillation. 2,3DHF is easily converted into a high boiling point compound that causes ring-opening polycondensation in the production process of the polyether polyol and deteriorates the hue of the polyether polyol.
• the raw material THF compound containing 2,3DHF is previously contacted with an acid catalyst to convert 2,3DHF into a high-boiling compound that can be easily separated from the tetrahydrofuran compound, and the tetrahydrofuran compound and the high-boiling compound are converted by a simple method such as distillation. It is effective to separate and remove.
• 2,3DHF is converted into a high-boiling compound that can be easily separated from the tetrahydrofuran compound, distillation, etc. It is also effective to separate and remove the tetrahydrofuran compound and the high boiling point compound by this simple method.
• the type of the hydroxy group-containing compound used in the third invention of the present invention is not particularly limited, and examples thereof include alcohol compounds and compounds having two or more hydroxy groups (hereinafter also referred to as diol components).
• the alcohol compound is not particularly limited, and examples thereof include an aliphatic alcohol, an alcohol having an alicyclic structure, and an aromatic compound having a hydroxyl group.
• an alcohol having 2 to 12 carbon atoms such as ethanol, propanol, butanol, butenol, heptanol, hexanol, hexenol, cyclohexanol, heptanol, decanol, dodecanol or an alcohol having an alicyclic structure, phenol And aromatic compounds having a hydroxyl group such as
• aliphatic alcohols having 2 to 12 carbon atoms or alcohols having an alicyclic structure are preferable, and the resulting high-boiling compounds are easily separated from THF by distillation, and have 4 to 4 carbon atoms such as butanol, hexanol, and dodecanol. Twelve aliphatic alcohols are more preferred.
• the diol component is not particularly limited as long as it is a compound having two or more hydroxy groups, but is preferably an aliphatic or alicyclic compound in which two hydroxyl groups are bonded to two different carbons.
• ethylene glycol propanediol, butynediol, butenediol, butanediol, pentynediol, pentenediol, pentanediol, hexynediol, hexenediol, hexanediol, cyclohexanediol, heptinediol, heptenediol C 2-12 aliphatic or alicyclic compounds such as heptanediol, octynediol, octenediol, octanediol, noninediol, nonenediol, nonanedio
• 1,4-butanediol and 2 to 6-mer polyether polyol are more preferable, and 1,4-butanediol and 2 to 6-mer polytetramethylene ether glycol are more preferable.
• hydroxy group-containing compounds may be used alone or in combination of any kind and ratio.
• the addition amount of the hydroxy group-containing compound is preferably 0.2 or more, more preferably 0.3 or more, and still more preferably 0.5, in molar ratio with respect to the amount of 2,3DHF in the raw material THF compound.
• the upper limit is preferably 10 or less, more preferably 5 or less, still more preferably 3 or less, and particularly preferably 2 or less.
• the compound which has different molecular weight is mixed in the hydroxy group containing compound to add, it is good on the basis of the average molecular weight. When this molar ratio is too low, high boiling is difficult to occur and the processing becomes difficult.
• alkoxytetrahydrofuran is generated as a high boiling point compound.
• methanol is added to and added to a THF compound containing 2,3DHF, methoxytetrahydrofuran (boiling point 112 ° C.) is obtained as the resulting high boiling point compound, and when THF is added to and added to the THF compound, ethoxy tetrahydrofuran (boiling point 171 ° C.).
• an acetal compound is considered to be produced as a high boiling point compound.
• 2,3DHF and 1,4 butanediol are reacted in the presence of an acid catalyst, a tetrahydrofuran derivative to which a 1,4 butanediol structure or a condensation polymer structure of 1,4 butanediol is added is used as a high boiling point compound. It is thought that it is obtained.
• OTF is a by-product. OTF can be separated if it is subjected to multistage distillation or an excessive reflux ratio. Particularly, in the distillation with a high recovery rate of the tetrahydrofuran compound, the heat load is high and the OTF is reduced to 2 by being concentrated at the bottom of the distillation column. , 3DHF may be mixed back into the purified tetrahydrofuran compound.
• the OTF concentration in the tetrahydrofuran compound (purified tetrahydrofuran compound) after purification of the raw material tetrahydrofuran compound containing 2,3DHF by the method of the present invention is preferably 800 wtppm or less, more preferably 100 wtppm or less, and still more preferably Is 50 wtppm or less, particularly preferably 20 wtppm or less.
• the 2,3DHF concentration in the tetrahydrofuran compound (purified tetrahydrofuran compound) after purification by the method of the present invention is usually 24 wtppm or less, preferably 20 wtppm or less, more preferably 15 wtppm or less, and further preferably 10 wtppm or less.
• ⁇ Purification method of tetrahydrofuran compound> In the method of the present invention, after the raw material tetrahydrofuran compound is brought into contact with an acid catalyst to convert 2,3DHF into a high boiling point compound, the tetrahydrofuran compound and the high boiling point compound are separated by distillation.
• a hydroxy group-containing compound is added to a raw material tetrahydrofuran compound, and 2,3DHF is converted to a high boiling point compound in the presence of an acid catalyst, and then the tetrahydrofuran compound and Separates boiling compounds.
• a high-purity tetrahydrofuran compound having a low OTF content can be obtained without strict separation.
• the high boiling point compound is not particularly limited as long as it is a compound having a boiling point higher than that of THF (boiling point 66 ° C.), preferably higher than the boiling point of OTF (boiling point 80 ° C.), more preferably 110 ° C. or more, and further preferably 200 ° C.
• a compound having a boiling point of 250 ° C. or higher is particularly preferable.
• a material whose boiling point cannot be measured by decomposition of a polymer condensate or the like or has no boiling point is regarded as a high boiling point compound.
• the molecular weight of the high boiling point compound is usually 90 or more, preferably 100 or more, more preferably 120 or more, still more preferably 160 or more, and particularly preferably 180 or more.
• the upper limit of molecular weight is not specifically limited, Usually, it is 1000 or less.
• high-boiling compounds derived from 2,3-dihydrofuran examples include alkoxytetrahydrofuran compounds produced by an addition reaction of 2,3DHF and an alcohol compound, such as dimer or higher compounds obtained by ring-opening polycondensation of 2,3DHF, An acetal compound produced by an addition reaction between 2,3DHF and a diol component is exemplified.
• the acid catalyst is not particularly limited as long as it is an acid catalyst exhibiting acid-base catalysis, but a solid acid catalyst is preferable because neutralization treatment of the solution after contacting the acid catalyst is unnecessary.
• the solid acid catalyst include cation exchange resin, activated clay containing montmorillonite as a main component [eg, Galeon Earth (trade name) manufactured by Mizusawa Chemical Co., Ltd.], sulfated zirconia, fluorosulfonic acid-containing resin [eg, DuPont] Nafion (trade name)], phosphoric acid, heteropolyacid (phosphotungstic acid, phosphomolybdic acid, silicotungstic acid), sulfonic acid compounds and the like are preferable.
• a cation exchange resin and activated clay are more preferable, and a cation exchange resin is more preferable.
• the cation exchange resin examples include acidic cation exchange resins such as strongly acidic cation exchange resins having sulfonic acid as an exchange group and weak acid cation exchange resins having carboxylic acid groups such as methacrylic acid and acrylic acid as exchange groups. Resin.
• the ion exchange resin resin may be selected from gel type, porous type and high porous type.
• a known reaction such as a fixed bed flow reaction format, a suspension bed flow reaction format, a batch reaction format, or the like as a format in which the raw material tetrahydrofuran compound is brought into contact with an acid catalyst, that is, a reaction format in the high boiling treatment of 2,3DHF. Format can be used.
• the reactor that can be used is not particularly limited, and any reactor may be used as long as it is used in the same meaning as the reaction vessel, reaction vessel, reaction kettle, reaction tower, and the like. Industrially, a fixed bed flow reaction system that enables continuous production is preferable.
• the amount of the acid catalyst used is usually 0.05 times or more, preferably 0.1 times or more, more preferably 0, with respect to the amount of raw material tetrahydrofuran compound per hour.
• the upper limit is usually 10 times or less, preferably 5 times or less, more preferably 3 times or less.
• residence time it is usually 3 minutes or longer, preferably 6 minutes or longer, more preferably 30 minutes or longer, and the upper limit is usually 600 minutes or shorter, preferably 300 minutes or shorter, more preferably 90 minutes or shorter. It is.
• this value is too small, the boiling point of 2,3DHF is not sufficiently increased and the replacement frequency of the catalyst is increased.
• the construction cost for the reactor increases, which is industrially disadvantageous.
• the catalyst concentration is usually 0.5 wt% or more, preferably 3 wt% or more, more preferably 5 wt% or more, and the upper limit is usually 50 wt% or less, preferably 30 wt% or less, More preferably, it is 20 wt% or less.
• the residence time is usually 3 minutes or longer, preferably 6 minutes or longer, more preferably 30 minutes or longer, and the upper limit is usually 600 minutes or shorter, preferably 300 minutes or shorter, more preferably 90 minutes or shorter. It is. If these values are too small, the boiling point of 2,3DHF is not sufficiently increased, and the replacement frequency of the catalyst tends to increase. On the other hand, if these values are too large, the construction cost for the reactor increases, which tends to be industrially disadvantageous.
• the water concentration in the liquid phase in the reactor is preferably 4900 wtppm or less, more preferably 3000 wtppm or less, still more preferably 1500 wtppm or less, and particularly preferably 500 wtppm or less. It is. Although a minimum is not specifically limited, It is preferable that it is 10 wtppm or more, More preferably, it is 50 wtppm or more.
• the water concentration in the liquid phase in the reactor is 4900 wtppm or less, preferably 3000 wtppm or less, more preferably 1500 wtppm or less, and particularly preferably 500 wtppm or less. Although a minimum is not specifically limited, It is preferable that it is 10 wtppm or more, More preferably, it is 50 wtppm or more.
• “the water concentration in the liquid phase in the reactor is below a specific value” means that the water concentration in the liquid phase in the reactor during the reaction is kept below a specific value.
• the water concentration in the liquid phase in the reactor may be measured by installing a moisture meter in the reactor, and the amount of water in the raw material tetrahydrofuran compound and the amount of the compound that causes dehydration reaction such as OTF in the raw material. You may obtain
• the reaction temperature is usually 0 ° C. or higher, preferably 15 ° C. or higher, more preferably 40 ° C. or higher, and the upper limit is usually 120 ° C. or lower, preferably 100 ° C. or lower, more preferably 90 ° C. or lower. If this value is too low, it becomes difficult to decompose the by-product OTF, so that the concentration of OTF contained in the reaction solution tends to increase. If this value is too high, it tends to be undesirable from the viewpoint of the heat load on the acid catalyst and the amount of heat related to heating.
• the reaction temperature is the temperature in the reactor, that is, the temperature at which the raw material tetrahydrofuran compound is brought into contact with the acid catalyst to convert 2,3DHF into a high-boiling point compound.
• the reaction pressure is not particularly limited, but the absolute pressure is usually 10 kPa or more, preferably 100 kPa or more, and the upper limit is usually 1000 kPa or less, preferably 500 kPa or less.
• a method for removing the generated high-boiling compounds of 2,3DHF it is preferable to separate them by distillation.
• an evaporator may be used, or a distillation tower having a packed tower, a plate tower, or the like may be used.
• the number of stages of the evaporator and the distillation column is arbitrary, but as a theoretical stage, it is preferably 0 or more, more preferably 1 or more, still more preferably 4 or more, and the upper limit is 100 or less. It is preferable that the number is 10 or less. If the number of stages is greater than 100, the tower becomes too large, and the economics for equipment construction may deteriorate.
• the reflux ratio of the distillation column is usually 0.01 or more, preferably 0.05 or more, more preferably 0.1 or more, and the upper limit is usually 10 or less, preferably 5 or less, more preferably 3 or less. If this value is too small, there is a possibility that sufficient separation cannot be performed, and if it is too large, the amount of heat required for evaporation becomes large, which may deteriorate economically.
• the proportion of the distillate (purified tetrahydrofuran compound) recovered by distillation is preferably 80 wt% or more, more preferably 90 wt% or more, and still more preferably 95 wt% or more with respect to the feed amount of the raw material tetrahydrofuran compound. It is. If this value is too low, the amount of THF contained in the bottom of the evaporator and the bottom of the distillation column increases, and the solution at the bottom of the column may need to be discarded or separately distilled. When discarding the solution at the bottom of the column or adding a separate distillation process, both tend to be industrially disadvantageous. In addition, when using a distillation tower, a distillate is a liquid normally collect
• the method for purifying a tetrahydrofuran compound of the present invention described in detail above is a method for efficiently obtaining a high-purity compound, and the purification method of the present invention is synonymous with the method for producing a tetrahydrofuran compound.
• the tetrahydrofuran compound purified by the method of the present invention is a high-purity compound from which 2,3DHF has been effectively removed, and can be particularly suitably used as a raw material for producing a polyether polyol.
• the method for producing a polyether polyol according to the present invention is characterized in that a ring-opening polymerization reaction is carried out on the tetrohydrofuran compound obtained by the above method in the presence of a ring-opening polymerization reaction catalyst. is there.
• the tetrahydrofuran compound used as a raw material for the ring-opening polymerization reaction is obtained by the above method.
• the method for producing the polyether polyol of the present invention will be described using polyalkylene ether glycol, specifically, polytetramethylene ether glycol as a representative example.
• cyclic ethers such as tetrahydrofuran compounds are easily oxidized and easily form peroxides.
• the peroxide concentration in the tetrahydrofuran compound is not particularly limited, but is usually 50 wtppm or less in order to suppress coloring and side reactions during polymerization.
• the peroxide concentration in the tetrahydrofuran compound can also be controlled by adding an antioxidant such as 2,6-di- (t-butyl) -p-cresol.
• a carboxylic acid anhydride may be used as an auxiliary agent (polymerization reaction initiator).
• Specific examples include carboxylic acid anhydrides derived from aliphatic or aromatic carboxylic acids having 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms.
• the carboxylic acid used as the raw material for the anhydride is preferably a monocarboxylic acid, but a polycarboxylic acid may be used.
• carboxylic acids include aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, maleic acid, and succinic acid; benzoic acid, phthalic acid, naphthalic acid And aromatic carboxylic acids such as Among these, anhydrides derived from aliphatic carboxylic acids are preferable from the viewpoint of price and availability, and acetic anhydride is more preferable from the viewpoints of reactivity and supply and demand of products.
• aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, maleic acid, and succinic acid
• aromatic carboxylic acids such as Among these, anhydrides derived from aliphatic carb
• the amount of carboxylic anhydride used is usually 0.03 mol or more, preferably 0.04 mol or more, more preferably 0.05 mol or more, and still more preferably 0 with respect to a total of 1 mol of the starting tetrahydrofuran compound.
• the upper limit is usually 0.30 mol or less, preferably 0.28 mol or less, more preferably 0.26 mol or less, still more preferably 0.25 mol or less, particularly preferably 0.22 mol. It is as follows.
• the ring-opening polymerization reaction catalyst is not particularly limited as long as it is a catalyst capable of ring-opening polymerization of a tetrahydrofuran compound, but a solid acid catalyst having Lewis acidity is preferably used.
• a solid acid catalyst made of a metal oxide is preferably used.
• the metal is preferably a metal oxide composed of a metal element belonging to Group 3, Group 4, Group 13 or Group 14 of the periodic table (according to IUPAC Inorganic Chemical Nomenclature Revision (1998)), or A composite oxide containing these metal elements is used.
• metal oxides such as yttrium oxide, titania, zirconia, alumina, and silica
• complex oxides such as zirconia silica, hafnia silica, silica alumina, titania silica, and titania zirconia are preferable.
• precipitation may be performed by adding an acid, an alkali, or water, if necessary, to a mixed solution containing one or more metal salts selected from the above metal elements or an alkoxide thereof. And a method of forming a product or gel as a solid acid catalyst precursor. Examples of the method for preparing the precipitate or gel include a coprecipitation method, a sol-gel method, a kneading method, and an impregnation method.
• a metal salt and / or metal alkoxide is supported on a suitable carrier, and a solid is obtained through a process of contacting a basic substance such as an alkali or amine in a solid phase (substantially water-free state).
• a method of obtaining an acid catalyst precursor is preferred.
• the obtained solid acid catalyst precursor is subjected to filtration, washing, and drying, if necessary, and then calcined in an inert gas atmosphere such as nitrogen or argon, or in an oxidizing gas atmosphere such as air or diluted oxygen gas.
• a desired (composite) oxide can be obtained.
• the firing temperature is usually 600 ° C. or higher, preferably 700 ° C. or higher, and the upper limit is usually 1150 ° C. or lower, preferably 1000 ° C. or lower.
• the amount of the ring-opening polymerization reaction catalyst used depends on whether the reaction mode is a fixed bed or a suspension bed, or whether it is a continuous reaction or a batch reaction. In general, it is 0.001 to 50% by weight, preferably 0.01 to 30% by weight, particularly preferably 0.1 to 20% by weight, based on all compounds in the reaction system.
• a polyalkylene ether glycol diester can be obtained by using a tetrahydrofuran compound as a raw material and a carboxylic acid anhydride as an auxiliary.
• Polyalkylene ether glycol diester can be converted to polyalkylene ether glycol by a known method such as hydrolysis or transesterification.
• a known method such as hydrolysis or transesterification.
• THF is used as the tetrahydrofuran compound
• acetic anhydride is used as the carboxylic acid anhydride
• polytetramethylene ether glycol dimethyl ester hereinafter sometimes abbreviated as “PTME”) is used for the fatty acid having 1 to 4 carbon atoms.
• PTMG can be obtained by mixing with a group alcohol and performing transesterification by an alcoholysis reaction in the presence of a transesterification catalyst.
• the reactor for carrying out the ring-opening polymerization reaction is not particularly limited, but those generally used such as a tank type and a tower type may be used.
• the reaction method is not particularly limited as long as it is a known method.
• a specific reaction method a tetrahydrofuran compound, a carboxylic acid anhydride, and a catalyst are respectively measured in a certain amount, and the amount is charged into a reactor and polymerized (batch method); a tetrahydrofuran compound, a carboxylic acid anhydride, and a catalyst are
• a method continuous method in which the reaction solution containing the polyalkylene ether glycol diester which is the target product is continuously withdrawn while being continuously fed so as to exist in a certain amount in each reactor.
• the continuous method is preferable because of excellent productivity.
• the ring-opening polymerization reaction temperature is usually 30 ° C. or higher, preferably 33 ° C. or higher, more preferably 35 ° C. or higher, and the upper limit is usually 50 ° C. or lower, preferably 49 ° C. or lower.
• the ring-opening polymerization reaction temperature in this invention means the liquid temperature in a reactor.
• the reaction pressure may be any pressure that allows the reaction system to maintain a liquid phase, and is usually selected from the range of normal pressure to 10 MPa, preferably normal pressure to 5 MPa.
• the reaction time is not particularly limited, but is usually in the range of 0.1 to 20 hours, preferably 0.5 to 15 hours, from the viewpoint of the yield of polyalkylene ether glycol diester and economy.
• the reaction time here means the time from the time when the reaction temperature rises to the reaction temperature to the start of cooling in the batch system, and in the continuous system, the reaction time of the polymerization reaction liquid in the reactor. It means the residence time.
• an unreacted raw material recovery step a removal and hydrolysis step of the obtained polyalkylene ether glycol diester, a catalyst regeneration step, and the like may be added after the reactor.
• the catalyst and the reaction solution are separated by filtration, and the unreacted raw material is distilled off from the reaction solution, whereby only the polymer can be easily obtained. Furthermore, the catalyst after the reaction can be easily recovered by thoroughly washing and then burning the attached organic matter.
• a reaction liquid containing polyalkylene ether glycol diester is added to the gas-liquid contact device. It is preferable to include a step of supplying and separating and recovering unreacted raw materials. These unreacted raw material recovery steps may be used singly or in combination.
• a gas-liquid contact apparatus means the apparatus used in the process which makes an inert gas contact with the reaction liquid containing polyalkylene glycol diester.
• the unreacted raw material means a polyoxyalkylene glycol having a number average molecular weight lower than that of the target polyalkylene ether glycol.
• a di- to hexamer polyalkylene ether glycol and its diester are also included. Including.
• the diol component obtained in the above-described unreacted raw material recovery step may be used.
• polytetramethylene ether glycol is produced from THF as a raw material
• dimer or hexamer polytetramethylene ether glycol diester or dimer or hexamer polytetramethylene ether glycol is separated in the unreacted raw material recovery step to obtain a diol.
• a method of adding to a THF compound as a component is preferably used.
• the obtained unreacted raw material is a diester of 2 to 6-mer polytetramethylene ether glycol, it may be further converted into a diol component through a hydrolysis step and then added to the THF compound.
• the gas-liquid contact device is not particularly limited, but as a gas-liquid contact device of a type that disperses the liquid in the gas continuous phase, for example, a packed tower, a spray tower, a scrubber, a wet wall column, etc .; a type of gas dispersed in the liquid continuous phase
• a gas-liquid contact device include a bubble tower, a plate tower, and a bubble stirring tank. These may be used alone or in combination.
• a gas-liquid contact device of a type in which a liquid is dispersed in a gas continuous phase is preferable because a liquid / gas ratio is small and a residence time can be shortened, and a heat deterioration of a polymer can be avoided.
• packed towers More preferred are packed towers, spray towers and scrubbers capable of increasing the gas-liquid contact area, and packed towers that are particularly easy to control tend to be industrially advantageous.
• the packing in the packed tower may be an irregular packing such as a Raschig ring or a pole ring or a regular packing.
• the inert gas used in the gas-liquid contact device preferably includes at least one selected from nitrogen, argon, and carbon dioxide, and among these, nitrogen is more preferable.
• the charged volume ratio of the aeration gas to the charged liquid amount varies depending on the tower temperature and the number of stages in the tower, but is usually 10 or more and 100 or less. An excessive volume ratio tends to be industrially disadvantageous because it leads to loss of aeration gas.
• the number of column stages depends on the residence time, but 5 to 30 stages are preferable.
• the pressure is usually 10 to 200 kPa, preferably 20 to 100 kPa
• the treatment temperature is usually 100 to 200 ° C., preferably 140 to 180 ° C. If the treatment temperature is too low, there is a tendency that the remaining unreacted raw material cannot be sufficiently separated. If the treatment temperature is too high, decomposition of the carboxylic acid anhydride is likely to occur, and coloring derived from the decomposition product is more easily manifested. Tend.
• the treatment time is preferably 10 to 240 minutes, more preferably 15 to 180 minutes, and particularly preferably 30 to 120 minutes. If the treatment time is too short, the unreacted raw materials tend not to be sufficiently separated. If the treatment time is too long, the decomposition of the carboxylic acid anhydride proceeds, and the color derived from the decomposition products tends to become obvious.
• the material inside the gas-liquid contact device is not particularly limited, and a known material can be used, and examples thereof include SUS, Hastelloy (trade name), titanium, and glass. Among these, SUS and Hastelloy (trade name) are preferable from the viewpoint of corrosion resistance. More specifically, examples include SUS304, SUS316, SUS316L, SUS317, SUS317L, SUS329J4L, and the like.
• the degree of coloration of the polyalkylene ether glycol diester obtained in the present invention can be indicated by the Hazen color number (APHA value) defined in the standard of the Hazen color number American Public Health Association.
• the APHA value is not particularly limited, but is usually 35 or less, preferably 30 or less, more preferably 25 or less, and still more preferably 15 or less.
• the Hazen color number is a value measured using the method described in the [Example] section.
• the acid value of the polyalkylene ether glycol diester obtained in the present invention is not particularly limited, but is usually 1.0 mgKOH / g or less, preferably 0.5 mgKOH / g or less, more preferably 0.3 mgKOH / g or less, and still more preferably Is 0.1 mg KOH / g or less.
• the acid value is the number of mg of potassium hydroxide required to neutralize the acid contained in 1 g of the sample.
• the polyalkylene ether glycol diester obtained in the present invention can be converted to polyalkylene ether glycol by a known method such as hydrolysis or transesterification.
• the transesterification catalyst is not particularly limited as long as it is a known one used in hydrolysis and transesterification reactions.
• alkali metal alkoxides such as lithium, sodium, potassium, cesium, and rubidium are used. Of these, sodium and potassium alkoxides are preferred.
• sodium methoxide, sodium ethoxide, sodium isopropoxide, potassium methoxide, potassium ethoxide, potassium isopropoxide and the like can be mentioned. Of these, sodium methoxide is more preferred because of its versatility and low cost.
• the hydrolysis reaction or transesterification reaction can usually be carried out at normal pressure or under pressure.
• the reaction pressure is usually 0.1 to 2.0 MPa, preferably 1.0 to 1.5 MPa, and the reaction temperature is usually in the range of 60 to 180 ° C.
• polyalkylene ether glycol The APHA value and acid value of polyalkylene ether glycol are the same as those in the above polyalkylene ether glycol diester.
• polyalkylene ether glycol obtained from the polyalkylene ether glycol diester can be suitably used for applications such as elastic fibers, thermoplastic polyester elastomers, thermoplastic polyurethane elastomers, and coating materials.
• Comparative Examples 1 and 2 and Examples 1 to 4 and 6 to 8 below show the effects of 2,3DHF and water mainly contained in the PBT byproduct THF compound on the purification process of the THF compound and
• Comparative Example 3 and Example 5 are experimental examples using a PBT by-product THF compound (actual liquid). Therefore, the technical scope of the present invention is not limited by the following experimental examples unless it exceeds the gist.
• a strong acidic cation exchange resin (Diaion PK216LH) manufactured by Mitsubishi Chemical Corporation was filled into a cylindrical glass reactor having an inner diameter of 20 mm in 30 cc, and THF manufactured by Mitsubishi Chemical Corporation was passed through it for 6 hr at a flow rate of 150 cc / hr. Immediately after finishing this treatment, the water content in THF obtained from the reactor outlet was about 100 wtppm. A reactor in which this treatment was performed as a pretreatment was used.
• Hazen color number The degree of coloration of the polyalkylene ether glycol diester (specifically PTME) was represented by the Hazen color number (APHA value) defined in the standard of the Hazen color number.
• the Hazen color number was obtained by using a standard solution prepared by diluting APHA color number standard solution (No. 500) manufactured by Kishida Chemical Co., Ltd., and colorimetrically according to JIS K0071-1 (1998).
• As the color difference meter a colorimetric color difference meter ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd. was used, and measurement was performed under the condition of cell thickness: 10 mm.
• the number average molecular weight (Mn) of the polyalkylene ether glycol diester (specifically, PTME) is determined by preparing a tetrahydrofuran solution of PTME and then using a GPC apparatus [product name “HLC-8220” manufactured by Tosoh Corporation, column: Tskel SuperHZM-N ( 4))].
• a GPC apparatus [product name “HLC-8220” manufactured by Tosoh Corporation, column: Tskel SuperHZM-N ( 4)
• Ring-opening polymerization catalyst As a catalyst for the ring-opening polymerization reaction of THF, a 27.2% zirconia nitrate aqueous solution is impregnated with CARiACTQ15 (registered trademark) (silica support manufactured by Fuji Silysia Chemical Ltd.), dried, and then neutralized with an aqueous ammonium bicarbonate solution. -After washing, what was dried and fired at 900 ° C was used.
• Example 1 2,3DHF manufactured by Wako Pure Chemical Industries, Ltd. was added to THF manufactured by Mitsubishi Chemical Corporation to prepare 1000 ppm by weight. The water concentration at this time was about 100 wtppm.
• This raw material was circulated at 30 cc / hr in a fixed bed reactor that had been pretreated at 60 ° C. and 0.2 MPa. The liquid 24 to 48 hours after the start of the reaction was stored in the product tank. In the reaction liquid stored in the product tank, 2,3DHF was 0 wtppm, OTF was 0 wtppm, and water was 100 wtppm.
• Examples 2 to 4 A raw material having the composition shown in Table 1 was prepared by adding 2,3DHF manufactured by Wako Pure Chemical Industries, Ltd. to THF manufactured by Mitsubishi Chemical Corporation. In the same manner as in Example 1, this raw material was passed through a fixed bed reactor that had been pretreated and then distilled to distill THF, and a polymerization reaction was carried out using this distillate. The quality of the obtained PTME was confirmed. Table 1 shows the reaction temperature of the fixed bed, the amount of OTF produced after the reaction, the composition of the main distillate (after simple distillation), and the quality of PTME.
• Example 5 Using the PBT by-product THF compound having the composition shown in Table 1 as a raw material, it was circulated through the fixed bed reactor after the pretreatment and distilled to distill THF in the same manner as in Example 1. A polymerization reaction was carried out using the liquid, and the quality of the obtained PTME was confirmed. Table 1 shows the reaction temperature of the fixed bed, the amount of OTF produced after the reaction, the composition of the distillate (after simple distillation), and the quality of PTME.
• Example 6 Wako Pure Chemical Industries, Ltd. hexanol was added to 3000 wtppm (molar ratio to 23DHF: 2.06) by adding 2,3DHF manufactured by Mitsubishi Chemical Co., Ltd. to 1000 wtppm. Prepared. The water concentration at this time was about 100 wtppm.
• This raw material was circulated at 30 cc / hr in a fixed bed reactor after pretreatment at 40 ° C. and 0.2 MPa. After the start of the reaction, a liquid of 24-48 hours was stored in the product tank. In the reaction liquid stored in the product tank, 2,3DHF was 0 wtppm, OTF was 0 wtppm, and water was 100 wtppm.
• Example 7 To the THF prepared by Mitsubishi Chemical Corporation, 2,3DHF manufactured by Wako Pure Chemical Industries, Ltd. was added to prepare 1000 wtppm, and an oligomer having an average molecular weight of 250 composed of PTMG dimer to hexamer was added to 2500 wtppm (23 DHF To a molar ratio of 0.70). The water concentration at this time was about 200 wtppm.
• This raw material was circulated at 30 cc / hr in a fixed bed reactor after pretreatment at 25 ° C. and 0.2 MPa. After the start of the reaction, a liquid of 24 to 48 hours was stored in the product tank.
• the 2,3DHF concentration in the reaction liquid stored in the product tank was 0 wtppm, OTF was 37 wtppm, and water was 200 wtppm. 1000 g of this reaction solution was put into a glass pear-shaped flask and heated at a bath temperature of 100 ° C. for 2 hours under normal pressure while bubbling nitrogen at a flow rate of 30 cc / min. THF was distilled off.
• Example 8 To the THF prepared by Mitsubishi Chemical Corporation, 2,3DHF manufactured by Wako Pure Chemical Industries, Ltd. was added to prepare 1000 wtppm, and an oligomer having an average molecular weight of 250 composed of PTMG dimer to hexamer was added to 2500 wtppm (23 DHF To a molar ratio of 0.70). The water concentration at this time was about 200 wtppm.
• This raw material was circulated at 30 cc / hr in a fixed bed reactor after pretreatment at 60 ° C. and 0.2 MPa. After the start of the reaction, a liquid of 24-48 hours was stored in the product tank.
• the 2,3DHF in the reaction liquid stored in the product tank was 0 wtppm, OTF was 0 wtppm, and water was 200 wtppm. 1000 g of this reaction solution was put into a glass pear-shaped flask and heated at a bath temperature of 100 ° C. for 2 hours under normal pressure while bubbling nitrogen at a flow rate of 30 cc / min. THF was distilled off.
• a highly pure THF compound can be obtained from a THF compound containing 2,3DHF, and PTME produced using the obtained purified THF compound as a raw material can be obtained. It is possible to significantly improve the hue. Moreover, since the separation load concerning purification can be reduced by lowering the moisture concentration in the raw material and suppressing the generation amount of OTF, it is possible to reduce the cost of equipment and the amount of steam used.

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