JPH04277522A - Production of polyoxytetramethylene glycol - Google Patents

Abstract

PURPOSE:To provide a process for producing PTMG from THF by using an inexpensive solid super acid catalyst which is free from antimony pentafluoride and easy to recover and recycle. CONSTITUTION:A process for producing polyoxytetramethylene glycol comprising polymerizing tetrahydrofuran in the presence of a solid super acid catalyst comprising a compound metal oxide selected from the group consisting of the metal oxides of the general formula: MxOy (wherein x and y are each an integer of 1-3) and ammonium hydrogen-fluoride (NH4F.HF). Polyoxytetramethylene glycol can be produced efficiently in good yields by using a solid super acid catalyst which can easily be recovered and recycled and is more inexpensive as a polymerization catalyst.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for producing polyoxytetramethylene glycol (hereinafter referred to as PTMG) by polymerizing tetrahydrofuran (hereinafter referred to as THF) using an inexpensive solid super acid catalyst as a polymerization catalyst. .

0002

[Prior Art] PTMG is an industrially useful polymer used as the main raw material for polyurethane, polyether ester, and polyether (ester) amide used in spandex, elastomers, artificial leather, etc., as well as in surfactants, pressure fluids, etc. In recent years, it has attracted particular attention as an engineering material and medical polymer material, mainly in the elastomer field.

[0003] PTMG is industrially produced by polymerizing THF, but this polymerization reaction is a cationic polymerization and does not proceed easily. Large protic acids and Lewis acids have been used, often with the addition of cocatalysts. Typical examples of the former are fluorosulfonic acid and fuming sulfuric acid, and examples of the latter are:
Examples include perchloric acid-acetic anhydride, BF3-HF-acetic anhydride, and napfion (fluorinated sulfonic acid resin)-acetic anhydride.
These are implemented industrially.

[0004] A common and fatal drawback of these conventional methods is that PTMG cannot be produced all at once from THF. That is, both ends of PTMG must be hydroxyl groups, but in the conventional method, the end groups immediately after polymerization are -
It is terminated as SO3H group or -OCOCH3 group, which is hydrolyzed by adding water or alkaline water,
This is a two-step method in which both ends are hydroxyl groups.

[0005] A polymerization method using fuming sulfuric acid as a catalyst is also known, but it is used for applications where the molecular weight is limited to around 1000, but water must be added in the post-treatment, making it extremely difficult to recycle the catalyst. (Tokuko Sho 52-
32680 etc.). Additionally, methods using heteropolyacid catalysts or solid super strong acids are known as methods for polymerizing THF without using a cocatalyst and producing PTMG having terminal OH groups all at once, but the former is expensive. Since a high concentration of a heteropolyacid catalyst is used, care must be taken to recover the catalyst.

Furthermore, since the heteropolyacid catalyst is slightly dissolved in THF, the process becomes complicated even though it is a one-step method in order to separate a trace amount of the heteropolyacid catalyst from PTMG when producing PTMG. (Tokuko Showa 6)
3-30931). Furthermore, the latter also uses expensive antimony pentafluoride as a catalyst, and great care must be taken to recover the catalyst (Japanese Patent Laid-Open No. 63-35623).

[0007]

[Problems to be Solved by the Invention] Most of these conventional techniques cannot produce PTMG from THF all at once, and the manufacturing process is complicated, and the method for producing PTMG from THF at once is difficult. The method also uses an expensive catalyst, and furthermore, the catalyst is slightly soluble in THF, making catalyst recovery complicated. The conventionally used solid super strong acid catalyst supports antimony pentafluoride as one of its components, but this is an extremely expensive chemical. Furthermore, due to toxicity and corrosivity, skill is required when supporting it on a carrier.

[0008]

OBJECTS OF THE INVENTION An object of the present invention is to develop a method for producing PTMG from THF using an inexpensive solid superacid catalyst that is easy to recover and recycle and does not contain antimony pentafluoride.

[0009]

[Means for solving the problem] That is, general formula: Mx
In the presence of a solid super acid catalyst consisting of a composite metal oxide selected from the group of metal oxides represented by Oy (x, y are integers of 1 to 3) and ammonium hydrogen fluoride (NH4F.HF), THF is PTMG characterized by being polymerized
This is a manufacturing method.

The composite metal oxide used as a catalyst in the present invention is aluminum oxide (Al2
O3), silicon dioxide (SiO2), titanium dioxide (T
iO2), zirconium dioxide (ZrO2), tungsten trioxide (WO3), zinc oxide (ZnO), etc., for example, Al2O3-Si
O2, SiO2-TiO2, SiO2-ZrO2, Ti
There are O2-ZrO2 and the like.

These composite metal oxides are produced by precipitating the alkoxide, chloride, or oxychloride of each metal with aqueous ammonia as a composite metal oxide, thoroughly washing the precipitate, drying it at about 100°C, and pulverizing it. (200~500
400°C to 600°C, preferably 4
It is obtained by firing at 50°C to 500°C. The molar composition of the metal is in the range of 1:9 to 9:1, and adjustment of the molar composition is determined by the metal composition in the metal alkoxide, chloride or oxychloride used.

Examples of metal alkoxides include tetraethylorthosilicate (Si(OC2H5)4) and aluminum isopropoxide (Al[OCH(CH3)2]3).
), examples of chlorides include titanium tetrachloride (TiCl4) and zinc chloride (ZnCl2), and examples of oxychlorides include zirconium oxychloride (ZrOCl2.8H2O).

The supporting ratio of ammonium hydrogen fluoride to the metal oxide represented by MxOy (x, y are integers of 1 to 3) is not particularly defined, but if the supporting ratio is too low, the polymerization activity will decrease, so the use of a catalyst may be difficult. This is not preferable because the amount increases and the polymerization time becomes longer. Therefore, it is preferably used at a loading rate of 2 wt% or more. The concentration of the ammonium hydrogen fluoride aqueous solution is preferably 1 to 1.5 wt%, and after immersing the metal oxide represented by MxOy (x and y are integers of 1 to 3) for 7 days or more, it is evaporated to dryness on a hot water bath. It is then dried at 120°C for 24 hours.

In this way, for example, Al2O3-Si
O2-NH4F・HF, SiO2-TiO2-NH4F
・Solid super strong acids such as HF can be obtained. In the present invention, when THF is polymerized, the solid superacid can be used in two reaction methods.

One is to combine 1,4-butanediol or/and water with THF or 1,4-butanediol in the presence of a solid superstrong acid.
- A method for producing PTMG in a one-step reaction by polymerizing oligomers of butanediol or/and water, THF, and PTMG. THF is polymerized using a carboxylic acid anhydride such as acetyl chloride, propionyl chloride, carboxylic acid chloride such as butyryl chloride, diketene, or fuming sulfuric acid as a cocatalyst, and the terminal group is -SO3H group or This is a method of producing PTMG through a two-step reaction in which a polymerization intermediate terminated as -OCOCH3 group is produced, and then water or alkaline water is added to the intermediate to hydrolyze it to form hydroxyl groups at both ends.

The amount of catalyst varies depending on the reaction method (one-stage or two-stage method), the intended polymerization conditions, the molecular weight of PTMG, and the co-catalyst used. Polymerization temperature is -20℃~1
The temperature is in the range of 50°C, but for carrying out polymerization in a one-step process, a temperature in the range of room temperature to 150°C is preferable in order to develop sufficient catalytic activity. In addition, when using a co-catalyst, -20℃~
It should be around room temperature. The polymerization reaction is carried out for 1 to 15 hours, usually 3 to 10 hours, after addition of the catalyst.

[0017] As for the reaction format, commonly used ones such as tank type and column type are used. It may be carried out either batchwise or continuously. Specifically, in the one-step method, 1,4-butanediol or/and water and THF, or 1,4-butanediol or/and water and THF
and PTMG oligomer and a solid super acid catalyst are placed in a reactor and polymerized (batch method), 1,4-
butanediol or/and water and THF or 1,
4-butanediol or/and water and THF and PTMG
A method in which the oligomer and the solid super strong acid catalyst are continuously charged into a reactor so as to have an appropriate residence time, and the reaction crude liquid containing the solid super strong acid catalyst is continuously withdrawn, or
A solid super acid catalyst is sealed in a reactor, and 1,4-
butanediol or/and water and THF or 1,
4-butanediol or/and water and THF and PTMG
The reaction is carried out by one of two methods (continuous method) in which the oligomers are continuously charged into a reactor and the reaction crude liquid is continuously withdrawn so as to have an appropriate residence time.

In addition, in the two-stage method, THF and a solid super strong acid catalyst are charged into a reactor, and a cocatalyst is continuously charged into the reactor while stirring to carry out polymerization (batch method);
A method in which THF, a solid super strong acid catalyst, and a cocatalyst are continuously charged into a reactor so as to have an appropriate residence time, and a reaction crude solution containing the solid super strong acid catalyst is continuously withdrawn, or a solid super strong acid The catalyst is sealed in the reactor and THF
This is carried out by one of two methods (continuous method), in which the reactor and cocatalyst are continuously charged into a reactor so as to have an appropriate residence time, and the reaction crude liquid is continuously withdrawn.

The reaction method should be selected in consideration of the amount of PTMG produced, the amount of polymerization heat removed, the properties of the catalyst, etc. Polymerization reactions are usually carried out at normal pressure due to equipment costs, etc.
There is almost no advantage in carrying out the reaction under pressure, but if the reaction is carried out at a temperature above the boiling point of THF without using an inert solvent for a high boiling point reaction, the reaction may be carried out under pressure.

The solid superacid is removed from the catalyst suspension polymerization solution obtained by the above method by filtration or centrifugation, and the recovered catalyst is reused as it is. Unreacted 1,4-butanediol, water, and THF from the reaction crude liquid after catalyst separation
A THF polymer can be obtained by distilling off the co-catalyst, but in order to finally produce PTMG from the co-catalyst polymer, the terminal ester group is hydrolyzed by adding water or alkaline water. The terminal is changed to a hydroxyl group, purified in the presence of an appropriate organic solvent such as benzene, toluene, xylene, n-butanol, di-isopropyl ether, etc., and the solvent is recovered.
Perform dehydration.

The solid superacid separated and recovered by filtration naturally retains its polymerization activity and is recycled for use. The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is in no way limited by these Examples and Comparative Examples. In the following examples and comparative examples, the number average molecular weight MN is P based on JIS K1557-1970.
It was determined by the OH value of TMG. Further, the acid strength (pKa) of the prepared solid superstrong acid is a value determined by an indicator method using a Hammett indicator.

[0022]

[Example 1] Aluminum isopropoxide (Al[O
CH(CH3)2]3) and tetraethyl orthosilicate (Si(OC2H5)4) were dissolved in a large excess of water at a molar ratio of 1:3, and neutralized with concentrated ammonia water while stirring.
Hydrolysis yielded a mixed precipitate of each hydroxide. This precipitate suspension was filtered and thoroughly washed with water until the pH of the filtrate became neutral. The obtained paste-like metal hydroxide containing water was dried at 100° C. for a day and night to obtain a milky white lumpy solid. After crushing this, it was sieved and the powder of 300-400 mesh was calcined at 450℃ for 4 hours to produce white SiO2
-Al2O3 powder was obtained.

Next, in a plastic container having a content of 500 ml, 1.15 g of ammonium hydrogen fluoride was dissolved in 100 ml of pure water, and 15 g of the silica-alumina obtained by the above method was immersed for 7 days. Furthermore, after evaporating to dryness on a hot water bath, it was dried in an oven at 120°C for 24 hours.
A SiO2-Al2O3 catalyst supporting ammonium hydrogen fluoride (supporting rate 7.6 wt%) was obtained.

A Hammett indicator was used to determine whether the acid was a super strong acid. That is, 0.5 g of the prepared catalyst was calcined at 550° C. for 3 hours in a stream of dry air, then divided into 5 portions and each portion was placed in a test tube containing 3 ml of a sufficiently dehydrated sulfuryl chloride solution. Next, one of the following five types of Hammett indicators
A few drops of % benzene solution were put into each test tube, shaken lightly several times, and left to stand to visually observe the presence or absence of discoloration on the catalyst surface.

Hammett indicator m-nitrotoluene (pK
a=11.99), nitrobenzene (pKa=-12.
14), p-fluoronitrobenzene (pKa=-12
．． 44), p-chloronitrobenzene (pKa=-12
．． 70), m-chloronitrobenzene (pKa=-13
．． 16), all indicators changed color. From this, the acid strength of the prepared catalyst is H0<-13
．． 16, and the acid strength of 100% sulfuric acid (H0 = -11.
93).

[0026]

[Example 2] Capacity 300 equipped with stirring device and reflux condenser
100ml of THF in a jacketed glass flask.
Example 1
30 g of solid super strong acid prepared by the method described above was added, and a polymerization reaction was carried out for 10 hours. After the polymerization reaction, the reaction crude liquid is filtered to separate the catalyst, THF is distilled off from the filtrate, and the mixture is dried under reduced pressure. 30.
5g of PTMG was obtained. The number average molecular weight determined from the OH value was 6900.

[0027]

[Example 3] Capacity 300 equipped with stirring device and reflux condenser
100ml of THF in a jacketed glass flask.
g and 1.0 g of 1,4-butanediol, and
℃ under stirring, solid superacid 30 prepared by the method of Example 1.
g was added thereto, and the polymerization reaction was carried out for 10 hours. After the polymerization reaction,
The reaction crude liquid was filtered to separate the catalyst, and THF was distilled off from the filtrate and dried under reduced pressure to obtain 39.7 g of PTMG. The number average molecular weight determined from the OH value was 2,870.

[0028]

[Example 4] Capacity 300 equipped with stirring device and reflux condenser
Add 10 ml of THF to a jacketed glass flask.
0g and 10g of the solid super strong acid prepared by the method of Example 1 were charged, and while stirring at 10°C, 14.2g of acetic anhydride was added over 10 minutes, and a polymerization reaction was carried out for 5 hours. After the reaction is completed, the solid superacid catalyst is separated by filtration.

Unreacted THF was separated from the reaction crude solution after catalyst separation, and 60 g of n-butanol and 60 g of a 20% aqueous sodium hydroxide solution were added to carry out a hydrolysis reaction for 2 hours under reflux cooling. After cooling, the mixture was allowed to stand still for liquid separation, the lower aqueous layer was extracted, 50 g of water was added to the upper organic layer, and the mixture was stirred and washed with water. After repeating this water washing operation three times, n-butanol/H2O was distilled off from the organic layer and dried under reduced pressure to obtain 79.3 g of PTMG with a number average molecular weight of 1800 as a canned product.

[0030]

[Example 5] Tetraethyl orthosilicate (Si(O
C2H5)4) and zirconium oxychloride ZrOCl2
-8H2O was dissolved in a large excess of water at a molar ratio of 1:9, neutralized with concentrated ammonia water under stirring, and hydrolyzed to obtain a mixed precipitate of each hydroxide. This precipitate suspension was filtered and thoroughly washed with water until the pH of the filtrate became neutral. The obtained paste-like metal hydroxide containing water was dried at 100° C. for a day and night to obtain a milky white lumpy solid. After pulverizing this, sieve it to obtain 300-400 mesh powder.
It was fired at 0°C for 1 hour to obtain white SiO2-ZrO2 powder.

Next, in a plastic container with a capacity of 500 ml, 1.15 g of ammonium hydrogen fluoride was dissolved in 100 ml of pure water, and 15 g of the silica/alumina obtained by the above method was immersed for 7 days. Furthermore, after evaporating to dryness on a hot water bath, it was dried in an oven at 120°C for 24 hours.
A SiO2-ZrO2 catalyst supporting ammonium hydrogen fluoride was obtained. The acid strength of the prepared catalyst was measured using a Hammett indicator, and it was shown that H0<-13.16, which was 17 times or more the acid strength of 100% sulfuric acid (H0 = -11.93).

[0032]

[Example 6] Capacity 300 equipped with stirring device and reflux condenser
Add 10 ml of THF to a jacketed glass flask.
0 g and 10 g of a solid super strong acid prepared by the method of Example 5 were charged, and while stirring at 10° C., 14.2 g of acetic anhydride was added over 10 minutes, and a polymerization reaction was carried out for 5 hours. After the reaction is completed, the solid superacid catalyst is separated by filtration. After separating the catalyst, unreacted THF was separated from the reaction crude liquid, and 60 g of n-butanol was added.
and 60 g of a 20% aqueous sodium hydroxide solution were added, and a hydrolysis reaction was carried out for 2 hours under reflux cooling.

After cooling, the mixture was allowed to stand still for liquid separation, the lower aqueous layer was extracted, and 50 g of water was added to the upper organic layer, followed by stirring and washing with water. After repeating this water washing operation three times in the same way, n.
- By distilling off butanol/H2O and drying under reduced pressure, PTMG with a number average molecular weight of 1250 is produced as a canned product of 74
．． 5g was obtained.

[0034]

[Example 7] Tetraethyl orthosilicate (Si(O
C2H5)4) and titanium chloride (TiCl2) are dissolved in a large excess of water at a molar ratio of 1:9, neutralized with concentrated ammonia water under stirring, and hydrolyzed to precipitate a mixture of each hydroxide. I got something. This precipitate suspension was filtered and thoroughly washed with water until the pH of the filtrate became neutral. The obtained paste-like metal hydroxide containing water was dried at 100° C. for a day and night to obtain a milky white lumpy solid.

[0035] After crushing this, sieve it and
The 00 mesh powder was fired at 450°C for 1 hour to obtain white SiO2-TiO2 powder. Then, the internal capacity is 500
ml plastic container, 1.15 g of ammonium hydrogen fluoride was dissolved in 100 ml of pure water, and 15 g of silica/alumina obtained by the above method was immersed for 7 days. Furthermore, after evaporating to dryness on a hot water bath, it was dried in an oven at 120°C for 24 hours to form a SiO
-TiO2 catalyst was obtained.

As a result of measuring the acid strength of the prepared catalyst using a Hammett indicator, H0<-12.70, 100
% sulfuric acid (H0=-11.93).

[0037]

[Example 8] Capacity 300 equipped with stirring device and reflux condenser
Add 10 ml of THF to a jacketed glass flask.
0 g and 10 g of a solid super strong acid prepared by the method of Example 7 were charged, and while stirring at 10° C., 14.2 g of acetic anhydride was added over 10 minutes, and a polymerization reaction was carried out for 5 hours. After the reaction is completed, the solid superacid catalyst is separated by filtration. After separating the catalyst, unreacted THF was separated from the reaction crude liquid, and 60 g of n-butanol was added.
and 60 g of a 20% aqueous sodium hydroxide solution were added, and a hydrolysis reaction was carried out for 2 hours under reflux cooling.

After cooling, the mixture was allowed to stand still for liquid separation, the lower aqueous layer was extracted, and 50 g of water was added to the upper organic layer, followed by stirring and washing with water. After repeating this water washing operation three times in the same way, n.
- By distilling off the butanol/H2O and drying under reduced pressure, PTMG with a number average molecular weight of 850 is produced as a canned product of 65.
7g was obtained.

[0039]

[Example 9] Titanium chloride (TiCl2) and zirconium oxychloride ZrOCl2.8H2O were dissolved in a large excess of water at a molar ratio of 1:9, and each was neutralized with concentrated ammonia water and hydrolyzed with stirring. A mixed precipitate of hydroxides was obtained. This precipitate suspension was filtered and thoroughly washed with water until the pH of the filtrate became neutral. The obtained paste-like metal hydroxide containing water was dried at 100° C. for a day and night to obtain a milky white lumpy solid. After crushing this, sift it and
0 mesh powder was fired at 450°C for 1 hour to form a white T.
iO2-ZrO2 powder was obtained.

Next, in a plastic container with a content capacity of 500 ml, 1.5 g of ammonium hydrogen fluoride was added to 1 g of pure water.
00 ml of the silica/alumina obtained by the above method was immersed for 7 days. Further, the mixture was evaporated to dryness on a hot water bath, and then dried in an oven at 120°C for 24 hours to obtain a TiO2-ZrO2 catalyst supported on ammonium hydrogen fluoride.

As a result of measuring the acid strength of the prepared catalyst using a Hammett indicator, H0<-13.16, 100
% sulfuric acid (H0=-11.93).

[0042]

[Example 10] Capacity 30 equipped with stirring device and reflux condenser
Add 1 ml of THF to a 0 ml jacketed glass flask.
00g and 10g of the solid super strong acid prepared by the method of Example 9 were charged, and while stirring at 10°C, 14.2g of acetic anhydride was added over 10 minutes, and a polymerization reaction was carried out for 5 hours.

After the reaction is completed, the solid superacid catalyst is separated by filtration. Separating unreacted THF from the reaction crude liquid after catalyst separation,
Furthermore, 60 g of n-butanol and 60 g of 20% aqueous sodium hydroxide solution were added, and a hydrolysis reaction was carried out for 2 hours under reflux cooling. After cooling, the mixture was allowed to stand still for liquid separation, the lower aqueous layer was extracted, 50 g of water was added to the upper organic layer, and the mixture was stirred and washed with water. After repeating this water washing operation three times, n-butanol/H2O is distilled off from the organic layer and dried under reduced pressure to produce PTMG with a number average molecular weight of 980 as a canned product.
．． 3g was obtained.

[0044]

[Comparative Example 1] Titanium chloride (TiCl2) and zirconium oxychloride ZrOCl2.8H2O were dissolved in a large excess of water at a molar ratio of 1:9, and each was neutralized with concentrated ammonia water and hydrolyzed with stirring. A mixed precipitate of hydroxides was obtained. This precipitate suspension was filtered and thoroughly washed with water until the pH of the filtrate became neutral. The obtained paste-like metal hydroxide containing water was dried at 100° C. for a day and night to obtain a milky white lumpy solid. After crushing this, sift it and
0 mesh powder was baked at 450℃ for 1 hour to form a white T.
iO2-ZrO2 powder was obtained.

Next, the above TiO2-ZrO2 powder was placed in a U-shaped reaction tube, connected to an antimony pentafluoride (SbF5) vaporizer and a vacuum pump system, and after the system was vacuum degassed, Sb
The operation of introducing F5 vapor and then evacuation again at 50°C was repeated four times. Finally, after being left saturated with SbF5 vapor at room temperature for 4 hours, it was evacuated at 50° C. and 5 mmHg for 1 hour. As a result of measuring the acid strength of the prepared catalyst using a Hammett indicator, H0<-13.16, which is 17% higher than the acid strength of 100% sulfuric acid (H0=-11.93).
It was shown that it is more than double.

Comparing Comparative Example 1 and Example 9, it is found that the solid super strong acid supported on ammonium hydrogen fluoride (NH4F.HF) and the solid super strong acid supported on expensive antimony pentafluoride (SbF5) have the same acid strength. It shows that you have it.

[0047]

[Comparative Example 2] Capacity 300 equipped with stirring device and reflux condenser
Add 10 ml of THF to a jacketed glass flask.
0 g and 10 g of a solid super strong acid prepared by the method of Comparative Example 1 were charged, and while stirring at 10° C., 14.2 g of acetic anhydride was added over 10 minutes, and a polymerization reaction was carried out for 5 hours.

After the reaction is completed, the solid superacid catalyst is separated by filtration. Separating unreacted THF from the reaction crude liquid after catalyst separation,
Furthermore, 60 g of n-butanol and 60 g of 20% aqueous sodium hydroxide solution were added, and a hydrolysis reaction was carried out for 2 hours under reflux cooling. After cooling, the mixture was allowed to stand still for liquid separation, the lower aqueous layer was extracted, 50 g of water was added to the upper organic layer, and the mixture was stirred and washed with water.

After repeating this water washing operation three times,
By distilling off n-butanol/H2O from the organic layer and drying under reduced pressure, 84.7 g of PTMG having a number average molecular weight of 960 was obtained as a canned product. Comparing Comparative Example 2 and Example 10, ammonium hydrogen fluoride (NH4F・HF)
Supported solid super acid and expensive antimony pentafluoride (SbF5)
) shows that the supported solid superacid has equivalent reaction results.

[0050]

[Example 11] Capacity 30 equipped with stirring device and reflux condenser
Add 1 ml of THF to a 0 ml jacketed glass flask.
00g and 5g of the solid super strong acid prepared by the method of Example 1 were charged, and while stirring at 0°C, 20g of 25% oleum was added over about 60 minutes, and the polymerization reaction was further carried out for 4 hours. After the reaction is completed, the solid superacid catalyst is separated by filtration. After separating the catalyst, 110 g of water was added to the filtrate to separate unreacted THF, and a hydrolysis reaction was carried out for 2 hours under reflux cooling. After cooling and standing, the sulfuric acid water in the lower layer was extracted, and 60 g of toluene and 50 g of water were added to the upper organic layer, followed by stirring and washing with water.

After repeating this water washing operation three times,
By distilling off toluene from the organic layer and drying under reduced pressure, PTMG with a number average molecular weight of 2,750 is obtained as a canned product of 62.
9g was obtained.

[0052]

[Effects of the Invention] By the method of the present invention, polyoxytetramethylene glycol can be produced efficiently in high yield by using a solid super acid catalyst that is easy to recover and recycle and is cheaper than conventional ones as a polymerization catalyst. It became possible.

Claims (1)

[Claims] [Claim] General formula: MxOy (x, y are 1 to 3
composite metal oxide selected from the group of metal oxides represented by
A method for producing polyoxytetramethylene glycol, which comprises polymerizing tetrahydrofuran in the presence of a solid superacid catalyst consisting of.