JP3191456B2 - Method for producing carboxylic acid monoanhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing monoanhydride of 1,2,3,4-butanetetracarboxylic acid (hereinafter abbreviated as "BTC"). BTC monoanhydride is useful as a resin modifier and a function-imparting agent in addition to being able to obtain various derivatives because its anhydride group is active.

[0002]

2. Description of the Prior Art As a method for producing BTC monoanhydride, B
A method is known in which TC (meso form) is heated to the melting point (189 ° C.) or is heated and dehydrated in nitrobenzene at 180 to 190 ° C. (Asahi Glass Industrial Technology Promotion Association, Vol. 11, p. 374, 1965). . However, with these methods,
Since BTC needs to be heated to a temperature close to its melting point, a large amount of heat is required, and furthermore, there is a problem that the product is colored and the raw materials are deteriorated, which is not practical.

The present inventors have previously proposed a method of heating and dehydrating under reduced pressure at a temperature not higher than the melting point of the solution as a method for solving such a problem (Japanese Patent Laid-Open No. 63-159377).
issue).

[0004]

SUMMARY OF THE INVENTION The present invention provides a novel and useful method for producing BTC monoanhydride of good color and high purity under industrially advantageous conditions with high selectivity and high yield. The purpose is to do.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and have found that BTC is heated and dehydrated in a nonpolar solvent in the presence of a tertiary amine having a specific structure. As a result, it has been found that anhydrous can be dehydrated at a low temperature and a predetermined effect can be obtained, and the present invention has been completed based on such findings.

That is, the process for producing BTC monoanhydride according to the present invention comprises the steps of:
A method for producing a monoanhydride, wherein the dehydration is carried out by heating in the presence of one or more tertiary amines represented by the general formula (1), (2) or (3). And

[0007]

Embedded image [Wherein R ¹ , R ² and R ³ are the same or different and each have 1 carbon atom.
To 40 alkyl groups, alkenyl groups, cyclohexyl groups optionally having an alkyl group, and phenyl groups optionally having an alkyl group. However, the total number of carbon atoms of R ¹ , R ² and R ³ is ³ to 80, preferably 7 to 60. ]

[0008]

Embedded image

Wherein R ⁴ represents an alkyl group having 1 to 30 carbon atoms
Represent. ]

[0009]

Embedded image [In the formula, R ⁵ represents an alkyl group having 1 to 30 carbon atoms. ]

As the BTC used in the present invention, either a wet crystal product or a dry product is possible, but a wet product that does not require a drying step in the previous stage is advantageous in operation. The moisture content of the wet product is not particularly limited. However, if the moisture content is too large, a large amount of time and heat is required for heating and dehydrating. Therefore, the moisture content is 50 wt. %, Preferably about 20% by weight.

As the tertiary amine represented by the general formula (1), specifically, trimethylamine, triethylamine,
Dimethylbutylamine, dimethylhexylamine, dimethyloctylamine, dimethyldecylamine, dimethyldodecylamine, dimethyltetradecylamine, dimethylhexadecylamine, dimethyloctadecylamine,
Dimethyl octadecenylamine, diethylhexylamine, dioctylmethylamine, didecylmethylamine,
Aliphatic tertiary amines such as didodecylmethylamine, ditetradecylmethylamine, dihexadecylmethylamine, dioctadecylmethylamine,

Alicyclic tertiary amines such as dimethylcyclohexylamine and methyldicyclohexylamine;

N, N-dimethylaniline, N, N-diethylaniline, N, N-dimethyl-p-toluidine,
Aromatic tertiary amines such as N, N-dimethyl-2,4-dimethylaniline are exemplified.

As the heterocyclic tertiary amine represented by the general formula (2), specifically, 4-ethylpyridine, 4-dimethylaminopyridine, 4-decylpyridine, 4-dodecylpyridine, 4-tetradecyl Examples thereof include pyridine, 4-hexadecylpyridine, 4-octadecylpyridine and the like.

As the heterocyclic tertiary amine represented by the general formula (3), specifically, N-decylpiperidine, N-dodecylpiperidine, N-tetradecylpiperidine, N-
Hexadecylpiperidine, N-octadecylpiperidine and the like are exemplified.

The use amount of the tertiary amine is preferably 0.001 to 50% by weight, particularly preferably 0.1 to 20% by weight, based on BTC. When the addition amount of the tertiary amine is less than 0.001% by weight, the reaction rate is low. On the contrary, when the addition amount exceeds 50% by weight, no remarkable effect is recognized, and it is economically disadvantageous. Absent.

The non-polar solvent according to the present invention is preferably
Any solvent may be used as long as it is a nonpolar solvent having a boiling point range of 00 to 200 ° C. and capable of azeotropically distilling off generated water. For example, hydrocarbons such as toluene, xylene, ethylbenzene, cumene, hexane, octane, decane, cyclohexane, methylcyclohexane, ethylcyclohexane, decalin, tetralin, and light oil; Hydrogen is exemplified, and among them, toluene, xylene, decalin, octane, chlorobenzene and the like are recommended. These are used alone or in a mixture of two or more.

When a polar solvent, for example, an aprotic polar solvent such as N, N-dimethylformamide or diglyme is used, the amount of the product dissolved in the solvent increases and the yield decreases, which is not preferable.

The amount of the nonpolar solvent to be used is not particularly limited as long as stirring in the reaction system is possible, but usually, the BTC concentration is preferably about 5 to 80% by weight, and particularly preferably about 10 to 50% by weight. You. If the BTC concentration is less than 5% by weight, the productivity is reduced and the practicality is lacking. If the BTC concentration exceeds 80% by weight, it is difficult to sufficiently remove generated water due to a decrease in the amount of reflux, and the reaction product is blocked. In any case, it is not preferable.

The thermal dehydration (anhydration) reaction in the present invention is carried out by mixing BTC and a tertiary amine in a nonpolar solvent at 70 to 18%.
It heats and stirs at about 0 degreeC, preferably about 80-150 degreeC, and performs by performing azeotropic dehydration of the produced water.

The reaction is conveniently carried out at normal pressure, but may be carried out under reduced or increased pressure as long as the reaction temperature satisfies the above conditions.

The reaction is usually completed in 0.1 to 10 hours.

When the reaction is carried out under the above conditions, the reaction mother liquor containing BTC monoanhydride and the tertiary amine can be easily separated by filtration or the like. The crystals separated by filtration are washed with a suitable solvent, for example, acetone, methyl ethyl ketone, dioxane, tetrahydrofuran, diethyl ether, diglyme, methanol, and the like, and then dried to obtain a highly purified target product with high selectivity.

The recovered reaction mother liquor can be used for the dehydration reaction repeatedly without any treatment.

[0025]

The present invention will be described in detail below with reference to examples and comparative examples. Example 1 50 equipped with a cooling pipe with a water separator, a thermometer and a stirrer
46.8 g of dried BTC product in a 0 ml four-necked flask
(0.2 mol), xylene (200 g) and N, N-dimethyldodecylamine (4.0 g) were charged, and the mixture was dehydrated at a reaction temperature of 135 ° C. for 1.5 hours while distilling off generated water. After completion of the reaction, the mixture was cooled to 30 ° C., and the crystals were separated by filtration.
0 g and dried to give white BTC monoanhydride 40.0
g was obtained.

This product has a melting point of 234.8 ° C. (literature value 2).
32 ° C.), the total acid number was 1050 (theory 1048). Using the collected reaction mother liquor, a reaction was carried out in the same manner as at the beginning. As a result, the amount of BTC monoanhydride obtained was 42.
6g, melting point: 240.5 ° C, total acid value: 1058.

Example 2 A reaction was carried out for 1.5 hours in the same manner as in Example 1 except that 59.2 g of a BTC wet product (water content: 21%) was used as a raw material. After cooling, the BTC monoanhydride was filtered off and dried. The obtained BT
The amount of C monoanhydride was 40.2 g, the melting point was 233.3 ° C., and the total acid value was 1052.

Example 3 A reaction was carried out in the same manner as in Example 1 except that 0.5 g of dimethyldodecylamine was used as a tertiary amine. As a result, 40.6 g of BTC monoanhydride was obtained, and the melting point was 246.5 ° C. and the total acid value was 1055.

Example 4 Dimethylcyclohexylamine 1.0 as tertiary amine
The reaction was carried out in the same manner as in Example 1 except that g was applied. As a result, 40.6 g of BTC monoanhydride was obtained, and the melting point was 245.0 ° C. and the total acid value was 1057.

Example 5 A reaction was carried out in the same manner as in Example 1 except that 2.0 g of N, N-dimethylaniline was used as a tertiary amine. The result was 40.4 g of BTC monoanhydride, which had a melting point of 245.7 ° C. and a total acid number of 1046.

Example 6 A reaction was carried out in the same manner as in Example 1 except that 1.0 g of 4-ethylpyridine was used as a tertiary amine. As a result, 4
0.0 g of BTC monoanhydride was obtained, having a melting point of 239.8 ° C. and a total acid number of 1060.

Example 7 A reaction was carried out in the same manner as in Example 1 except that 1.5 g of N-dodecylpiperidine was used as a tertiary amine. As a result, 40.2 g of BTC monoanhydride was obtained, which had a melting point of 244.6 ° C. and a total acid value of 1061.

Example 8 A reaction was carried out in the same manner as in Example 1 except that 250 g of octane was used as a non-polar solvent. As a result, 40.0 g of B
TC monoanhydride was obtained, which had a melting point of 240.8.
° C, the total acid number was 1063.

Example 9 150 g of decalin and 25 g of toluene as nonpolar solvents
The reaction was carried out in the same manner as in Example 1 except for using. As a result, 39.6 g of BTC monoanhydride was obtained, and the melting point was 245.9 ° C. and the total acid value was 1066.

Example 10 The reaction was carried out in the same manner as in Example 1 except that 250 g of chlorobenzene was used as the non-polar solvent. As a result, 40.5
g of BTC monoanhydride is obtained, the melting point of which is 24.
At 6.6 ° C., the total acid value was 1059.

Comparative Example 1 The reaction was carried out for 5 hours under the same conditions as in Example 1 except that N, N-dimethyldodecylamine was not used, but no water was generated. After cooling, the crystals (4) obtained by filtration and drying were obtained.
6.5 g), the melting point was 190.5.
° C, the total acid value was 955, and the crystal was recognized as BTC as a raw material.

[0037]

By applying the method according to the present invention, high-purity BTC monoanhydride with little alteration and coloration upon heating can be obtained with high selectivity and high yield.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07D 307/60 B01J 31/02 102 C07B 61/00 300 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A method for producing 1,2,3,4-butanetetracarboxylic monoanhydride by heating and dehydrating 1,2,3,4-butanetetracarboxylic acid in a nonpolar solvent,
1, 2, 3, 4 characterized by being dehydrated by heating in the presence of one or more tertiary amines represented by the general formula (1), (2) or (3). -A method for producing butanetetracarboxylic acid monoanhydride. Embedded image [In the formula, R ¹ , R ² , and R ³ are the same or different and each have an alkyl group having 1 to 40 carbon atoms, an alkenyl group, a cyclohexyl group optionally having an alkyl group, or an alkyl group having an alkyl group. Represents a good phenyl group. However, R ¹ , R ² , R ³
Has a total carbon number of 3 to 80. ] [In the formula, R ⁴ represents an alkyl group having 1 to 30 carbon atoms. ] [In the formula, R ⁵ represents an alkyl group having 1 to 30 carbon atoms. ]