RU681757C - Method of producing methyl exhers of aliphatic dicarboxylic acids - Google Patents

Description

The invention relates to the field of chemical technology, and more particularly to a process for the preparation of methyl esters of aliphatic acids C2-Ci2. used in the production of dicarboxylic acids.

The purpose of the invention is to simplify the process.

For this, the dicarboxylic acid dimethyl ester is reacted with Ci-C3 monocarboxylic acid, while the resulting monoester is withdrawn from the reaction zone at the ratio of dicarboxylic acid dimethyl ester: monocarboxylic acid: water 0.71000: 0 .7-1000: 0.7-77 the presence of

acid catalyst, mainly mineral acid or KU2x8 cation exchanger in N form at a temperature of 60-110 ° C. Before the isolation of the desired product by distillation, the reaction products are extracted with a chlorine-containing organic solvent, usually carbon tetrachloride, trichlorethylene or tetrachlorethylene. As cation exchange resin, a styrene butadiene ion exchange resin with a sulfo group in the H form is used.

The method is based on the transesterification reaction of dialkyl esters of dicarboxylic acids with monocarboxylic

acids in the presence of acid catalysts, which can be used mineral acids or ion exchange resins in the H form.

The dicarboxylic acid dialkyl ester is reacted with a strictly equimolar amount of monocarboxylic acid at atmospheric pressure and temperatures up to 100 ° C. Excess monocarboxylic acid is undesirable, as it contributes to the destruction of the resulting monoalkyl ester of dicarboxylic acid to form free dicarboxylic acid.

The resulting monocarboxylic acid alkyl ester is continuously withdrawn from the reaction zone by distillation, which contributes to a shift in the equilibrium towards the desired product.

In the proposed method for producing monoalkyl esters, the dicarboxylic acid dialkyl ester and monocarboxylic acid obtained as waste material are returned to the reaction zone for the transesterification of dialkyl esters of dicarboxylic acids with monocarboxylic acids, and the monocarboxylic ester is used as a commercial product.

Thus, the proposed method can be implemented in the form of a closed cycle and allows you to get monoalkyl ethers without the formation of effluents, unused waste and gas emissions.

PRI me R 1. In a reaction flask equipped with a reflux condenser, placed 23.6 g of dimethyl ester of acid oxalis, 24 acetic acid (98% of the basic substance), 10.0 g of water (45% by weight of monocarboxylic acid) and 1.08 g of 57% nitric acid. The mixture was kept at for 2 hours. After distillation under reflux, the water temperature of which was maintained at 58 ° C with a thermostat, 15.0 g of methyl acetate was condensed (boiling point 57,). The reaction mass is treated with trichlorethylene.

The resulting reaction mixture contains, g: dimethyl oxalate 12.41; monomethyl oxalate 8.68; oxalic acid 2.69.

The yield of monomethyl oxalate from theory after distillation is 88.0%.

Example 2. In a reaction flask with a reflux condenser, 16.0 g of glutaric acid dimethyl ether, 4.6 g of formic acid (analytical grade 99.7% of the basic substance), 2.2 g of water (52.8% by weight) were placed carboxylic acid) and 0.4 g of 57% nitric acid.

The mixture was kept at 98-100 ° C and then .. limo 9 c. After distillation with a condenser, the water temperature was maintained at 33 ° C using a thermostat, 5.5 g of methyl formate was condensed (boiling point 32 ° C).

The resulting reaction mixture contains, g: dimethyl glutarate 2.189; monomethyl glutarate 7.226; glutaric acid 4.865.

The reaction mixture is treated with trichlorethylene 1: 3, the extract is cooled

0 to 0 ° C. The precipitated glutaric acid was filtered, washed with a cold solvent, and the filtrate was combined with the bulk of the extract.

Evaporate the solvent in a water bath to 1/3 volume. Cool again to 0 ° C. A small amount of glutaric acid is also precipitated. It is filtered. The filtrate contains 2.189 g of dimethyl glutarate, 6.866 g of monomethyl glutarate, traces of glutaric

0 acid. The solvent was distilled off from the mixture in a water bath, then under vacuum at 84-85 ° C at 6 mm Hg. a fraction of dimethyl glutarate 2.19 g was distilled off. The bottom residue contained 6.866 g of monomethyl glutarate with a purity of 99.6%, 0.027 g of glutaric acid;

Yield of monomethyl glutarate after isolation of 95% of theory.

PRI me R 3. In a reaction flask equipped with a reflux condenser, 14.6 g of succinic acid dimethyl ether, 14.8 g of propionic acid (h, 98% of the basic substance), 4.0 g of water (30, 6% by weight of carboxylic acid) and 0.4 g of 57% nitric acid.

5 The mixture was kept at 106 ° С for 1 h. After distillation under reflux, the temperature of which was maintained at 80 ° С, 8.5 g of methylpropionate were condensed (boiling point

0 79,).

The resulting reaction mixture contains, g; succinic acid dimethyl ester 3.495; succinic acid monomethyl ester 7.177; succinic acid 2.619.

5 The reaction mixture is treated with tetrachlorethylene 1: 3. The extract was cooled to 0 ° C. The precipitated succinic acid was filtered, washed with a cold solvent, and the filtrate was combined with the basic one.

0 mass of extract.

Evaporate the solvent in a water bath to 1/3 volume. Cool again to 0 ° C. A further small amount of succinic acid is precipitated. It is filtered. The filtrate contains, g: succinic acid dimethyl ether 3,495; succinic acid monomethyl ester 9.961; succinic acid 0.04.

The solvent was distilled off in a water bath. Then, under vacuum, 11 mmHg succinic acid dimethyl ester is distilled off at 8 ° C and in the cube there remains 6.961 g of succinic acid monomethyl ester with a purity of 99.4%, succinic acid 0.04 g.

The yield of succinic acid monomethyl ester is 97.0% by weight after isolation.

PRI me R 4. In a reaction flask, as described in example 1, was placed 17.4 g of adipic acid dimethyl ester, 6.0 g of acetic acid (h, 98% of the basic substance) and 0.1 g of concentrated (95 , 6% basic in) sulfuric acid. The mixture was kept at a temperature for 1 hour. After distillation under reflux, at a temperature of 58 ° C, 7.8 g of methyl acetate were condensed (boiling point 57.1 ° C).

The resulting reaction mixture contains, g: dimethyl adipate 6.754; monomethyl adipate 9.083; adipic acid 0.677.

Adipino monomethyl ether yield. total acid is 92.8% of theory.

PRI me R 5. In a reaction flask, as described in example 1, was placed 2.3 g of dimethyl ester of sebacic acid, 1.2 g of acetic acid and 0.9 g of concentrated nitric acid. The mixture is kept at a temperature of 60 ° C for 1 h20 min. After distillation under reflux,; at a temperature of 58 ° C, 0.7 g of methyl acetate was condensed (boiling point 57.1 ° C).

The resulting reaction mixture contains, g: unreacted dimethylsebacinate 0.426; monomethylsebacinate 1.287; .sebacic acid 0.228.

The yield of sebacic acid monomethyl ester is 71% of theoretical.

The reaction mixture is treated with carbon tetrachloride. The organic filtrate contains, g: sebacic acid dimethyl ester 0.426; sebacic acid monomethyl ester 1.197; sebacic acid - traces (not more than 0.02).

The solvent is distilled off in a water bath, and then under a vacuum of 15 mmHg. at a temperature of 165-167 ° C, a fraction of sebacic acid dimethyl ester is distilled off. Monomethyl sebacinate 1.197 remained in the cube. g purity 98.3%; sebacic acid 0.02 g.

The yield after isolation of sebacic acid monomethyl 5 ether was 93%.

Example 6. In a reaction flask equipped with a reflux condenser and a mechanical stirrer, 17.4 g of adipic acid dimethyl ether are placed,

0 6.0 g of acetic acid (h, concentration 98%), 6.0 g of KU-2 cation exchanger in the H form. Humidity of cation exchanger 50%. The mixture is heated to 85 ° C. with stirring for 90 minutes. The reaction mixture contains

5 P dimethyl adipate 7.463; monomethyl adipate 6.544; adipic acid 2.362. The yield of adipic acid monomethyl ester is 71.62% of theory.

Example 7. In a reaction flask equipped with a reflux condenser, 2.58 g of dimethyl ether was placed. 1.10 decanedicarboxylic acid, 6.0 g of acetic acid (h, the basic substance content is 98.0 wt.%), 0.57 g of 57% nitric acid and 5.0 g of water. The mixture is heated to 95 ° C and incubated for 45 minutes at a temperature not exceeding 100 ° C. After the reflux condenser, the temperature of which is maintained at 58 ° C, 6.1 g of methyl acetate are condensed (boiling point 57.1 ° C). The resulting reaction mixture contains, g: unreacted dimethyl ether 0.458; mo.nomethyl ether 1,420; 1.10 decandy 5 kap6oHOBaq acid 0.252. The reaction mixture is treated with carbon tetrachloride as described in Example 1. The organic layer contains, g: dimethyl ether O, 458: monomethyl ether 1,, 10

0 decanedicarboxylic acid 0.252.

The reaction mixture is treated with carbon tetrachloride as described in Example 1. The organic layer contains, g: dimethyl ether 0.458; monomethyl 5 ophir 1,420; 1.10 decandicarboxylic acid - traces (not more than 0.01 g). The yield of 1,10 decanedicarboxylic acid monoester is 71.0% of theory.

The conditions for the examples are given in table.

0 1 and 2.

Ta 6l and tsa 1

Y a b l i c a 2