CS277263B6 - Process for preparing methyl succinic anhydride - Google Patents

Abstract

Method for production of methylsuccinic anhydride by catalytic hydrogenation of itaconic acid. The process is characterized by the use of a Pd catalyst on carbon and acetic anhydride is used as a solvent. After filtering off the catalyst, the crude product is obtained after simple vacuum concentration. The solution concerns the production of intermediate products for the synthesis of drugs, polymers, resins and surfactants.

Description

The present invention relates to a process for the preparation of methylsuccinic anhydride (otherwise called pyruvic anhydride or dihydro-3-methyl-2,5-furandione) of formula I by catalytic hydrogenation of itaconic acid of formula II.

ch ₂ = c -ccca

Cg., - C0C (II)

Methylsuccinic, itaconic and their anhydrides are known substances.

One of the most important ways to prepare methylsuccinic acid (and its anhydride) is the reduction of itaconic acid, especially catalytic reduction. In the older literature (J. Russ. Phys. Chem. Soc. 62 1975 (1930), CA 26 16 ⁷ ) there is a mention of the use of Pt black in the ether environment. The use of PtO ₂ under a hydrogen pressure of 50 lb. was described, hydrogenated in 85% ethanol and in water (J. Am. Chem. Soc. 74 3933; 82 4389).

Raney nickel catalyst was used for the synthesis of methylsuccinic acid and its salts in the hydrogenation of itaconic acid. Pressure hydrogenation in water has been described (J. Chem. Soc. 1949 2139) or in the form of the sodium salt (U.S. Pat. No. 2,773,897; Org. Synth. 34 74 (1954)). Reduction with hydrazine at 90 ° C has also been described (USSR 449 906).

A high-quality Raney nickel catalyst was obtained using the (Mo) promoters (Chem. Ind. (Dekker) 1981, 5, 383).

In the USSR, the kinetics of model reactions on Raney nickel in ethanol and on Pd with CaCO ₃ or BaSO ₄ support were studied (Tr. Inst. Khim. Nauk Akad. Nauk Kaz. SSR 17 32 (1967); 1968 (22) 32).

The hydrogenation of itaconic acid by means of a cyanocobalt complex has also been described (U.S. Pat. No. 3,185,727; J. Am. Chem. Soc. 90 (7) 1914 (1968)).

A process for the preparation of anhydride from methylsuccinic acid is known. In particular, excess acetic anhydride is used, the reaction mixture is heated under reflux for several hours and the pure product is obtained after evaporation of the acetic anhydride by vacuum distillation (J. Am. Chem. Soc. 67 1645 (1945)). Similarly, acid anhydrides can be prepared catalyzed by metal salts, for example at 70 [deg.] C. in an acetic anhydride medium for 1 hour (DE 3 644 222).

CS 277263 B6 2

The described processes by hydrogenation of itaconic acid followed by anhydridization of methylsuccinic acid have a number of disadvantages. The use of expensive Pt-based catalysts in an aqueous or aqueous-alcoholic environment presupposes the isolation of methylsuccinic acid and the subsequent work-up to the anhydride. When Raney nickel is used, it is hydrogenated in an aqueous medium, methyl succinic acid must be laboriously isolated from the sodium salt, and salt wastes are generated. The use of a Pd / CaCO ₃ catalyst also presupposes the need to isolate methylsuccinic acid; for Pd to BaSO ₄ , Pd regeneration can be complicated.

The process according to the invention eliminates said disadvantages by hydrogenating itaconic acid in an acetic anhydride medium in the presence of. Pd catalyst on activated carbon. After filtering off the catalyst and evaporating the excess acetic anhydride, the crude methyl succinic anhydride is obtained directly, which can be purified by known methods, for example by vacuum distillation.

Surprisingly, the production of anhydride can be simplified, and the isolation of methylsuccinic acid associated with losses and waste generation is not necessary. The hydrogenation uses a conventional Pd / C catalyst, where Pd regenerations are worked out.

The process according to the invention is characterized in that the concentration of itaconic acid in acetic anhydride is in the range of 10 to 40% by weight, preferably around 25% by weight, hydrogenated under hydrogen pressures of 0.1 to 6 MPa, preferably 0.3 to 0%. .5 MPa, at temperatures of 10 to; 90 DEG C. The specific consumption of Pd / C catalyst, based on the product, is 0.03 to 10% by weight, with a Pd content in the catalyst of 1 to 10% by weight, the hydrogenation lasting 0.5 to 7 hours, depending on the conditions.

After filtering off the catalyst, acetic anhydride (containing acetic acid) is distilled off under vacuum at a pressure of 5 to 20 kPa and at temperatures of up to 90 ° C in 1 to 3 hours. The crude product, containing mainly acetic anhydride from impurities, may be subjected to further distillation (0.06 kPa, 80 ° C) to obtain pure, colorless methylsuccinic anhydride.

The process according to the invention is technologically and economically efficient, laborious and ecological.

Further details of the process according to the invention follow from the following examples, which merely illustrate but do not limit the process.

Example 1

In a laboratory autoclave, 26 g of itaconic acid in 100 ml of acetic anhydride were hydrogenated at room temperature under a hydrogen pressure of 3 to 5 MPa for 1 h, using 1.3 g of Pd / C catalyst (5% Pd). ₍

After filtering off the catalyst, it was concentrated under a water pump vacuum, at bath temperatures of 80 DEG C. for 1 hour. 20.5 g of crude product with a methyl succinic anhydride (GLC) content of 95% by weight were obtained. %.

Example 2

3 kg of itaconic acid, 8 It of acetic anhydride and 0.2 kg of Pd / C catalyst (50% by weight, water, 3% Pd on dry matter) were charged to a 20 It autoclave. It was hydrogenated under a hydrogen overpressure of 0.1 to 0.5 MPa (make-up) for 3 h at a temperature of 20 to 60 ° C. After filtering off the catalyst, the filtrate was concentrated for 2 h under a water ring vacuum at temperatures up to 90 ° C.

3.1 kg of crude product were obtained, with a methyl succinic anhydride content of 74% by weight, i.e. a yield of 87% by weight.

Claims (1)

PATENT CLAIMS Process for the preparation of methylsuccinic anhydride of formula I CH 2 -CH -CO ³ I / 0 ^(I) QH.-CO by catalytic hydrogenation of itaconic acid, characterized in that Pd on carbon is used as catalyst in an amount of 0.03 to 10% by weight, based on the product, with a Pd content in the catalyst of 1 to 10% by weight, it uses acetic anhydride as solvent, the initial concentration of itaconic acid in it is 10 to. 40% by weight, preferably about 25% by weight; it is hydrogenated under hydrogen pressures of 0.1 to 6 MPa, preferably 0.1 to 0.5 MPa, at temperatures of 10 to 90 ° C for 0.5 to 7 hours; after filtering off the catalyst, the solvent is evaporated off under vacuum at temperatures up to 90 ° C for 1 to 3 h.