SU433128A1 - - Google Patents

Description

The invention relates to the preparation of alkali carbonate dianhydride of carbonic acid of various configurations, which find a variety of applications for the polymer industry. For example, production of heat-resistant materials.

IzEsten is a method of producing 1-cis-, 2-cis-, 3-cis-, 4cis-cyclopentantetracarbonoic acid dianhydride by acid by dehydrotation of the corresponding acid under acetic anhydride, taking E with excess, while heating not at the same time as the reaction mixture. However, the process of formation of the dianhydride is accompanied by side reactions of the transformation of the original and the target product, and, due to this, contamination of the target product with a dark colored impurity occurs. The latter is difficult to separate, and therefore the preparation of a pure product is complicated.

The purpose of the invention: - improving the quality of the whole product. For this, the process is driven in an aromatic hydrocarbon medium, for example toluene.

The process is expedient to carry out at a molar ratio of the starting acid and acetic anhydride, at a ratio of 1: 3.5-7.0. In addition, xylene or pseudocumene can be used as an aromatic solvent.

The dehydration is carried out at 110140 ° C, after it is finished, the acetic acid formed is distilled off and the unreacted acetic anhydride and the initial solvent are regenerated, which are then recycled to the process.

Example. In the two-necked

a flask equipped with a mechanical valve and reflux condenser,

25 g (0.102 mol) of the starting acid are placed, 60 ml are added to it

(0.81 mol) of acetic anhydride and 60 ml of xylene isomers. With continuous stirring, the solution is boiled for 3 hours. further cooled, filtered, washed with 5 ml, the precipitate E is dried under vacuum at ilOOOc (dry air is passed) and 20.6 target dianhvangdrid is obtained i t, pl. 2220С..Output of the target pro; duct 96.7 ..

PRI mme R 2. The process is carried out; analogously to Example I. To 12.5 g (0.51 mol) of the acid output is 25 ml (3.4 mol) of acetic acid; hydride and 15 ml of pseudocumene and are heated to 140 ° for

hour. 10.54 g of dinghidri are obtained (lMSCHEZT of the INVENTION

The method of producing dianhydride, cycled danethane 2 caraonic acid by means of dilution with acid using acetic anhydride at a temperature not higher than the boiling point of the reaction mixture, followed by extraction of the target product by means of an effective curacy, by using, using a non-working flow, using a cipher body, using a non-stick binder, using a non-toxic mixture of acetic anhydride acid). such as toluene.