Accession Number : AD0700606

Title :   RECTIFICATION-SUBLIMATION OF PYROMELLITIC DIANHYDRIDE,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Mazitov,M. F. ; Mukhutdinov,R. Kh. ; Borshchenko,V. P. ; Anashkin,N. P.

Report Date : 08 OCT 1969

Pagination or Media Count : 9

Abstract : Pyromellitic dianhydride (PMDA) 1,2,4,5-benzetetracarboxylic 1,2:4,5-dianhydride, used in the synthesis of polyimides, is usually purified by recrystallization or fractional distillation-sublimation, using mineral oil as a third component. The authors ascertained the feasibility of purifying PMDA by rectification-sublimation, excluding the third component. Vacuum rectification with subsequent sublimation of the PMDA was used. Installation consisted of a vat, still, and U-shaped dephlegmator connected to a condensor and receptacle. Temperature and pressure were selected, using the dependence of the vapor pressure of PMDA on temperature. Without the third component, the distilled PMDA from the durol crude source product by the given method, was 99.2-99.6% pure, but the yield was only 45-50% of the potential. (Author)

Descriptors :   (*ANHYDRIDES, PURIFICATION), DISTILLATION, SUBLIMATION, USSR

Subject Categories : Industrial Chemistry and Chemical Processing
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE