RECTIFICATION-SUBLIMATION OF PYROMELLITIC DIANHYDRIDE,

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)

Document Details

Document Type
Technical Report
Publication Date
Oct 08, 1969
Accession Number
AD0700606

Entities

People

  • M. F. Mazitov
  • N. P. Anashkin
  • R. Kh. Mukhutdinov
  • V. P. Borshchenko

Organizations

  • National Air and Space Intelligence Center

Tags

DTIC Thesaurus Topics

  • Critical Temperature
  • Distillation
  • Fluids
  • Glass Transition Temperature
  • Isothermal Processes
  • Partial Pressure
  • Phase Transformations
  • Recrystallization
  • Sublimation
  • Transition Temperature
  • Vapor Pressure
  • Vapors

Readers

  • Electrical Engineering
  • Materials Science and Engineering.
  • Polymer Science and Engineering.