Process for preparing bis(ether anhydrides)

摘要

A process for making bis(ether anhydrides) employs alkylamines having low melting temperatures thus allowing for novel intermediate process steps for preparing bis(ether anhydrides). The alkylamines have alkyl groups which contain at least three carbon atoms and have boiling temperatures in the range of 48 to 250 DEG C at atmospheric pressure. As a result of using these amines, liquid alkylamines now can be employed in the imidization process step. The N-alkyl nitrophthalimides prepared from the recovered imidization product according to this invention can now be purified using liquid/liquid extraction or vacuum distillation. The alkyl nitrophthalimides prepared according to this invention provide for displacement reactions which now can be run at a high solids level. Likewise, the exchange reaction can be run at a higher solids level, and thus achieves an efficiency level which is higher than conventional processes.