The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 01, 1994
Filed:
Aug. 11, 1992
Ranjit K Roy, Baton Rouge, LA (US);
Ali M Dadgar, Baton Rouge, LA (US);
Donald O Hutchinson, Baton Rouge, LA (US);
Keith G Anderson, Baton Rouge, LA (US);
Ethyl Corporation, Richmond, VA (US);
Abstract
This invention relates to a process for preparing a white bisimide product which principally contains N,N'-alkylene-bis(tetrabromophthalimide) or N,N'-bis(tetrabromophthalimide). The process features: providing, in a reaction vessel, a solution containing tetrabromophthalic anhydride and a solvent which contains at least about 15 weight percent of a mono-, di- or tri- carboxylic acid having a dissociation constant not higher than 1.0.times.10.sup.-3 at 25.degree. C.; forming a reaction mass by adding to the solution a diamine or a diamine salt formed by the partial or total diamine neutralization of a mono-, di- or tri- carboxylic acid having a dissociation constant not higher than 1.0.times.10.sup.-3 at 25.degree. C., such formation of the reaction mass resulting in the production of a bisimide precipitate which becomes a constituent of the reaction mass; during the formation of the reaction mass, (i) retaining, in the reaction mass, at least a portion of the water produced during such formation, (ii) maintaining a substantially constant pressure in the reaction vessel, and (iii) not allowing the temperature of the reaction mass to reach a temperature below about 135.degree. C.; terminating the addition of the diamine or diamine salt when the molar ratio of the tetrabromophthalic anhydride initially present in the solution to the diamine or diamine salt added is from about 1.9:1 to about 2.1:1; and recovering, as the bisimide product, the bisimide precipitate.