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:
Jun. 02, 1992
Filed:
Dec. 28, 1990
Applicant:
Inventors:
Martin Bartmann, Recklinghausen, DE;
Jurgen Finke, Marl, DE;
Wilfred Ribbing, Heesternweg, DE;
Gunter Poll, Marl, DE;
Assignee:
Huels Aktiengesellschaft, Marl, DE;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C07C / ; C07C / ; C07C / ;
U.S. Cl.
CPC ...
564430 ;
Abstract
High purity 4,4'-bis(4-aminophenoxy)diphenyl sulfone is prepared from p-aminophenol, alkali metal hydroxide and 4,4'-dihalodiphenyl sulfone by using a molar ratio of alkali metal hydroxide: 4-aminophenol in the range of 1.0-1.1:1.0 and a molar ratio of 4-aminophenol: 4,4'-dihalodiphenyl sulfone in the range of 2.005-2.05:1.0 and by using a dialkylamide or N-alkyl lactam as a solvent. Pristine products (no-recrystallization) of 99.0% purity having melting points above 195.degree. C. are obtained.