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:
Jan. 14, 1992
Filed:
Oct. 06, 1989
Applicant:
Inventors:
Mengxian Ding, Changchun, CN;
Zugiang Wang, Changchun, CN;
Zhenghua Yang, Changchun, CN;
Jing Zhang, Changchun, CN;
Assignee:
Changchun Institute of Applied Chemistry, Changchun, CN;
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C07C / ;
U.S. Cl.
CPC ...
560 96 ; 560 76 ; 562488 ;
Abstract
Biphenyl tetracarboxlic acid esters and derivatives thereof are prepared by the coupling reaction of 4-halogen substituted o-benzenedicarboxylic acid ester, carried out in an aprotic polar solvent in the presence of a pre-prepared triphenylphosphine-nickel chloride or trialkylphosphine-nickel chloride catalyst, zinc powder as the reducing agent, and an alkali metal halide promoting agent. The ester may be hydrolyzed in basic solution to afford the corresponding acid. The acid may be heated or boiled with acetic anhydride to afford the biphenyl dianhydride.