Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2006-03-18
2008-09-16
Puttlitz, Karl J (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S491000, C562S480000, C562S887000
Reexamination Certificate
active
07425650
ABSTRACT:
This invention relates to processes for preparing asymmetrical biphenyl tetracarboxylic acids and the corresponding asymmetrical dianhydrides, namely 2,3,3′,4′-biphenyl dianhydride (a-BPDA), 2,3,3′,4′-benzophenone dianhydride (a-BTDA) and 3,4′-methylenediphthalic anhydride (-MDPA). By cross-coupling reactions of reactive metal substituted o-xylenes or by cross-coupling o-xylene derivatives in the presence of catalysts, this invention specifically produces asymmetrical biphenyl intermediates that are subsequently oxidized or hydrolyzed and oxidized to provide asymmetric biphenyl tetracarboxylic acids in comparatively high yields. These asymmetrical biphenyl tetracarboxylic acids are subsequently converted to the corresponding asymmetrical dianhydrides without contamination by symmetrical biphenyl dianhydrides.
REFERENCES:
patent: 3940426 (1976-02-01), Itatani
patent: 4294976 (1981-10-01), Itatani
patent: 4958002 (1990-09-01), Imatani
patent: 5258530 (1993-11-01), Katsuro
patent: 2003/0088120 (2003-05-01), Yamamoto
patent: 343560 (1989-11-01), None
Polyhedron, 10(17), 2037-44; 1991.
Puttlitz Karl J
Stone Kent N.
The United States of America as represented by the Administrator
Tura James V.
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