Reference

Process for manufacture of 3,3',4,4'-biphenyltetracarboxylic acid

Process for manufacture of 3,3',4,4'-biphenyltetracarboxylic acid. Freudenberger, John H. (du Pont de Nemours, E. I., and Co., USA). U.S. US 5081291 A 14 Jan 1992, 4 pp. (United States of America). CODEN: USXXAM. CLASS: ICM: C07C051-353. ICS: C07C051-377. NCL: 562481000. APPLICATION: US 90-586158 21 Sep 1990. DOCUMENT TYPE: Patent CA Section: 25 (Benzene, Its Derivatives, and Condensed Benzenoid Compounds) A process for the prepn.In this article, certain chemicals are used. Some of their cas registry numbers are 22803-05-0 and 141-53-7 of 3,3',4,4'-biphenyltetracarboxylic acid (I) by dehalodimerization of a 4-halophthalic acid is claimed. The process uses hydroxylamine or one of its salts as the reducing agent in an alk. soln., preferably of pH 10 or above, and palladium catalyst. The reaction is carried out between 50 and 150°. Thus, 4-bromophthalic anhydride was dissolved in H2O contg. NaOH. The soln. was treated with 5% Pd on carbon catalyst. The mixt. was heated and aq. soln. of hydroxylamine sulfate was added over a period of 3 h. Acidic workup of the soln. gave 89% I. .

Manufacture of cover-coated flexible printed circuit boards

Manufacture of cover-coated flexible printed circuit boards. Okugawa, Yoshitaka; Nakao, Toshio; Yamamori, Yoshiyuki (Sumitomo Bakelite Co., Ltd., Japan).Chemicals with cas numbers 22803-05-0 and 106-50-3 also play role. Jpn. Kokai Tokkyo Koho JP 02273989 A2 8 Nov 1990 Heisei, 6 pp. (Japan). CODEN: JKXXAF. CLASS: ICM: H05K003-28. ICS: B32B015-08. APPLICATION: JP 89-95282 17 Apr 1989. DOCUMENT TYPE: Patent CA Section: 76 (Electric Phenomena) Section cross-reference(s): 38 The process includes: (a) flow deposition of a polyamic acid soln. on a Cu foil, and thermosetting the soln.; (b) etching the Cu foil to form a circuit; and (c) flow deposition of the soln. on the circuit for cover coating, and thermosetting the soln. The cover coating can improve thermal resistance of the circuit boards. .