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:
Feb. 05, 1980
Filed:
Mar. 03, 1978
Henry Bader, Newton Center, MA (US);
Michael H Feingold, Randolph, MA (US);
Polaroid Corporation, Cambridge, MA (US);
Abstract
In one embodiment, this application is directed to an improved method of synthesizing certain bis-pyrazolone oxonol compounds useful as antihalation dyes in photography which method comprises synthesizing a pyrazolone ethyl ester by reacting a p-N-alkylsulfonamidophenylhydrazine or its hydrochloride and sodium diethyl oxalacetate, hydrolyzing the pyrazolone ethyl ester thus formed to give the corresponding pyrazolonecarboxylic acid, esterifying the pyrazolonecarboxylic acid with a glycol to give the corresponding pyrazolone hydroxyalkyl ester and condensing said pyrazolone hydroxyalkyl ester with an aldehyde dianil hydrochloride to yield the dye product. In another embodiment, the p-N-alkylsulfonamidophenylhydrazine is prepared by reacting p-fluorobenzenesulfonyl chloride and a primary alkylamine to yield the corresponding 1-fluoro-4-N-p-alkylsulfonamidobenzene and then reacting said alkylsulfonamidobenzene with hydrazine hydrate to yield the corresponding p-N-alkylsulfonamidophenylhydrazine which may be converted to its hydrochloride salt by reaction with a solution of hydrochloric acid.