Novel synthesis of bis pyrazolone oxonol dyes
US4187225A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 1978 |
| Grant date | Feb 5, 1980 |
| Priority date | — |
| Expiry date | Mar 3, 1998 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B23/02
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.