Organic pigments from twisted benzidines
US5965717A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 4, 1997 |
| Grant date | Oct 12, 1999 |
| Priority date | — |
| Expiry date | Nov 4, 2017 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B55/006
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Nonmutagenic, highly twisted derivatives of benzidine of the following formula ##STR1## useful as intermediates for the preparation of various organic pigments were obtained. The benzidine derivatives are significantly rotated about the biphenyl linkage due to bulky substituents at the R.sub.2 and/or R.sub.4 positions. Bisazomethine, disaoacetoacetanilide, disazopyrazolone, disazobenzimidazolone and disazonaphthol pigments prepared from these highly twisted benzidines exhibit hypsochromic spectral shifts relative to pigments prepared from other benzidine compounds with less twist about the biphenyl linkage, for instance, other benzidine compounds in which all four R.sub.2 and R.sub.4 represent H. Greenish-yellow, yellow, orange, red and brown pigments obtained from the twisted benzidines are nonmutagenic in the standard Ames test and Prival modification.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.