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:
Oct. 12, 1999
Filed:
Nov. 04, 1997
Harold S Freeman, Raleigh, NC (US);
David Hinks, Spartanburg, SC (US);
Jolanta Sokolowska-Gajda, Raleigh, NC (US);
North Carolina State University, Raleigh, NC (US);
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.