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:
Jan. 06, 1998
Filed:
Feb. 16, 1996
Giuseppe Prota, Naples, IT;
Gottfried Wenke, Woodbridge, CT (US);
Leszek Wolfram, Stamford, CT (US);
Clairol Incorporated, New York, NY (US);
Abstract
The present invention is directed to the preparation of an aqueous hair dyeing composition containing an effective hair dyeing amount--at least 2 mg/ml--5,6-dihydroxyindole (DHI). An aqueous hair dyeing composition is produced by reacting under essentially anaerobic conditions dopa or a salt thereof with an alkali metal ferricyanide oxidant in an aqueous reaction medium to obtain dopachrome, and permitting the dopachrome to undergo rearrangement in the aqueous medium to form 5,6-dihydroxyindole, said rearrangement being conducted in the substantial absence of oxidant, the aqueous medium being buffered by sufficient buffering agent to maintain a pH of from about 4.5 to about 9 for the reaction medium throughout the series of reactions that take place thereafter, removing the ferrocyanide species present in the aqueous system, and lastly, charging the composition into a suitable container.