Process for making 2-aminomethyl-1, 4-diaminobenzene and its salts and compositions and methods for dyeing keratin fibers using same

US6461390B1 · kind B1 · utility

Assignee

• Wella GmbH · DE

Inventors

• Otto Goettel · Marly, CH
• Aline Pirrello · Givisiez, CH
• Andre Hayoz · Senèdes, CH

Key dates

• Filing date: Sep 22, 2000
• Grant date: Oct 8, 2002
• Expiry date: Jan 5, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C209/62
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

A process is described for making 2-aminomethyl-1,4-diaminobenzene, or a physiologically compatible salt of 2-aminomethyl-1,4-diaminobenzene, of formula (I): wherein n is a number from 0 to 3 and HX represents an inorganic or organic salt. In this process 2-(N-acylaminomethyl)-4-nitrophenol is first reacted with a halogen acetamide to form 2-(2-N-acylaminomethyl-4-nitrophenoxy)acetamide, which is then converted to 2-(N-acylaminomethyl)-4-nitroaniline. Subsequently the 2-(N-acylaminomethyl)4-nitroaniline is reduced to form 1,4-diamino-2-(N-acylaminomethyl)benzene, which is then deacylated by adding hydrochloric acid in a sufficient amount so that 1,4-diamino-2-aminomethylbenzene trihydrochloride is formed. Then the trichloride is converted to the free base form, 1,4-diamino-2-aminomethylbenzene, or to another salt of 1,4-diamino-2-amino-methylbenzene when n≠0 with the proviso that if n=3 HX is not hydrochloric acid. Compositions and methods for dyeing keratin fibers using the compounds of formula I are also described.