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:
Sep. 19, 1978
Filed:
Apr. 19, 1977
Hans Jakob Schladetsch, Frankfurt am Main, DE;
Gunther Schroth, Muhlheim, Main, DE;
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
Process for the manufacture of a disazo dyestuff of the formula ##STR1## in which R.sub.1 and R.sub.2 each stand for hydrogen, chlorine, bromine, alkyl of 1 to 4 carbon atoms or alkoxy of 1 to 4 carbon atoms, R.sub.3 and R.sub.4 each stand for hydrogen, chlorine, bromine, nitro, trifluoromethyl, alkyl of 1 to 4 carbon atoms or alkoxy of 1 to 4 carbon atoms; and the hydroxyl groups each stand in 2- or 4-position to the azo groups which comprises diazotizing a 2- or 4-hydroxy-4'-aminoazobenzene of the formula ##STR2## in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are defined as above, with an alkali metal nitrite in an aqueous mineral acid, the normality of which being about 10.sup.-2 to 5, in the presence of a phenol capable of being coupled of the formula ##STR3## in which R.sub.1 and R.sub.2 are defined as above and subsequently reacting the diazonium salt obtained with the phenol by raising the pH to a value between about 3 and 11, the surprising feature of this process (diazotization in the presence of the phenol) being that practically no nitrozation or a nitration of the phenol occurs.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile