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. 18, 1983
Filed:
Jul. 21, 1981
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
The preparation of 3-amino-1-phenylpyrazol-5-one by heating phenylhydrazine and a lower cyanoacetic acid alkyl ester in a polar solvent, using a lower alcoholate of an alkali metal as the condensation agent, leads to particularly high yields and quality, if the phenylhydrazine and 1 to 1.2 moles of the alcoholate are initially taken, the cyanoacetic ester is metered in and the reaction is carried out at 105.degree. to 140.degree. C., volatile alcohols which have been liberated from the ester and, if appropriate, from the alcoholate being distilled off at the reaction temperature. It is advantageous to employ the phenylhydrazine in an excess of up to about 200 mole % and to select, as the polar solvent, an alcohol or ether having a boiling point above 105.degree. C.