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:
Jul. 13, 1993
Filed:
Oct. 07, 1992
Ralf Pfirmann, Griesheim, DE;
Theodor Papenfuhs, Frankfurt am Main, DE;
Klaus Forstinger, Kelsterbach, DE;
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
The present invention relates to a process for the preparation of isomerically pure 2-nitro-5-fluoro- or -5-chlorophenol, by reacting 2,4-difluoronitrobenzene or 2,4-dichloronitrobenzene with aqueous alkali metal or alkaline earth metal hydroxide solution or suspension in the absence of organic solvents or other solubility promoting substances at temperatures from about 20.degree. C. to about 190.degree. C., adjusting the pH of the reaction mixture to about 1 to about 6 by the addition of acid, steam distilling the resultant product and isolating it from the distillate after cooling.