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:
Apr. 25, 1989
Filed:
Mar. 14, 1988
Otto Arndt, Hofheim am Taunus, DE;
Theodor Papenfuhs, Frankfurt, am Main, DE;
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
Process for the preparation of naphthostyril by dissolving 1,8-naphthalimide in an aqueous solution of lithium hydroxide and potassium hydroxide while heating at 40.degree. C. to 80.degree. C., cooling the solution obtained to 14.degree. C. and seeding it at said temperature with a maximum of 1 mol-% of sodium 1,8-naphthalimide per 1 mol of 1,8-naphthalimide used, then adding chlorine bleaching liquor at 10.degree. C. to 20.degree. C., reductively removing excess active chlorine after the reaction has taken place, adjusting the alkaline aqueous solution produced of the alkali-metal salt of the 1-aminonaphthal-ene-8-carboxylic acid formed to a pH of 2.0 by adding acid and isolating the naphthostyril which precipitates in this process.