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. 21, 1980
Filed:
Mar. 28, 1979
Jurg Kiefer, Reinach, CH;
Theobald Haug, Frenkendorf, CH;
Ciba-Geigy Corporation, Ardsley, NY (US);
Abstract
In the production of maleimides of the general formula I ##STR1## in which n is one of the numbers 1, 2 or 3, R.sup.1 and R.sup.2 are each a hydrogen atom or methyl, and A is an n-valent aliphatic, cycloaliphatic, aliphatic-cycloaliphatic or aliphatic-aromatic radical having up to 30 C atoms, by means of cyclising dehydration of a maleamic acid of the formula II ##STR2## in which the acid amide group (s) is (are) attached to aliphatic or cycloaliphatic C atoms, in the presence of low-molecular dehydrating carboxylic anhydrides in an organic solvent and in the present of catalysts, there is advantageously used as solvent a polar aprotic solvent containing at least one N-lower-alkyl-substituted acid amide group in the molecule, or a solvent mixture containing an aprotic solvent of this type, and as catalyst a metal compound, and the cyclising dehydration is performed in the temperature range of 40.degree. to 100.degree. C.