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. 17, 1990
Filed:
Oct. 02, 1985
Siegbert Rittner, Morfelden-Walldorf, DE;
Herbert Gortz, Frankfurt am Main, DE;
Knut Riedel, Hofheim am Taunus, DE;
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
The invention relates to a process for the preparation of pure cis- or trans-crotonic acid from a mixture of the two isomers by melt crystallization. To prepare trans-crotonic acid, an isomer mixture I containing at least 40% by weight of trans-crotonic acid is used as the starting material. On the other hand, if cis-crotonic acid is to be prepared, an isomer mixture II containing at least 80% by weight of cis-crotonic acid is used as the starting material. The particular isomer mixture is melted and then left to cool, trans-crotonic acid being allowed to crystrallize out of mixture I to a residual content of at least 35% by weight, and cis-crotonic acid being allowed to crystallize out of mixture II to a residual content of at least 75% by weight.