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:
Aug. 04, 1992
Filed:
Aug. 30, 1990
Jack Chosnek, Corpus Christi, TX (US);
George E Beck, Portland, TX (US);
Donna L Keene, Carrollton, VA (US);
Siegbert Rittner, Morfelden-Walldorf, DE;
Volker Hautzel, Florsheim, DE;
Hoechst Celanese Corporation, Somerville, NJ (US);
Abstract
The present invention relates to a process for the purification of 4-acetoxystyrene from a crude product mixture comprising 4-acetoxystyrene and typically 5 or more contaminants in substantial amount. The crude product mixture is purified by melt crystallization by cooling the mixture to a temperature ranging from about +8.degree. C. to about -50.degree. C., whereby at least a first portion of the mixture is crystallized; removing the liquid remaining from contact with the crystallized first portion of the mixture; and, subsequently slowly heating the crystallized first portion, while simultaneously removing liquid which forms due to the heating, whereby impurities contained in the liquid which forms are removed from the crystallized first portion. Surprisingly, despite the large number of contaminants present, and use of the process to purify crude product mixtures containing as little as 50% by weight 4-acetoxystyrene, purities as high as 99.9% by weight have been obtained using multiple melt-crystallization steps of the process of the invention.