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. 05, 1999
Filed:
Jun. 09, 1998
Herbert Tanner, Hanau, DE;
Karlheinz Drauz, Freigericht, DE;
Klaus Stingl, Alzenau, DE;
Gerhard Sator, Dieburg, DE;
Horst Bethge, Rodenbach, DE;
Roland Moller, Hammersbach, DE;
Thomas Tacke, Friedrichsdorf, DE;
Claus Rehren, Aschaffenburg, DE;
Degussa Aktiengesellschaft, Frankfurt, DE;
Abstract
There is provided a process for the work-up of this material having the formula ##STR1## because of its poor crystallizability has heretofore been available only with large yield losses. The yield losses are due to the fact that the crystals of this compound are associated with large amounts of residual solvent material which gives rise to complex and expensive drying procedures. In accordance with the present invention the crude LPE is dried by means of fluid or supercritical carbon dioxide which maces it possible to reduce drying times from the previous range of about 124 hours to about 10 hours for the same amount of product and thus produce a dry LPE which has smaller amounts of residual solvent, as well as smaller by-products than that obtained by conventional drying.