| US 7,524,405 B2 | ||
| Method for separating out solvent from a reaction mixture resulting from an isocyanate synthesis and for purifying this solvent | ||
| Martin Sohn, Mannheim (Germany); Eckhard Stroefer, Mannheim (Germany); Filip Nevejans, St.Gillis-Waas (Belgium); Ulrich Penzel, Tettau (Germany); Hans-Juergen Pallasch, Kallstadt (Germany); Peter Van Den Abeel, Brasschaat (Belgium); Filip Deberdt, Muizen (Belgium); Jan D. Jacobs, Baton Rouge, La. (US); and Wolfgang Mackenroth, Bad Duerkheim (Germany) | ||
| Assigned to BASF Aktiengesellschaft, Ludwigshafen (Germany) | ||
| Appl. No. 10/539,610 PCT Filed Dec. 13, 2003, PCT No. PCT/EP03/14187 § 371(c)(1), (2), (4) Date Jun. 17, 2005, PCT Pub. No. WO2004/056761, PCT Pub. Date Jul. 08, 2004. |
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| Claims priority of application No. 102 60 027 (DE), filed on Dec. 19, 2002. | ||
| Prior Publication US 2006/0011463 A1, Jan. 19, 2006 | ||
| Int. Cl. B01D 3/00 (2006.01); C07C 263/20 (2006.01) | ||
| U.S. Cl. 203—80 [203/27; 203/DIG. 8; 560/347; 560/352] | 18 Claims |
| 1. A process for preparing at least one isocyanate, comprising:
reacting at least one amine with phosgene in the presence of at least one inert organic solvent in a reactor; and
working up the reaction mixture leaving the reactor,
wherein the at least one solvent is separated off from the at least one isocyanate in an at least a two-stage distillation
process in which the at least one solvent is separated off at a pressure of from 0.1 to 15 bar in a first apparatus in the
first stage and at from 1 to 900 mbar in a second apparatus in the second stage,
wherein the heat of condensation of a solvent vapor from the first apparatus is utilized for vaporization of solvent in the
second apparatus.
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