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US 2008/0167490 A1Published application
Process for the preparation of isocyanates in the gas phase
AssigneeBayer MaterialScience AG
InventorsFritz Pohl, Klaus Biskup, Rainer Bruns, Friedhelm Steffens, Herbert Stutz
Life of this patent
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Abstract
Isocyanates are produced by reaction of primary amines with phosgene in the gas phase. In this process, the reaction is terminated by guiding the reaction mixture from the reaction chamber through a cooling stretch into which liquids are injected. Direct cooling takes place in the cooling stretch in one stage in two or more cooling zones connected in series.
Claims11
A process for the production of an isocyanate by reacting a primary amine with phosgene comprising:
- a) reacting the phosgene and the primary amine in a reaction chamber at a temperature greater than the amine's boiling point within a mean contact time of from 0.05 to 15 seconds to form a gaseous, isocyanate-containing mixture,
- b) cooling the gaseous isocyanate-containing mixture leaving the reaction chamber to condense the isocyanate present therein by direct cooling in one stage in a cooling stretch in two or more cooling zones arranged in series, and
- c) washing the gaseous mixture from step b) with a washing liquid to separate any uncondensed isocyanate from the gaseous mixture.
Dependencies are inferred from the claim text.