VERFAHREN ZUR HERSTELLUNG VON NIEDERMOLEKULAREN 4,4'-DIPHENYLMETHAN-URETDION-DIISOCYANATEN

• Main Authors: GROEGLER,GERHARD,DR, KOPP,RICHARD,DR
• Format: Patent
• Language: German
• Published: 24.02.1983
• Subjects: APPARATUS THEREFOR; CHEMISTRY; COMPOSITIONS BASED THEREON; GENERAL METHODS OF ORGANIC CHEMISTRY; HETEROCYCLIC COMPOUNDS; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METALLURGY; ORGANIC CHEMISTRY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

Low molecular weight 4,4'-diphenylmethane-uretdione-diisocyanates corresponding to the formula: +TR wherein n is a number from 0 to 1, are made by dimerizing diphenylmethane-4,4'-diisocyanate at a temperature of 50 DEG C. or less in a mixture of non-polar and moderately polar solvents in the presence of a dimerization catalyst. The dimerization product may then be worked up at low temperatures (i.e., </=50 DEG C.). The dimerization products of diphenylmethane-diisocyanate thus obtained generally have only a small amount of oligomeric uretdione-diisocyanates present. These dimerization products may be used advantageously in the synthesis of polyurethanes.