Patent ID: 6624301
Filing Date: 2003-09-23
Classification: C07D,C08G,C08K

Abstract:
Process for the preparation of (cyclo)aliphatic uretdiones consisting essentially of:contacting a (cyclo)aliphatic diisocyanate and from 0.5 to 3% by weight of a catalyst of formula (I) in which R1 and R2 are identical or different alkyl radicals of 1 to 8 carbon atoms or, together with the nitrogen atom to which they are attached, form a 5-membered or 6-membered ring which can contain a CH-CH3 group, a N-CH3 group or an oxygen atom in said ring, in the presence of from 0.1 to 4% by weight of a phosphorus compound of formula (II) in which R3 and R4 are identical or different aromatic or araliphatic hydrocarbon radicals of 1 to 10 carbon atoms or are OR1 or OH, to effect dimerization, said contacting first being carried out at a temperature from 0 to 60Â° C. up to 5 to 70% conversion and then isolating a residue containing 1,3-diazacyclobutane-2,4-dione from the reaction mixture by thin-film distillation, without prior deactivation of the catalyst and the phosphorus compound, and isolating a distillate containing the catalyst, phosphorus compound and unreacted diisocyanate.