2877-13-6Relevant articles and documents
A novel synthesis of isocyanates and ureas via β-elimination of haloform
Braverman,Cherkinsky,Kedrova,Reiselman
, p. 3235 - 3238 (2007/10/03)
A novel synthesis of isocyanates via base-induced β-elimination of haloform from N-monosubstituted trihaloacetamides is described. The rate of reaction exhibits a strong dependence on the nature of the trihalomethyl group. Thus, while the reaction of tribromoacetamides proceeds at room temperature and the reaction of trichloroacetamides requires heating in polar solvents, no reaction could be observed for any of the corresponding trifluoro derivatives. This novel β-elimination of haloform from stable and readily available trihaloacetamides was applied to a 'one-pot' synthesis of ureas which avoids the use of phosgene and isolation of isocyanates.
Formation of N-Substituted Trichloroacetamides from Amines and Hexachloroacetone
Bew, Clive,Joshi, Virginia Otero de,Gray, Jim,Kaye, Perry T.,Meakins, G. Denis
, p. 945 - 948 (2007/10/02)
Procedures are described for converting primary amines into their well-crystalline trichloroacetyl-derivatives by treatment with hexachloroacetone under mild conditions.Although secondary aromatic N-methylamines are unaffected by hexachloroacetone, saturated heterocyclic amines react vigorously.A mechanistic study using 2-amino-4-t-butylthiazole showed that the reaction is first order in hexachloroacetone, second order in amine, and base-catalysed; there is no appreciable kinetic isotope (H/D) effect nor accumulation of intermediates during the reaction.A sequence which accommodates these results is suggested.
