THE ROLE OF ELIMINATION PROCESSES IN THE REACTION OF SUBSTITUTED UREAS AND THIOUREAS WITH CHLORIDES OF MONOFUNCTIONAL AND BIFUNCTIONAL ACIDS

The reaction of phthaloyl chloride 2 with 1,3-dimethylurea 1 in dichloromethane at room temperature leads to the formation of N,N-1,1'-phthaloyl-bis(1,3-dimethylurea) 3 whereas in refluxing solvent N-methyl-phthalimide 4 is the principal product. The reaction of 1,3-bis(trimethylsilyl)-1,3-dimethylurea 5 separately with phthaloyl- 2, 4-nitrobenzoyl- 6, and 5-chlorothiophene-2-carbonyl chloride 9 results in the formation of 1,3-phthaloyl-1,3-dimethylurea 7, 1,3-bis(4-nitrobenzoyl)-1,3-dimethylurea 8, and N,N-bis(5-chlorothiophene-2-carbonyl)-N-methylamine 12, respectively. The reaction of N,N-bis-(trimethylsilyl)acetamide 11 with 9 furnished N,N-bis(5-chlorothiophene-2-carbonyl)-acetamide 13, while the reaction of 13 with 1,3-dimethylthiourea 10 afforded 1,3-dimethyl-1,3-bis(5-chlorothiophene-2-carbonyl)thiourea 14. The structures of 3 and 12 were confirmed by low temperature X-ray crystallography. Both display crystallographic twofold symmetry.