Dual Roles of N,N-Dimethylformamide in Benzothiazoles Synthesis from N-Benzoyl-N′-(2,4,6-trichlorophenyl)thiourea

N,N-Dimethylformamide (DMF) is not only a common polar solvent in chemistry, but also a reaction reagent, a catalyst and a stabilizer. In this paper, a new reaction was found accidently where DMF acted as both solvent and catalyst. By dissolving N-benzoyl-N′-(2,4,6-trichlorophenyl)-thiourea (BAD) in DMF and evaporating the solvent slowly, single crystals were obtained but their composition was determined to be 2-benzoylamino-4,6-dichloro-benzothiazole (BTT) with DMF molecule (BTT–DMF), not BAD. The single crystals of BAD could be obtained by crystallization from the solvents of acetonitrile or ethanol. The crystal structures of BAD and BTT–DMF were measured and analysed. Based on the hydrogen bonding interactions in their crystal structures, a possible reaction mechanism was proposed. All in all, DMF is a really multifunctional chemical, it may still have other potential functions which are interesting and valuable to be developed. A new reaction was found by dissolving N-benzoyl-N′-(2,4,6-trichlorophenyl)-thiourea (BAD) in DMF and evaporation of the solvent slowly to grow single crystals.