Crystal structures of arylsulfonylation products of 2-alkyl-5-substituted-1<i>H</i>-benzimidazoles
Abstract
Mixed crystals of 1-(4-chlorophenylsulfonyl)-2,5-dimethyl-1 H -benzimidazole and 1-(4-chlorophenylsulfonyl)-2,6-dimethyl-1 H -benzimidazole (ratio 0.707:0.293; two molecules in the asymmetric unit), 0.707C 15 H 13 ClN 2 O 2 S·0.293C 15 H 13 ClN 2 O 2 S, ( I ), and of 2- n -butyl-1-(4- tert -butylphenylsulfonyl)-5-chloro-1 H -benzimidazole and 2- n -butyl-1-(4- tert -butylphenylsulfonyl)-6-chloro-1 H -benzimidazole [ratio 0.731 (2):0.269 (2); one molecule in the asymmetric unit], 0.731C 21 H 25 ClN 2 O 2 S·0.269C 21 H 25 ClN 2 O 2 S, ( II ), were obtained from the arylsulfonylation reaction of the corresponding 2-alkylbenzimidazoles. In addition, two products were obtained from the reaction of 2- n -butyl-5-chloro-1 H -benzimidazole with 4-methylbenzenesulfonyl chloride. These reaction products were separated by column chromatography and the crystal structure of one of the products, 2- n -butyl-5-chloro-1-(4-methylphenylsulfonyl)-1 H -benzimidazole (one molecule in the asymmetric unit), C 18 H 19 ClN 2 O 2 S, ( III ), was determined. In the crystal structures of ( I )–( III ), there is a difference in the arrangement of the planar benzimidazole and arylsulfonyl fragments. The formation of weak C—H...O hydrogen-bonding interactions is characteristic of all three crystal structures.