Imidazoles chlorosulfonation

Sulfonation conditions are given in Table 4. The orientation is as expected. Azolinones react as readily as the corresponding azoles sulfonation of (117) occurs at the positions indicated (H2SO4/SO3 at 100 °C). Imidazoles are readily chlorosulfonated at C-4. 

Imidazole, 2-amino-1 -methyl-4,5-diphenyl-tautomerism, 5, 368 Imidazole, 2-aroyl-mass spectra, 5, 360 synthesis, 5, 391, 402 UV spectra, 5, 356 Imidazole, 4-aroyl-synthesis, 5, 474 Imidazole, C-aroyl-UV spectra, 5, 356 Imidazole, aryl-nitration, 5, 396, 433 oxidation, 5, 433 Imidazole, 1-aryl-dipole moments, 5, 351 dearylation, 5, 449 ethylation, 5, 448 H NMR, 5, 353 hydroxymethylation, 5, 404 rearrangement, 5, 108 synthesis, 5, 390 thermal rearrangement, 5, 363 Imidazole, 2-aryl-chlorosulfonation, 5, 397 synthesis, 5, 475 Imidazole, 4-aryl-bromination, 5, 399 Imidazole, C-aryl-electrophilic substitution, 5, 432-433 nitration, 5, 433 Imidazole, N-aryl-reactions, 5, 448-449 structure, 5, 448-449 Imidazole, arylmercapto-... 

Chlorosulfonation of 4-bromo-, 4-chloro-l-methyl-, 5-chloro-l-methyl- and a series of 2-aryl-imidazoles occurs also at C-4 (or C-5), but only decomposition products were isolated from the reaction with 4-acetamidoimidazole. 

The PPE is sulfonated in chloroform solution with chlorosulfonic acid. After isolation of the sulfonated PPE, the imidazole complex is formed in A,A-dimethyfformamide solution by adding sulfonated PPE and... 

Imidazole 44 reacts with excess chlorosulfonic acid to give an excellent yield of the 4-sulfonyl chloride 45 (Equation 10) the chlorosulfonation was also achieved by heating the heterocycle 44 with chlorosulfonic acid (1.5 equivalents) in excess thionyl chloride (Equation 10). ... 

The action of chlorosulfonic acid on 2-(4-chlorophenyl)imidazole also gave the 4-sulfonyl chloride with preferential substitution occurring in the imidazole ring rather than in the phenyl nucleus - presumably the orientation is as a result of favourable stereoelectric factors. ... 

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