34531-53-8Relevant academic research and scientific papers
Sulfonyl transfer from imidazoles
Monjoint, P.,Ruasse, M. F.
, p. 356 - 360 (2007/10/02)
The rate constants for the non-catalyzed bimolecular substitution of 1-tosylimidazole, 1, 1-tosyl-3-methylimidazolium, 2, and 1-tosyl-2,3-dimethylimidazolium, 3, chlorides by primary aliphatic amines (5 n Nu=0.5, 0.5 and 0.6 respectively.Despite large variations in the reactivity, 6 powers of ten from 1 to 2, and in the leaving group pK's, 7 units from 2 to 1, the nucleophile effect is found to be nearly constant.The nucleofuge effect is also independent of the nucleophile; apparent βL-coefficients of approximately - 0.9 are observed whatever the amine.These data correspond to rate-limiting transition states where there is small but significant bonding of the sulfonyl with the entering amines and with the leaving imidazoles.These results strongly suggest a concerted single-step displacement mechanism; however, a stepwise mechanism involving a very unstable and very short-lived pentahedric intermediate cannot be strictly ruled out.These findings are compared with those on other acyl transfers.
