This work aims to unravel the origin of the positive ortho-effect in solvolysis reactions of hindered arenesulfonyl chlorides. The alcoholysis in methanol, ethanol, propanol and iso-propanol, at 313 K, of hindered X-ArSO2Cl (X=4-Me; 4-Br-; H-; 2,4,6‑Me3-; 2,6‑Me2‑4-t-Bu-; 2,3,5,6-Me4-; 2,4,6‑Me3-3-NO2-; 2,4,6-i-Pr3-) was investigated. X-ray analysis was carried out in solid crystals of hindered arenesulfonyl chlorides and arenesulfonates. The hypothesis of C-H···O intramolecular interactions in these compounds was discussed. A SN2‑like transition state, with nucleophilic assistance of a second alcohol molecule was proposed. Empirical data support the change from nucleophile’s backside attack to frontal attack when moving from unhindered compounds to ortho‑alkyl substituted.
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Relations structure-reactivity and the positive steric effects of ortho substituents in arenesulfonyl chlorides
Published: 30 October 2015 by MDPI in The 19th International Electronic Conference on Synthetic Organic Chemistry session Ionic Liquids
Keywords: alcoholysis, hindered arenesulfonyl chlorides, positive ortho-effect, frontal attack, nucleophilic assistance of nucleophile, X-ray analysis