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Aminolysis and hydrolysis of sulphamate esters: Substantial NS bonding in the transition state leading to Nsulfonylamines
Author(s) -
Spillane William J.,
Hogan Geraldine,
McGrath Paul
Publication year - 1995
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610080907
Subject(s) - aminolysis , chemistry , kinetic isotope effect , aqueous solution , amine gas treating , hydrolysis , acetonitrile , medicinal chemistry , solvent , substrate (aquarium) , stereochemistry , deuterium , inorganic chemistry , organic chemistry , catalysis , physics , quantum mechanics , oceanography , geology
The aminolysis and hydrolysis of several sulphamate esters, RNHSO 2 ONp (R = PhCH 2 , Ph, 4‐MeC 6 H 4 4, 3‐MeC 6 H 4 , 4‐FC 6 H 4 , 4‐ClC 6 H 4 , 3‐ClC 6 H 4 , H; Np = 4‐NO 2 C 6 H 4 ) were been studied in 50% (v/v) aqueous acetonitrile at various temperatures. Reaction of the esters with an amine (R 1 NH 2 ) gives − ONp and both sulphamide, (RNHSO 2 NHR 1 ) and sulphamate (RNHSO 2 O − R 1 NH 3 + ) products. First‐order rates were determined by the appearance of − ONp and sometimes also by the disapperance of ester. The reaction was found to be independent of amine type and concentration and at the high pHs that obtain the substrate esters are fully ionized. A Hammett ρ acyl of −;1·8 was obtained for the decomposition of the sulphamate anions and this is consistent with substantial NS bonding in the transition state leading to N‐sulphonylamine, RNSO 2 . This intermediate then partitions very rapidly, reacting with R 1 NH 2 and H 2 O respectively. Δ H ‡, Δ S ‡ and a deuterium solvent isotope effect were determined and were also interpreted in favour of the proposed mechanism. The dimethyl sulphamate ester (Me 2 NSO 2 ONp) does not react under the conditions used.