Dimethyl N-Aryl phosphoramidates : structural effects on bonding and solvolytic reactivity
Master Thesis
1981
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University of Cape Town
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Abstract
The acid catalysed hydrolysis of a number of ring alkyl substituted dimethyl N-aryl phosphoramidates, (MeO)2P(0)NHAr, has been studied by measuring the rates of hyd~olysis with the aid of a UV spectrophotometer. These rates have been correlated with the pKa values of the corresponding ani I inium iOhs and the slope of this reactivitybasicity relationship for phosphoramidate with ortho substituents (6 = 0~85) is found to differ from that for substrates with meta and para substituents (S = 0,36). Determination of the thermodynamic parameters indicates that the entropy of activation is approximately constant for the substrates studied and the strongly negative values ~ -I -I (~S = 155,4 - 17,5 J mole K ) are consistent with an A2 type mechanism.
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Bibliography: p. 84-86.
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Reference:
Rijkmans, B. 1981. Dimethyl N-Aryl phosphoramidates : structural effects on bonding and solvolytic reactivity. University of Cape Town.