Kevill, Dennis N.
M.S. (Master of Science)
Department of Chemistry
Organophosphorus compounds; Solvolysis; Organochlorine compounds
The extended Grunwald-Winstein equation has been applied to the solvolyses of two different systems, organo phosphorochloridates and cumyl p-nitrobenzoates, using the Nt scale of solvent nucleophilicity. Kinetic data are reported for the solvolyses of bis-4- (chlorophenyl) phosphorochloridate, N, N, N', N'-tetramethyl- diamidophosphorochloridate and cumyl p-nitrobenzoate, in several pure and mixed aqueous organic solvents. The phosphorochloridates were studied to determine if the Nt scale (developed for attack at a saturated carbon atom) could be applied to attack at phosphorous. Cumyl p- nitrobenzoate was studied to determine if there is nucleophilic solvent assistance present at the cationic transition state in the solvolysis. Results for the solvolyses of the phosphorochloridates indicate that N,N,N',N'-tetramethyldiamidophosphoro- chloridate correlates fairly well with the extended Grunwald-Winstein equation while bis-4-(chlorophenyl) phosphorochloridate does not. The latter compound gave results which were very similar to a related compound which was studied previously, diphenyl chlorophosphate; the two compounds have similar plots of log (k/kQ) versus 1NT + mYcli which show separate branches for each type of solvent system. In the extended Grunwald-Winstein equation, k is the specific rate of solvolysis in a particular solvent, ko is the specific rate of solvolysis in 80% ethanol, m is the sensitivity to the solvent ionizing power (Y) and 1. is the sensitivity to the solvent nucleophilicity (N). The m and 1. values are related to the amount of bond breaking and bond making respectively. The 1 and m values obtained for the compounds indicate that all three solvolyze via a bimolecular process. For the diamido compound, the large 1 (1.2) and large m (0.7) indicate that the compound may react by an addition-elimination type mechanism. The results for bis-4-(chlorophenyl) phosphorochloridate gave an 1 value of 1.02 and an m value of 0.10, indicating an SN2 reaction with bond making running ahead of bond breaking. The results previously obtained for diphenyl chlorophosphate suggest an Sn2 reaction with some addition-elimination also present. The analysis of the cumyl p-nitrobenzoate solvolysis showed that there is only a very modest nucleophilic component present, with a low 1 value of 0.13 and an m value of 0.95.
Miller, Bronwyn, "Application of the extended Grunwald-Winstein equation to solvolysis of phosphorochloridates" (1995). Graduate Research Theses & Dissertations. 1501.
viii, 100 pages
Northern Illinois University
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