Correlation of Rates of Solvolysis of Diphenylacetyl Chloride Using Extended Grunwald-Winstein Equation

摘要

Rate constants for solvolysis involving the displacement of chloride from the carbonyl carbon of diphenylacetyl chloride ((C6H5)(2)CHCOCl, 1) in ethanol, methanol, aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluoroethanol (TFE), and 1,1,1,3,3,3-hexafluoro-2-propanol, and binary mixtures of TFE with ethanol are reported. The kinetic data obtained from the reactions in 34 different solvents and solvent mixtures gave an extended Grunwald-Winstein correlation with the l value of 0.76 +/- 0.06, the m value of 0.34 +/- 0.04, and the correlation coefficient (R-2) of 0.932. The appreciable values for both l and m suggest that the bond formation is ahead of the bond breaking with an S(N)2 mechanism, and the l/m ratio of 2.2 is also in the range of values found for S(N)2 reaction. This interpretation is further supported by the activation parameters, i.e., relatively small positive H (7.7-16.3kcal/mol) values and large negative S (-24.6 to -53.4cal/mol/K) values, and the solvent kinetic isotope effect (1.62).