Participation by Ether Oxygen (RO-3) in the Hydrolysis of Sulfonate Esters of 2-Methoxyethanol and 2-Methoxy-2-methyl-l-propanol. Implications Regarding the Nonlinear Ethanol-Trifluoroethanol Plot for Mustard Chlorohydrin
The lack of scrambling with deuterium-labeled reactants, a nonlinear ethanol-trifluoroethanol plot, and rate acceleration by added thiourea are used to show that sulfonate esters of methoxyethanol (MeOCH2CH2OH) undergo solvent-assisted displacement in a variety of solvents; neighboring group participation by ether oxygen (RO-3 participation) does not occur. This conclusion is in accord with predictions of rate based on the Taft treatment of substituent effects. On the other hand, the branched derivative MeOCMe2CH2OBs reacts with concerted RO-3 participation to give completely rearranged product. Its solvolysis rate is insensitive to added thiourea, the Taft treatment predicts modest anchimeric assistance, and a linear ethanol-trifluoroethanol plot is observed. We discuss the implications of these results relative to the previously observed nonlinear plot for mustard chlorohydrin.
McManus, S. P., R. M. Karaman, R. Sedaghat-Herati, N. Neamati-Mazraeh, B. A. Hovanes, M. S. Paley, and J. M. Harris. "Participation by ether oxygen (RO-3) in the hydrolysis of sulfonate esters of 2-methoxyethanol and 2-methoxy-2-methyl-1-propanol. Implications regarding the nonlinear ethanol-trifluoroethanol plot for mustard chlorohydrin." The Journal of Organic Chemistry 52, no. 12 (1987): 2518-2522.
Journal of Organic Chemistry