In this chapter we have encountered many examples of SN1 solvolysis reactions, all of which proceed according to the following scheme:

Upon mixing the colorless substrate and solvent, a reddish-orange color is observed immediately, signaling the formation of an intermediate carbocation. This color fades over a period of about a minute, and analysis of the solution reveals the presence of the final product in 100% yield
(a) There are two reasons for the buildup of a detectable concentration of carbocation in this case. One is that the carbocation derived from dissociation of this particular substrate is unusually stable. The other is that the solvent (2.2.2-trifluoroethanol) is an unusually poor nucleophile, even compared with ordinary alcohols such as ethanol. Suggest an explanation for the poor nucleophilicity of the solvent
(b) What can you say about the relative rates of the two steps (rate, and rate2), and how do they compare to those in the usual SN1 reaction mechanism?
(c) How might increasing carbocation stability and decreasing solvent nucleophilicity affect the relative magnitudes of rate1 and rate2 in an SN1 process?
(d) Write the complete mechanism for the reaction above.

Transcribed Image Text:

CH2CF3 Cl CF,CH OH CH3O OCH3