Studies in Solvolysis. Part IV. Substituent and Solvent Isotope Effects in the Solvolysis of a Series of Benzyl Trifluoroacetates

Abstract

The rates of neutral hydrolysis of a series of 4-substituted benzyl trifluoroacetates 4-X-C,H,CH,OCOCF,, X = NO,, C1, H, CH,, and OCH, have been studied in water and deuterium oxide, both solvents containing 0.012 mol fraction of acetone. The alteration of the rates with the nature of the 4-substituent and the kinetic solvent isotope effect (k(H,O)/k(D,O)) are consistent with the proposal that the esters with X = NO,, CI, H, and CH, all react by an acyl-oxygen BA,2 mechanism. On the other hand, the same mechanistic criteria indicate that the 4-methoxybenzyl ester reacts by both the BA,2 and the S,1 alkyl-oxygen fission paths in equal amounts.

Studies in Solvolysis. Part VI. An Examination of the Heat Capacity of Activation for the Hydrolysis of 4-Methoxybenzyl Trifluoroacetate

“…The 4-substituted-benzyl trifluoroacetates were prepared and their purity established as previously described (7). Acetone was treated with potassium permanganate, dried with anhydrous potassium carbonate, and distilled (b.p.…”

“…The mechanistic bifurcation postulated in the case of 4-methoxybenzyl trifluoroacetate was originally devised to account for the deviation from a Hammett plot as well as an unusual value for the solvent isotope effect k(H20)/k(D20) observed for this ester (7). The same hypothesis is capable of explaining the unique positive heat capacity of activation for this process.…”

Benzyl acetates as attractants for the male oriental fruit fly, Dacus dorsalis , and the male melon fly, Dacus cucurbitae

“…This article must therefore be hereby marked "advertisement" in accordance with (10), and pmethoxybenzyl thiolacetate (XLV) was from p-methoxybenzenethiol and acetic anhydride (11). Benzyl a,a,atrifluoroacetate (XLII) was prepared from benzyl alcohol and trifluoroacetic anhydride (12), and benzyl a-fluoroacetate (XLI) was prepared from benzyl bromide and sodium fluoroacetate by the method of Gomberg and Buchler (13).…”