Solvent Effects on the Solvolysis of p-Nitrobenzyl and 3,5-Bis(trifluoromethyl)benzyl p-Toluenesulfonates

Abstract

Solvolysis rates of p-nitrobenzyl and 3,5-bis(trifluoromethyl)benzyl p-toluenesulfonates were determined in a wide variety of solvents. The solvent effects were analyzed based on the Winstein–Grunwald equation. The solvent effect on these deactivated benzyl solvolyses failed to give a single linear correlation with the 2-adamantyl YOTs parameter. The lower response to the solvent polarity and the pattern of dispersion for respective binary solvent series can be interpreted in terms of nucleophilic solvent assistance. The application of the equation gave a low m value of 0.4 and a large l of close to unity for both derivatives. Furthermore, the l value is also comparable to that for ethyl p-toluenesulfonate and even close to that for the methyl derivative, which has generally been defined as the standard SN2 substrate.

Correlation of the rates of solvolysis of arylmethylp-toluenesulfonates: application of the aromatic ring parameter and a discussion of similarity models

“…[1], with and without the lN T term, using the ABSTAT statistical package (Anderson-Bell, Arvada, Colorado, U.S.A.). The results of this analysis are contained within Table 2, together with identical analyses of the five more extensively studied (in terms of number of solvents) substrates, using the data of Fujio, Tsuno, and co-workers (6,7). When values for solvolyses in acetonitrile-water mixtures are reported (6, 7), the appropriate secondary N′′ T values (12) were used, in conjunction with the N T values available (9, 10) for the other solvents.…”

“…Satisfactory analyses were obtained with use of either N Et 3 O + (2) or N OTs (3) solvent nucleophilicity values, in conjunction with Y OTs solvent ionizing power values (3)(4)(5); the sensitivities to changes in solvent nucleophilicity (l values) became larger as increasingly electron-withdrawing substituents were introduced. Subsequently, reports of studies (with analyses in terms of N OTs and Y OTs ) of the specific rates of solvolysis in [35][36][37][38][39][40][41][42] solvents of the parent compound (6) and derivatives with X = m-methyl (6), m-chloro (6), p-nitro (7), and 3,5-di(trifluoromethyl) (7) have appeared.…”

“…Since the previous reports (1,6,7), a new type of scale has been developed for incorporation into the Grunwald-Winstein equations when the solvolyses involve benzylic derivatives (14). This scale is termed the aromatic ring parameter (I) and the sensitivity to changes in this value is termed h. The full equation is now represented by eq.…”

“…In the present report, we analyze the specific rates of solvolysis of several compounds of structure 1, with varying identity of substituent X (1,6,7), in terms of both simple (eq. [1] without the lN term) and extended (eq.…”

The kinetics and mechanisms of organic reactions in liquid ammonia

“…202 The rate of solvolysis in liquid ammonia is retarded dramatically when one of methylene hydrogen of benzyl chloride in the α-position is replaced by a methyl group, α-methyl benzyl chloride is solvolysed about 130 times slower than benzyl chloride. This is strong evidence for solvolysis occurring by an S N 2 mechanism due to a more sterically hindered transition state.…”