Solvation of ions. XIV. Protic-dipolar aprotic solvent effects on rates of bimolecular reactions. Solvent activity coefficients of reactants and transition states at 25°.

Alexander, R.; Ko, E. C. F.; Parker, Alan; Broxton, Trevor J.

doi:10.1021/ja01021a002

Cited by 136 publications

(79 citation statements)

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“…All examined benzhydryldimethylsulfonium, benzhydryltetrahydrothiophenium, and benzhydrylpyridinium salts (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) were prepared according to the procedure described in References 5, 6 and 7.…”

Section: Substrate Preparationmentioning

confidence: 99%

“…[1][2][3] Thus, through judicious choice of solvent, decisive acceleration or deceleration of a chemical reaction can be achieved.…”

Section: Introductionmentioning

confidence: 99%

“…In this work we have investigated the solvolytic reactivities of differently substituted positively charged benzhydrylium salts (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) in the mixture of water and polar aprotic solvent. Thus, examinations have been extended to solvolysis of benzhydryldimethylsulfonium, benzhydryltetrahydrothiophenium, and benzhydrylpyridinium salts (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) in 80 % aqueous acetontirile (v/v) at 25 °C.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, examinations have been extended to solvolysis of benzhydryldimethylsulfonium, benzhydryltetrahydrothiophenium, and benzhydrylpyridinium salts (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) in 80 % aqueous acetontirile (v/v) at 25 °C. The main purpose of this work is to compare the results in aqueous acetonitrile with those obtained in pure and aqueous alcohols, and to establish how the differences in the substrate structures influence the relative rates in aqueous solvents with polar protic and polar nonprotic components, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…The rate of the heterolytic step in SN1 solvolysis of charged substrates (1)(2)(3)(4)(5)(6)(7)(8)(9)(10), similarly as that of neutral substrates, depends on the ability of a leaving group (here neutral leaving group) to depart from a substrate in a given solvent (nucleofugality) as well as on the ability of a carbocation moiety to leave a molecule (electrofugality). [8,9] These parameters have been related in the following special linear free energy relationship (LFER) [Eq.…”

Section: Introductionmentioning

confidence: 99%

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Nucleofugalities of Neutral Leaving Groups in 80 % Aqueous Acetonitrile

Jurić¹,

Portolan²,

Kronja³

2016

Croat. Chem. Acta

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Nucleofugalites of tetrahydrothiophene, dimethyl sulfide and differently substituted pyridines in 80 % aqueous acetonitrile have been derived from the SN1 solvolysis rate constants of the corresponding X,Y-substituted benzhydryl derivatives (1-10). In solvolysis of sulfonium ions in 80 % aqueous acetonitrile, where acetonitrile is a good cation solvator, the solvation of the reactant ground state is an important rate determining variable since the positive charge is almost entirely located on the leaving group. As a consequence, reaction rates of sulfonium ions are more sensitive to the substrate structure in 80 % aqueous acetonitrile than in pure and aqueous alcohols, which are less efficient as cation solvators. In solvolysis of pyridinium ions the solvation of the reactant ground state is less important, since the positive charge is considerably distributed between the carbon at the reaction center and the leaving group. In such cases the important rate determining variable is solvation of the transition state. Slower reactions of pyridinium substrates progress over later, carbocation-like transition states in which the solvation is more important, so those substrates solvolyze slightly faster in aqueous acetonitrile than in methanol (k80AN > kM). Faster reactions proceed over earlier TS in which the solvation is diminished, so those substrates solvolyze somewhat faster in methanol than in aqueous acetonitrile (k80AN < kM).

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