Physical Organic Chemistry of Reactions in Dimethyl Sulphoxide

Buncel, Erwin; Wilson, H.K.

doi:10.1016/s0065-3160(08)60109-4

Cited by 80 publications

(51 citation statements)

References 171 publications

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

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nucleofugalities of Neutral Leaving Groups in 80 % Aqueous Acetonitrile

Jurić¹,

Portolan²,

Kronja³

2016

Croat. Chem. Acta

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“…However, the effects (or lack thereof) by other types of matrix components on the hydrolysis rates of aroma compounds cannot readily be predicted, in light of substantial evidence showing that various organic cosolvents can exert significant influences on the rates of ester hydrolysis, and that the matrix effects are often substrate specific owing to the differing influences on the micro-solvated structures of individual reactants, products, and transition state(s), as well as the effects of aggregation and pK a shifts for various leaving groups (see, e.g., ref. [15][16][17][18][19][20][21][22][23][24][25][26]). …”

mentioning

confidence: 99%

Estimated carboxylic acid ester hydrolysis rate constants for food and beverage aroma compounds

Rayne

Forest

2011

Nat Prec

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Aroma compounds in the Flavornet database were screened for potentially hydrolyzable carboxylic acid ester functionalities. Of the 738 aroma compounds listed in this database, 140 molecules contain carboxylic acid ester groups that may be amenable to hydrolysis in various food and beverage products. Acid- (k~A~) and base- (k~B~) catalyzed and neutral (k~N~) hydrolysis rate constants in pure water at 25°C were estimated for these aroma compounds. Where available, good agreement between theoretical and experimental hydrolytic half-lives was obtained at various pH values. Wide ranges and broad frequency distributions for k~A~, k~B~, and k~N~ are expected among the various hydrolyzable aroma compounds, with estimated k~A~ ranging from 3.7 × 10^-8^ to 4.7 × 10^-4^ M^-1^ s^-1^, estimated k~B~ ranging from 4.3 × 10^-4^ to 43 M^-1^ s^-1^, and estimated k~N~ ranging from 4.2 × 10^-17^ to 7.6 × 10^-9^ M^-1^ s^-1^. The resulting hydrolytic half-lives also range widely, from 10 days to 370 years at pH 2.8, 18 days to 4,900 years at pH 4.0, 1.8 days to 470 years at pH 7.0, and 26 minutes to 5.1 years at pH 9.0. The findings presented herein attest to the importance of considering abiotic hydrolysis and matrix pH when modeling the evolution of sensory characteristics for foods and beverages with carboxylic acid ester based aroma compounds.

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Effect of solvent composition on the acidity of phenols in dimethyl sulfoxide-water mixtures

Tarkka

Xie

et al. 1998

J. Phys. Org. Chem.

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The effect of solvent composition on the acidity of substituted phenols in DMSO-H 2 O systems was examined. It is shown that in DMSO-H 2 O mixtures with up to 35 mol% DMSO there is a linear relationship between the pK a values of monosubstituted phenols in the binary solvent mixtures of different compositions and the corresponding pK a values in water. This leads to an equation relating the slope and intercept terms, pK a (DMSO-H 2 O) = slope[pK a (H 2 O)] intercept. The basis of this relationship in the Kirkwood-Westheimer equation is examined. The significance of a possible 'supersolvent' is discussed. The applicability of the relationships derived herein to other rate-equilibria relationships and solvent mixtures is considered.

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Physical Organic Chemistry of Reactions in Dimethyl Sulphoxide

Cited by 80 publications

References 171 publications

Nucleofugalities of Neutral Leaving Groups in 80 % Aqueous Acetonitrile

Nucleofugalities of Neutral Leaving Groups in 80 % Aqueous Acetonitrile

Estimated carboxylic acid ester hydrolysis rate constants for food and beverage aroma compounds

Effect of solvent composition on the acidity of phenols in dimethyl sulfoxide-water mixtures

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