The Effect of Alkyl Group Variation on the Rates of Solvolysis of Alkyl Sulphonium Halides

Hyne, J. B.; Golinkin, H. S.

doi:10.1139/v63-461

Cited by 4 publications

(2 citation statements)

References 2 publications

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“…An interesting observation is that the very small sensitivity of the C−S bond cleavage rate to the stability of the formed carbocation for the sulfide radical cations displayed in Table sharply contrasts with what is observed in the S N 1 solvolysis of sulfonium salts (eq , R = tert -alkyl, arylalkyl, or diarylalkyl) , a reaction that formally strongly resembles the C−S bond cleavage in sulfur radical cations (eq ), the only difference being that in eq the leaving group is a sulfur radical, whereas in eq it is a neutral sulfide. In this case, the stabilization of the incipient carbocation is the dominant factor affecting the solvolysis rate .…”

Section: Discussionmentioning

confidence: 91%

Structure and C−S Bond Cleavage in Aryl 1-Methyl-1-arylethyl Sulfide Radical Cations

et al. 2010

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Steady state and laser flash photolysis (LFP) of a series of p-X-cumyl phenyl sulfides (4-X-C(6)H(4)C(CH(3))(2)SC(6)H(5): 1, X = Br; 2, X = H; 3, X = CH(3); 4, X = OCH(3)) and p-X-cumyl p-methoxyphenyl sulfides (4-X-C(6)H(4)C(CH(3))(2)SC(6)H(4)OCH(3): 5, X = H; 6, X = CH(3); 7, X = OCH(3)) has been carried out in the presence of N-methoxy phenanthridinium hexafluorophosphate (MeOP(+)PF(6)(-)) under nitrogen in MeCN. Steady state photolysis showed the formation of products deriving from the C-S bond cleavage in the radical cations 1(+•)-7(+•) (2-aryl-2-propanols and diaryl disulfides). Formation of 1(+•)-7(+•) was also demonstrated by LFP experiments evidencing the absorption bands of the radical cations 1(+•)-3(+•) (λ(max) = 530 nm) and 5(+•)-7(+•) (λ(max) = 570 nm) mainly localized in the arylsulfenyl group and radical cation 4(+•) (λ(max) = 410, 700 nm) probably mainly localized in the cumyl ring. The radical cations decayed by first-order kinetics with a process attributable to the C-S bond cleavage. On the basis of DFT calculations it has been suggested that the conformations most suitable for C-S bond cleavage in 1(+•)-4(+•) and 7(+•) are characterized by having the C-S bond almost collinear with the π system of the cumyl ring and by a significant charge and spin delocalization from the ArS ring to the cumyl ring. Such a delocalization is probably at the origin of the observation that the rates of C-S bond cleavage result in very little sensitivity to changes in the C-S bond dissociation free energy (BDFE). A quite large reorganization energy value (λ = 43.7 kcal mol(-1)) has been calculated for the C-S bond scission reaction in the radical cation. This value is much larger than that (λ = 12 kcal mol(-1)) found for the C-C bond cleavage in bicumyl radical cations, a reaction that also leads to cumyl carbocations.

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Section: Discussionmentioning

confidence: 91%

Structure and C−S Bond Cleavage in Aryl 1-Methyl-1-arylethyl Sulfide Radical Cations

et al. 2010

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“…In the time required to complete a density measurement (about 1.5 h ) some 5-7% of the sulfonium ion would undergo solvolysis at 50.0 OC. The half lives for the reaction at 50.3 OC are -30 h (k = 6.3 x s-') in water and -22 h (k = 8.5 x s-') in 0.325 mole fraction ethanol (14). The partial molal volumes of Me4NI were also determined at 25 "C so that the errors in the value used for V, , i.e.…”

Section: Partial Molal Volumesmentioning

confidence: 99%

Effect of Pressure on the Solvolysis of Dimethyl-t-butyl Sulfonium Iodide in Ethanol–Water Mixtures

Davis¹,

Hyne²

1972

Can. J. Chem.

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The pressure dependence of the rate of solvolysis of dimethyl-t-butyl sulfonium iodide has been studied in ethanol-water mixtures at 60.00 "C. Determination of the partial molal volume of the substrate ions has enabled the volumes of activation to be dissected into initial and transition state components. The solvent composition dependence of the partial molal volumes of the two states provides further details of the nature of the reaction mechanism. L'influence de la pression sur la vitesse de solvolyse de I'iodure de dimethyl-I-butylsulfonium a etC etudiee dans des melanges eau-alcool i 60.00 O C . La determination du volume molaire partiel des ions substrats a rendu possible la division des volumes d'activation en composantes Ctat initial et &at de transition. L'influence de la composition du solvant sur les volumes molaires partiels des deuxttats fournit des details supplementaires sur la nature du mecanisme de la rtaction.

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Cyanogenesis in manioc: Concerning lotaustralin

et al. 1969

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The Effect of Alkyl Group Variation on the Rates of Solvolysis of Alkyl Sulphonium Halides

Abstract: ~v i t h water, and dried to leaye 0.12 g ( 2 4 5 ) , m.p. 262-273". This material n a s identical n i t h that obtained in procedure *A n ith respect to infrared and ultraviolet spectra and paper chronlatographic b e h a~i o r .

Cited by 4 publications

References 2 publications

Structure and C−S Bond Cleavage in Aryl 1-Methyl-1-arylethyl Sulfide Radical Cations

Structure and C−S Bond Cleavage in Aryl 1-Methyl-1-arylethyl Sulfide Radical Cations

Effect of Pressure on the Solvolysis of Dimethyl-t-butyl Sulfonium Iodide in Ethanol–Water Mixtures

Cyanogenesis in manioc: Concerning lotaustralin

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