Solvolysis rates and deuterium isotope effects in 2,2,2-trifluoroethanol-water mixtures

Shiner, V. J.; Dowd, William; Fisher, Robert D.; Hartshorn, S. R.; Kessick, M. A.; Milakofsky, Louis; Rapp, Magdalena

doi:10.1021/ja01045a043

Cited by 77 publications

(38 citation statements)

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“…We adopt the same approach here in following a treatment proposed by Murr and Donnelly (41). Assume that a stepwise mechanism of minimal complexity can be represented by reaction [4]. If intimate ion pair 2 partitions between internal 1 2 3 return to 1 and irreversible dissociation to loose ion pair 3, such that k3 >> k-2, then the observed chlorine isotope effect is given by eqs.…”

Section: Isotope Effects In Multistep Mechanismsmentioning

confidence: 99%

See 1 more Smart Citation

Chlorine isotope effects in the solvolysis of substituted 1-phenylethyl chlorides

McLennan¹,

Stein²,

Dobson³

1986

Can. J. Chem.

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Kinetic chlorine isotope effects attending the solvolysis of several ring-substituted 1-phenylethyl chlorides in alcohol-water solvent mixtures are reported. The k35/k37 values are insensitive to the identity of ring substituents and to solvent composition. Results are interpreted in terms of an SN1 heterolytic process incorporating a significant amount of internal return. Theoretical calculations suggest that the incipient chloride ion in the transition state may be strongly hydrogen-bonded. On a mesurt les effets isotopiques cinttiques du chlore qui accompagnent les solvolyses de plusieurs chlorures de phtnyl-1 Cthyle substituts sur le cycle. Les valeurs de k35/k37 sont insensibles h la nature des substituants sur le cycle ainsi qu'h la composition du solvant. On interprbte les rtsultats en fonction d'un processus htttrolytique SN1 incorporant une part importante de retour interne. Des calcultes thkoriques suggbrent que I'ion chlorure qui attaque dans l'ttat de transition pourrait Ctre fortement lit par des liaisons hydrogbnes.[Traduit par la revue]

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Section: Isotope Effects In Multistep Mechanismsmentioning

confidence: 99%

“…Kinetic (I), stereochemical (2), secondary a-and P-deuterium isotope effect (3,4), and carbon isotope effect (5-8) studies have been reported. Recent work has focussed on the generation and the fate of substituted 1-phenylethyl cations in solution as a function of their lifetimes (9)(10)(11).…”

Section: Introductionmentioning

confidence: 99%

Chlorine isotope effects in the solvolysis of substituted 1-phenylethyl chlorides

McLennan¹,

Stein²,

Dobson³

1986

Can. J. Chem.

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“…Chlorirle p-Methylbenzyl chloride has been extensively investigated both with regard to solvolytic activation parameters (5 -7) and precision Hdeuterium kinetic isotope effects (3,8). This compound was selected as a convenient refpr.cnce J:,,sletn for our studies.…”

Section: Resultsmentioning

confidence: 99%

Sterically Hindered Aromatic Compounds. V. Solvolysis of p-Methyl-, 2,4,6-Trimethyl-, and 2,4,6-Tri-t-butylbenzyl Chloride. Effect of Solvent and α-Deuterium Substitution

Barclay¹,

Mercer²,

Hudson³

1972

Can. J. Chem.

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Rates, activation parameters, and kinetic a-deuterium isotope effects are reported for solvolysis ofp-methylbenzyl chloride in 80% trifluoroethanol-water, and in ethanol-water and I-butyl alcohol-water of varying solvent compositions. The a-deuterium isotope effect in trifluoroethanol-water (kH/kD = 1.14 per D) indicates approximately limiting behavior. Results in the other solvents (kH/kD = 1.04-1.08) indicate considerable nucleophilic participation by solvent in the transition state. 2,4,6-Trimethylbenzyl chloride gave kH/kD = 1.09 in 80% ethanol-water but kH/kD = 1.16 in 80% trifluoroethanol-water. 2,4,6-Tri-I-butylbenzyl chloride showed kH/kD effects of 1.13-1 .I5 in I-butyl alcohol-water and 1.15-1.16 in ethanol-water. The higher kinetic isotope effects for solvolysis of these trialkylbenzyl chlorides are discussed in terms of steric hindrance to nucleophilic participation by solvent. N.m.r. chemical shifts give evidence for steric compression of the benzylic protons in 2,4,6-tri-I-butylbenzyl chlorides.Les vitesses, les parametres d'activation, et les effets isotopiques sur la cinetique du deuttrium a sont rapportis pour la solvolyse du p-m6thylbenzyle chlorure dans les systkmes trifluoroethanol 80%-eau et ethanol-eau, I-butanol-eau de compositions variables. L'effet isotopique de deuterium a dans le trifluorokthanol-eau (kH/kD = 1.14 par D) correspond approximativement a un comportement limite. Les resultats dans les autres solvants (kH/kD =

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“…In contrast, several k 40%EtOH /k 97%TFE values were reported for the proposed unimolecular S N 1 reaction or ionization pathway: the solvolyses of diphenyl chlorometane, 12,25 p-methoxybenzyl chloride, 12 cinnamyl chloride, 13 1-chloro-1-phenylethane, 23,26 4-chloro-4-methyl-2-pentyne, 22(a) trans-4-chloro-2-pentene, 22(a) tert-butyl chloride, 6(c),23 and 1-piperidinecarbonyl chloride 14 (See Table 3). Small values (k 40%EtOH / k 97%TFE = 0 to ~25) were observed due to the two solvents having the same Y Cl value, i.e., the same degree of solvent assistance for bond cleavage, but different nucleophilicity, Scheme 2 which provides a measure of the minimum extent of nucleophilic assistance.…”

Section: (G)6(h)9(a)2223mentioning

confidence: 99%

Correlation of the Rates of Solvolysis of Electron-Rich Benzoyl Chloride Using the Extended Grunwald-Wistein Equation

Oh¹,

Choi

Park³

et al. 2013

Bulletin of the Korean Chemical Society

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The solvolysis rate constants of piperonyloyl chloride (1) in 27 different solvents are well correlated with the extended Grunwald-Winstein equation, using the N T solvent nucleophilicity scale, Y Cl solvent ionizing scale, and I aromatic ring parameter with sensitivity values of 0.30 ± 0.05, 0.71 ± 0.02, and 0.60 ± 0.04 for l, m, and h, respectively. The solvent kinetic isotope effect values (SKIE, k MeOH /k MeOD and k 50%MeOD-50%D2O ) of 1.16 and 1.12 were also in accord with the values for the S N 1 mechanism and/or the dissociative S N 2 mechanism. The product selectivity values (S) for solvolysis of 1 in alcohol/water mixtures were in the range of 0.5 to 1.9, which is also consistent with the proposed unimolecular ionization mechanism.

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Solvolysis rates and deuterium isotope effects in 2,2,2-trifluoroethanol-water mixtures

Cited by 77 publications

References 0 publications

Chlorine isotope effects in the solvolysis of substituted 1-phenylethyl chlorides

Chlorine isotope effects in the solvolysis of substituted 1-phenylethyl chlorides

Sterically Hindered Aromatic Compounds. V. Solvolysis of p-Methyl-, 2,4,6-Trimethyl-, and 2,4,6-Tri-t-butylbenzyl Chloride. Effect of Solvent and α-Deuterium Substitution

Correlation of the Rates of Solvolysis of Electron-Rich Benzoyl Chloride Using the Extended Grunwald-Wistein Equation

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