Stereochemistry of olefin formation in cyclopentyl brosylate solvolysis

Humski, K.; Sendijarević, Vahid; Shiner, V. J.

doi:10.1021/ja00826a042

Cited by 18 publications

(9 citation statements)

References 2 publications

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“…[3]. These isotope effects are considerably larger than those observed for SN2 reactions and Leffek and KO very reasonably concluded that these reactions must involve the formation of a carbonium ion intermediate in the slow step of the reaction.…”

Section: Table 1 Maximum Secondary A-deuterium Kineticmentioning

confidence: 84%

“…The initial concentrations of the undeuterated and dideuterated auaternarv ammonium salts in the reactant were determined from the weights of the undeuterated and deuterated quaternary salts and the deuterium content of the deuterated auaternary ammonium salt. 3 The ratio of undeuterated to dideuterated benzyl phenyl sulfide was determined in a mass spectrometric analysis of the product. The fraction of reaction was determined in a gas chromatographic analysis using the internal standard technique (1 1).…”

Section: Resultsmentioning

confidence: 99%

“…tion followed an 'ionic internal nucleophilic substiisotope effects for SN reactions of primary substrates tution' mechanism involving the triple ion 'A' shown which react by way of a carbonium ion nlechanism in [3] (7,10).…”

Section: Table 1 Maximum Secondary A-deuterium Kineticmentioning

confidence: 99%

“…For example, the magnitude of the isotope effect changes significantly when (i) the leaving group is changed (3,4) and also (ii) with a shift in the ratedetermining step of a carbonium ion reaction (ref. 2, p. 137).…”

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confidence: 99%

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Isotope effects in nucleophilic substitution reactions. II. Secondary α-deuterium kinetic isotope effects: a criterion of mechanism?

Westaway¹,

Ali²

1979

Can. J. Chem.

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A very large secondary a-deuterium kinetic isotope effect of 1.179 i 0.007 (1.086 i 0.003 per a-deuterium) has been observed for the SN2 reactlon of thlophenoxide ion with benzyldimethylphenylammonium ion in D M F at 0°C. This large isotope effect which is far outside the range reported for SN2 reactions, is attributed to the fact that the extraordinarily large steric crowding around the Ca-H bonds in the substrate is reduced in the SN2 transition state. The structure of the transition state is shown to be consistent with this hypothesis.KENNETH CHARLES WESTAWAY et SYED FASAHAT ALI. Can. J. Chem. 57, 1089(1979). Dans la reaction SN2 de l'ion thiophenolate avec l'ion benzyldimethylphenylamn~oi~ium dans le D M F a O°C, on a observe un effet isotopique cinttique secondaire du deuterium en alpha qui est tres grand 1.179 + 0.007 (1.086 i 0.003 par deuterium a). Cet effet isotopique important, qui est a l'exterieur des valeurs rapportees pour des reactions SN2, peut btre attribue au fait que l'encombrement sttrique qui est particulierement important au niveau des liaisons Ca-H dans le substrat est reduit dans l'etat de transition SN2. On demontre que la structure de I'etat de transition est en accord avec cette hypothese.[Traduit par le journal]

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Section: Table 1 Maximum Secondary A-deuterium Kineticmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Table 1 Maximum Secondary A-deuterium Kineticmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Isotope effects in nucleophilic substitution reactions. II. Secondary α-deuterium kinetic isotope effects: a criterion of mechanism?

Westaway¹,

Ali²

1979

Can. J. Chem.

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“…[2] (1-6). This mechanism was suggested for two reasons, i.e., because (i) very large secondary a-deuterium kinetic isotope effects of 1.25 (1.12 per a-D) and 1.20 (1.10 per a-D) were found for the decomposition of benzyldimethylphenylammonium bromide in chloroform and acetone, respectively (3) (the maximum value expected for a secondary a-deuterium kinetic isotope effect in an $42 reaction at this time was 1.04 per a-D or 1.08 per CDz group (7)), and (ii) because the reactivity of these salts was that observed for carbocation ion SN reactions, i.e., the secondary substrate, 1-phenylethyldimethylphenylammonium bromide, reacted 22.5 times faster than the primary substrate, benzyldimethylphenylammonium bromide in chloroform.…”

Section: Introductionmentioning

confidence: 96%

Isotope effects in nucleophilic substitution reactions. V. The mechanism of the decomposition of 1-phenylethyldimethylphenylammonium halides in chloroform

Joly¹,

Westaway²

1986

Can. J. Chem.

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Secondary a and P hydrogen-deuterium kinetic isotope effects have been used together to show that the SN reaction between 1-phenylethyldimethylphenylammonium ion and bromide or iodide ion in chloroform occurs by way of an SN2 mechanism within a triple ion in spite of the fact that it reacts faster than the primary substrate, benzyldimethylphenylamrnonium bromide. The very loose transition state and steric effects in the ground state appear to be responsible for the unusually fast SN2 reactions between 1-phenylethyldimethylphenylammonium ion and halide ions in chloroform.HELEN ALMA JOLY et KENNETH CHARLES WESTAWAY. Can. J. Chem. 64, 1206Chem. 64, (1986.On a fait appel h une combinaison des effets isotopiques cinCtiques secondaires des hydrogknes et (ou) deutCriums en a ainsi qu'en p pour montrer que le mCcanisme de la rkaction SN qui se produit dans le chloroforme entre l'ion dimCthyl phCnyl-1 kthyl phCnylammonium et les ions bromure ou iodure est SN2, dans un ion triple, et ce en dCpit du fait que cette r6action soit plus rapide que celle du substrat primaire, le bromure de benzyl dimkthyl phCnylammonium. 11 semble que 1'Ctat de transition trks lsche et que les effets sttriques dans 1'6tat fondamental soient responsables pour la kaction SN2 exceptionnellement rapide des halogknures de dimCthyl phtnyl-1 Cthyl phCnylammonium dans le chloroforme.[Traduit par la revue]

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Secondary Deuterium Isotope Effects on Reactions Proceeding Through Carbocations

Sunko

Hehre

1983

Progress in Physical Organic Chemistry

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Stereochemistry of olefin formation in cyclopentyl brosylate solvolysis

Cited by 18 publications

References 2 publications

Isotope effects in nucleophilic substitution reactions. II. Secondary α-deuterium kinetic isotope effects: a criterion of mechanism?

Isotope effects in nucleophilic substitution reactions. II. Secondary α-deuterium kinetic isotope effects: a criterion of mechanism?

Isotope effects in nucleophilic substitution reactions. V. The mechanism of the decomposition of 1-phenylethyldimethylphenylammonium halides in chloroform

Secondary Deuterium Isotope Effects on Reactions Proceeding Through Carbocations

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