Prediction of SN2 transition state variation by the use of More O'Ferrall plots

Harris, J. Milton; Shafer, Steven G.; Moffatt, John R.; Becker, Allyn R.

doi:10.1021/ja00506a026

Cited by 71 publications

(29 citation statements)

References 6 publications

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“…Once the actual transition state structures had been determined, the effect of changing a substituent at the a carbon could be compared with the theoretical predictions based on Thornton's reacting bond rule (50) and More O'Ferrall's energy surface (6,51). According to Thornton's rule, the overall effect of a S,2 reaction is comprised of the substituent effect on the perpendicular and the parallel vibrations of the transition state.…”

Section: Comparison Of the Experimental Results And Theoretical Predimentioning

confidence: 99%

Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of S_N2 transition states

Westaway¹,

Waszczylo²

1982

Can. J. Chem.

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Kinetic studies, secondary α-deuterium kinetic isotope effects, primary chlorine kinetic isotope effects (1), Hammett ρ values determined by changing the substituent in the nucleophile, and activation parameters have been used to determine the detailed (relative) structures of the transition states for the SN2 reactions between para-substituted benzyl chlorides and thiophenoxide ion. A rationale for the U-shaped Hammett ρ plots observed when para-substituted benzyl compounds react with negatively charged nucleophiles is also presented.

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Section: Comparison Of the Experimental Results And Theoretical Predimentioning

confidence: 99%

Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of S_N2 transition states

Westaway¹,

Waszczylo²

1982

Can. J. Chem.

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“…Although some authors 13,14 claim that leaving group effects in solvolytic reactions are not very sensitive to mechanistic changes, the consideration of these effects in nucleophilic substitution reactions has long been recognized as a useful tool in studying the reaction mechanism. 15 For SN1 reaction, a value of kF/kCl = 10 -6 -10 -7 was observed in 4-(N,N-dimethylamino)benzoyl halide solvolyses 16 and a low value of kF/kCl = 1.3 × 10 -4 was also observed for acetyl halide solvolyses in 75% acetone.…”

Section: Discussionmentioning

confidence: 99%

Correlation of the Rates of Solvolysis of Methyl Fluoroformate Using the Extended Grunwald-Winstein Equation

Lee¹,

Rhu²,

Kyong³

et al. 2009

Bulletin of the Korean Chemical Society

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The specific rates of solvolysis of methyl fluoroformate have been measured at 40.0 o C in several hydroxylic solvents. Analysis with the extended Grunwald-Winstein equation leads to sensitivities toward changes in solvent nucleophilicity (l) of 1.33 ± 0.10 and toward changes in solvent ionizing power (m) 0.73 ± 0.06. For methanolysis, a solvent deuterium isotope effect of 3.98 is compatible with the incorporation of general-base catalysis into the substitution process. For four representative solvents, studies were made at several temperatures and activation parameters determined. These observations are also compared with those previously reported for alkyl halogenoformate esters and mechanistic conclusions are drawn.

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“…Trabalhos sobre solvólise dos cloretos de benzila [40][41][42][43][44][45] mostram que a presença de um grupo receptor de elétrons no anel benzílico diminui a velocidade de reação, em relação ao substrato não substituído, enquanto que a de um grupo doador, aumenta.…”

Section: Cloretos De Arilmetilaunclassified

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

1997

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The experimental results for the 2-propanolysis of benzoyl, benzyl, benzene sulphenyl and benzene sulphonyl chlorides obtained by conductimetric technique were compared with estimates for chlorobenzene which is extremely unreactive as an electrophile. We thus obtained the following reactivity sequence: PhSCl>PhCOCl>PhSO 2 Cl>PhCH 2 Cl>PhCl with rate-coefficiente ratios (in the same order): 9.5 x 10 4 : 1: 7.14 x 10 -2 : 4.7 x 10 -3 : about 10 -26 . We have discussed these results in specific terms and with the aid of general conclusions which stem from our own classification of electrophiles.Keywords: 2-propanolysis; electrophilic carbon and sulphur centres; solvolysis mechanism. ARTIGO INTRODUÇÃONo campo da substituição nucleofílica, as pesquisas relativas às reatividades de substratos que têm como centro eletrofílico o carbono saturado 1,2 , o carbono carbonílico 3,4 e o carbono aromá-tico 5 têm recebido muita atenção; entretanto, estudos comparativos entre si são raros. Algumas comparações entre as reatividades dos carbonos: aromático e saturado, carbonílico e saturado, aromático e carbonílico, aromático, heteroaromático e sistema tropílico, carbonílico e imidoílico, e de arenos coordenados e não-coordenados são descritas na literatura [6][7][8][9][10][11][12][13][14][15] . Todavia, muito pouco é conhecido acerca da reatividade do enxofre como centro eletrofílico, embora haja uma quantidade razoável de trabalhos sobre centros sulfonílicos 16 e pouco sobre centros sulfenílicos.Estudos comparativos das reatividades relativas de compostos com carbono e enxofre como centros eletrofílicos, em solvólise nucleofílica, são, ainda, desconhecidos. Assim, no presente trabalho dispensou-se atenção aos cloretos de benzenossulfenila em reações de solvólise com 2-propanol e, para comparação, foram relacionadas reações de substituição nucleofílica nos grupos carbonila e sulfonila e nos carbonos saturado e aromático.A escolha do 2-propanol para o estudo da solvólise nucleofí-lica foi baseada na facilidade para seguir as reações usando uma técnica convencional (condutimetria), no nível conveniente de velocidade de reação, na escassez de dados de sua solvólise nucleofílica e no desejo de comparar os diferentes sistemas, sem as complicações introduzidas se algum deles reagisse por um mecanismo unimolecular (S N 1). Julgou-se que isso não ocorre em 2-propanol anidro para os compostos não substituídos e muito menos para os que possuem substituintes receptores de elé-trons no anel benzênico. Julgou-se, também, que entre as classes de compostos estudados, aquelas que oferecem maiores chances de operar por um mecanismo unimolecular são os sistemas benzílico e benzoílico. Entretanto, é muito relevante o fato de ter-se constatado que, mesmo na metanólise, nem cloreto de benzila e nem de benzoíla reagiu por um mecanismo S N 1 11,17 . Escolheram-se sistemas arílicos por conveniência e porque planejou-se estender os estudos cinéticos para incluir arenos eletrofí-licos. A escolha do cloreto como nucleófugo se deveu ao fato de ele se consti...

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Prediction of SN2 transition state variation by the use of More O'Ferrall plots

Cited by 71 publications

References 6 publications

Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of S_N2 transition states

Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of S_N2 transition states

Correlation of the Rates of Solvolysis of Methyl Fluoroformate Using the Extended Grunwald-Winstein Equation

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

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Prediction of SN2 transition state variation by the use of More O'Ferrall plots

Cited by 71 publications

References 6 publications

Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of SN2 transition states

Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of SN2 transition states

Correlation of the Rates of Solvolysis of Methyl Fluoroformate Using the Extended Grunwald-Winstein Equation

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

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Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of S_N2 transition states

Isotope effects in nucleophilic substitution reactions. IV. The effect of changing a substituent at the α carbon on the structure of S_N2 transition states