Kinetics and Mechanism of Reactions of Benzhydryl Chlorides with Anilines

Chang, Saemin; Koh, Han Joong; Lee, Bon-Su; Lee, Ikchoon

doi:10.1021/jo00129a016

Cited by 25 publications

(9 citation statements)

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“…Recent work on solvolyses of 9 and related compounds 32 indicates the possibility of a concerted substitution mechanism, with a kinetic solvent isotope effect (MeOH/ MeOD) of 2.3. 36 The kinetic solvent isotope effect has been noted as a disappointing criterium of the mechanism, 37 but in a recent study of an S N 2(P) solvolysis of (PhO) 2 POCl, we found an l value (eq 1) of ca. 36 The kinetic solvent isotope effect has been noted as a disappointing criterium of the mechanism, 37 but in a recent study of an S N 2(P) solvolysis of (PhO) 2 POCl, we found an l value (eq 1) of ca.…”

Section: Discussionmentioning

confidence: 80%

Solvolytic Reactions in Fluorinated Alcohols. Role of Nucleophilic and Other Solvation Effects

1998

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Rate constants and products for solvolyses of chlorodiphenylmethane (Ph 2 CHCl) and p-methoxybenzyl chloride in 2,2,2-trifluoroethanol (TFE)/water and TFE/ethanol are reported, along with additional kinetic data for solvolyses of tert-butyl and other alkyl halides (RX) in 97% w/w TFE/ water and in 97% w/w hexafluoropropan-2-ol/water (HFIP). Results are discussed in terms of the solvent ionizing power (Y) and the solvent nucleophilicity (N), and contributions from other solvation effects are considered. Comparisons with other S N 1 solvolyses show that solvolyses of Ph 2 CHCl in TFE mixtures are unexpectedly fast, but product ratios are unexceptional. An additional solvation effect influences solvolyses leading to delocalized cations, and a delocalized cationic transition state for concerted elimination may explain the recent results of Takeuchi et al., (J. Org. Chem. 1997, 62, 4904) without the need to postulate additional specific solvation effects for adamantyl systems, such as Bronsted-base solvation of Rand -hydrogen atoms; concerted elimination may occur because simple tertiary alkyl cations are too unstable to form in predominantly aqueous media. Iodide/bromide and bromide/chloride rate ratios are very similar for 1-adamantyl halides and corresponding solvolyses of tert-butyl halides; these ratios decrease in the order aq EtOH > TFE > HFIP, as expected for an electrophilic solvation effect (this effect can readily be incorporated into Y values). From kinetic data for a series of tertiary alkyl chlorides in 97% TFE/water, it is shown that the susceptibility of rates of solvolyses of RCl to N decreases with an increase in steric hindrance or with an increase in charge stabilization. Also, the small kinetic solvent isotope effects for typical solvolyses (e.g., methyl tosylate) indicate that nucleophilic attack lags behind heterolysis of the C-X bond. 4654

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Section: Discussionmentioning

confidence: 80%

Solvolytic Reactions in Fluorinated Alcohols. Role of Nucleophilic and Other Solvation Effects

1998

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“…18 The anilinolyses of Y-benzhydryl chlorides [YC 6 H 4 CH(C 6 H 5 )Cl] in methanol also exhibited the change of the sign of ρ X depending on Y substituents (min; ρ X = -0.76 with Y = 4-NO 2 and max; ρ X = +0.95 with Y = 4-CH 3 ). 19 The positive ρ X values of both reaction systems were interpreted in terms of a TS structure in which nearly complete bond formation between the nucleophile and cation formed in an ion-pair pre-equilibrium is coupled with a TS imbalance phenomenon, advocated by Jencks and Bernasconi.…”

Section: Gmentioning

confidence: 99%

Kinetics and Mechanism of the Pyridinolysis of Bis(2,6-dimethylphenyl) Chlorophosphate in Acetonitrile

Barai¹,

Lee²

2011

Bulletin of the Korean Chemical Society

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The nucleophilic substitution reactions of bis(2,6-dimethylphenyl) chlorophosphate (5), containing the four ortho-methyl substituents, with X-pyridines are investigated kinetically in MeCN at 65.0 o C. The free energy correlations for substituent X variations in the nucleophiles exhibit biphasic concave upwards with a breakpoint at a X = 3-Cl. Unusual positive ρ X (= +5.40) and negative β X (= -0.83) values are obtained with the weakly basic pyridines. The pyridinolysis rate of 5 is hundreds times slower compared to that of bis(phenyl) chlorophosphate because of the steric hindrance of the four ortho-methyl substituents in the two phenyl rings. Ion-pair mechanism is proposed and positive ρ X and negative β X values are substantiated by an imbalance of the transition state.

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“…Other reagents were commercially available. Products 4a [19], 4b [20], 4c [20], 4d [21], 4e [22], 7a [23], 7b [24], 7c [25], 7d [26], 7e [27], 7f [28], 7g [29], 9a [30], 9b [31], 9c [31], 9d [32], and 9e [9] are known.…”

Section: Generalmentioning

confidence: 99%

Rhodium-catalyzed addition of arylboron compounds to nitriles, ketones, and imines

Ueura

Miyamura

Satoh

et al. 2006

Journal of Organometallic Chemistry

111

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Kinetics and Mechanism of Reactions of Benzhydryl Chlorides with Anilines

Cited by 25 publications

References 0 publications

Solvolytic Reactions in Fluorinated Alcohols. Role of Nucleophilic and Other Solvation Effects

Solvolytic Reactions in Fluorinated Alcohols. Role of Nucleophilic and Other Solvation Effects

Kinetics and Mechanism of the Pyridinolysis of Bis(2,6-dimethylphenyl) Chlorophosphate in Acetonitrile

Rhodium-catalyzed addition of arylboron compounds to nitriles, ketones, and imines

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