Extended charge delocalization to 4‐phenoxy substituent in benzhydryl solvolysis: possible contribution of non‐canonical resonance structure in the cationic transition state

Liu, Kwang‐Ting; Chuang, Chih‐Shiow; Jin, Bih‐Yaw

doi:10.1002/poc.439

Cited by 4 publications

(2 citation statements)

References 29 publications

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“…Nucleofugalities of chloride and bromide in different solvents : Solvolysis rates of benzhydrylium chlorides and bromides have been investigated in a manifold of solvents,7, 11, 12 and the corresponding rate constants are given in the Supporting Information. As depicted in Figure 1, the isopropanolysis rate constants of benzhydrylium chlorides, as well as the corresponding solvolysis rate constants in 90 % aqueous methanol (90M) and 70 % aqueous acetone (70A), correlate well with the corresponding electrofugality parameters E f reported in the preceding article 10.…”

Section: Resultsmentioning

confidence: 99%

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How Fast Do RX Bonds Ionize? A Semiquantitative Approach

Denegri

Ofial

Jurić

et al. 2006

Chemistry A European J

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The correlation equation log k(25 degrees C) = sf(Nf + Ef), where sf and Nf are nucleofuge-specific parameters referring to leaving group/solvent combinations and Ef are electrofuge-specific parameters referring to the incipient carbocation R+, are used to predict ionization rate constants of alkyl derivatives R--X. We show how to employ the Ef parameters of reference electrofuges and the sf and Nf parameters of reference nucleofuges reported in the preceding article for determining further sf, Nf, and Ef parameters. Since sf is usually close to 1.0, one comes to the semiquantitative rule that at 25 degrees C, compounds R--X for which Nf + Ef>-2 will solvolyze with half-lives of less than a minute, while the solvolysis half-lives will exceed 1 month if Nf + Ef<-6.5.

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Section: Resultsmentioning

confidence: 99%

“…methanol (90M), 70 % aq. acetone (70A), and isopropanol7, 11, 12 with the electrofugalities E f of the benzhydrylium ions from ref. 10.…”

Section: Resultsmentioning

confidence: 99%

How Fast Do RX Bonds Ionize? A Semiquantitative Approach

Denegri

Ofial

Jurić

et al. 2006

Chemistry A European J

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Kinetics of the Solvolyses of Benzhydryl Derivatives: Basis for the Construction of a Comprehensive Nucleofugality Scale

Denegri

Streiter

Jurić

et al. 2006

Chemistry A European J

100

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A series of 21 benzhydrylium ions (diarylmethylium ions) are proposed as reference electrofuges for the development of a general nucleofugality scale, where nucleofugality refers to a combination of leaving group and solvent. A total of 167 solvolysis rate constants of benzhydrylium tosylates, bromides, chlorides, trifluoroacetates, 3,5‐dinitrobenzoates, and 4‐nitrobenzoates, two‐thirds of which have been determined during this work, were subjected to a least‐squares fit according to the correlation equation log k25 °C = sf(Nf + Ef), where sf and Nf are nucleofuge‐specific parameters and Ef is an electrofuge‐specific parameter. Although nucleofuges and electrofuges characterized in this way cover more than 12 orders of magnitude, a single set of the parameters, namely sf, Nf, and Ef, is sufficient to calculate the solvolysis rate constants at 25 °C with an accuracy of ±16 %. Because sf≈1 for all nucleofuges, that is, leaving group/solvent combinations, studied so far, qualitative discussions of nucleofugality can be based on Nf.

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Correlation of the rates of solvolysis of 2‐furancarbonyl chloride and three naphthoyl chlorides

D’Souza

Boggs

Kevill

2006

J of Physical Organic Chem

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The correlations of the specific rates of solvolysis of the title compounds using extended forms of the Grunwald–Winstein equation are consistent with the overall picture which is emerging for acyl chloride solvolyses, with competing addition–elimination (with rate‐determining addition) and ionization (assisted by nucleophilic solvation) pathways. Except in the more ionizing solvents of low nucleophilicity, 2‐furancarbonyl chloride follows the addition–elimination pathway, in contrast to 2‐thiophenecarbonyl chloride. Except in solvents of highest nucleophilicity and low ionizing power, the solvolyses of the naphthoyl chlorides (1‐naphthoyl, 2‐naphthoyl and 6‐methyl‐2‐naphthoyl) all favor the ionization pathway. In the correlation of the 1‐naphthoyl chloride solvolyses, there is a slight improvement when a term governed by the sensitivity to changes in the aromatic ring parameter (hI) is incorporated; this can be associated with a rather minor steric hindrance involving the peri‐hydrogen. Copyright © 2006 John Wiley & Sons, Ltd.

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Extended charge delocalization to 4‐phenoxy substituent in benzhydryl solvolysis: possible contribution of non‐canonical resonance structure in the cationic transition state

Cited by 4 publications

References 29 publications

How Fast Do RX Bonds Ionize? A Semiquantitative Approach

How Fast Do RX Bonds Ionize? A Semiquantitative Approach

Kinetics of the Solvolyses of Benzhydryl Derivatives: Basis for the Construction of a Comprehensive Nucleofugality Scale

Correlation of the rates of solvolysis of 2‐furancarbonyl chloride and three naphthoyl chlorides

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