Solvolysis-decomposition of 1-adamantyl chloroformate: evidence for ion pair return in 1-adamantyl chloride solvolysis

Kevill, Dennis N.; Kyong, Jin Burm; Weitl, Frederick L.

doi:10.1021/jo00301a019

Cited by 63 publications

(89 citation statements)

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“…The ionization pathway with solvolysis-decomposition is the only one operating for solvolyses of 1-adamantyl chloroformate, with loss of CO 2 leading to the relatively stable1-adamantyl cation, which can be captured by simultaneously formed chloride ion or solvent [23]. The lack of any dependence on N T is consistent with the positive charge at the transition state residing predominantly at the bridgehead carbon of the developing 1-adamantyl cation.…”

Section: Introductionmentioning

confidence: 81%

“…One might have anticipated, with the bromide salt, a perturbation due to chloride/bromide exchange but this does not seem to occur to any appreciable extent and the slight increases are very well explained in terms of a modest salt effect upon the solvolysis. Additions of chloride, bromide, or iodide, as the tetrabutylammonium salts, to the ethanolysis of 1-adamantyl chloroformate had essentially identical small effects (13% increase at 0.1 M salt), again independent of the identity of the anion [23]. As with the n-propyl chloroformate solvolysis, this was taken to indicate that there was no superimposed initial halide exchange.…”

Section: Methodsmentioning

confidence: 99%

“…Solvents were purified and the kinetic runs carried out as previously described [23]. The n-propyl chloroformate (Aldrich, 98%) was used as received.…”

Section: Acknowledgementsmentioning

confidence: 99%

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Application of the Extended Grunwald-Winstein Equation to Solvolyses of n-Propyl Chloroformate

Kyong

Won

Kevill

2005

IJMS

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Application of the extended Grunwald-Winstein equation to solvolyses of n-propyl chloroformate in a variety of pure and binary solvents indicates an addition-elimination pathway in the majority of the solvents but an ionization pathway in the solvents of highest ionizing power and lowest nucleophilicity. For methanolysis, a solvent deuterium isotope effect of 2.17 is compatible with the incorporation of general-base catalysis into the substitution process. Activation parameters are consistent with the duality of mechanism. Very modest positive salt effects are observed on adding chloride or bromide salts to the ethanolysis.

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Section: Introductionmentioning

confidence: 81%

Section: Methodsmentioning

confidence: 99%

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Application of the Extended Grunwald-Winstein Equation to Solvolyses of n-Propyl Chloroformate

Kyong

Won

Kevill

2005

IJMS

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“…For the tertiary 1-adamantyl chloroformate, the ionization pathway was dominant in all solvents and only in 100% ethanol was a trace of the mixed carbonate, presumably from an addition-elimination reaction, detected [7]. For phenyl chloroformate the addition-elimination pathway was observed over the full range of solvents [8].…”

Section: Methodsmentioning

confidence: 94%

Rate and Product Studies of Solvolyses of Benzyl Fluoroformate

Kyong

Ryu

Kevill

2006

IJMS

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Abstract:The specific rates of solvolysis of benzyl fluoroformate have been measured in several hydroxylic solvents at 25.0 °C. For methanolysis, the solvent deuterium isotope effect and activation parameters were determined and activation parameters were also determined for solvolyses in ethanol and 80% ethanol. For several of the binary hydroxylic solvents, measurement of product ratios allowed selectivity values to be determined. An extended Grunwald-Winstein treatment of the data led to sensitivities to changes in solvent nucleophilicity and ionizing power. Comparison with previously determined specific rates for solvolysis of the chloroformate gave fluorine/chlorine rate ratios greater than unity. All of the determinations made were consistent with an addition-elimination (associationdissociation) mechanism, with addition rate-determining.

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“…12 Replacement of the tertbutyl group by the bridgehead 1-adamantyl group gives a more stable tertiary chloroformate ester and kinetic and product studies of its decomposition in inert solvents 13 and of its solvolyses 14 indicate an ionization-fragmentation mechanism in a wide range of solvents. Only in 100% ethanol was a small amount of the dicarbonate formed by attack of the solvent at the acyl carbon observed.…”

mentioning

confidence: 99%

Kinetic Studies of the Solvolyses of 2,2,2-Trichloro-1,1-Dimethylethyl Chloroformate

Koh

Kang²,

Kevill³

2010

Bulletin of the Korean Chemical Society

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The rate constants of solvolyses of 2,2,2-trichloro-1,1-dimethylethyl chloroformate (I) in 33 solvents can be well correlated using the extended Grunwald-Winstein equation, with incorporation of the NT solvent nucleophilicity scale and the YCl solvent ionizing scale, with sensitivities towards changes in the scale having values of 1.42 ± 0.09 for l and 0.39 ± 0.05 for m, respectively. The activation enthalpies are ∆H ≠ = 12.3 to 14.5 kcal·mol -1 and the activation entropies are -28.2 to -35.5 cal·mol -1 ·K -1 , consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.14 in MeOH/MeOD is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.

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Solvolysis-decomposition of 1-adamantyl chloroformate: evidence for ion pair return in 1-adamantyl chloride solvolysis

Cited by 63 publications

References 0 publications

Application of the Extended Grunwald-Winstein Equation to Solvolyses of n-Propyl Chloroformate

Application of the Extended Grunwald-Winstein Equation to Solvolyses of n-Propyl Chloroformate

Rate and Product Studies of Solvolyses of Benzyl Fluoroformate

Kinetic Studies of the Solvolyses of 2,2,2-Trichloro-1,1-Dimethylethyl Chloroformate

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