Correlation of the rates of solvolysis of phenyl chloroformate

Kevill, Dennis N.; D’Souza, Malcolm J.

doi:10.1039/a701140g

Cited by 81 publications

(161 citation statements)

References 31 publications

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“…Observation of m values below unity can be considered to reflect an ionization pathway. 25 For 2,2,2-trichloro-1,1-dimethylethyl chloroformate, the values for the ratio l/m of 3.64 is similar to those previously observed for the solvolyses of n-octyl fluoroformate, 8 phenyl chloroformate, 16 methyl chloroformate, 22 and ethyl chloroformate, 23 which have been shown to solvolyze over a wide range of solvent type with the addition step of an addition-elimination pathway being rate limiting.…”

Section: Resultssupporting

confidence: 65%

“…All of the tabulated values are in the range expected for an additionelimination mechanism and they indicate a large degree of nucleophilic assistance at the transition state of the rls. 24 The lower m values (m = 0.39) for the solvolysis of 2,2,2-trichloro-1,1-dimethylethyl chloroformate, relative to n-octyl fluoroformate, 8 phenyl chloroformate, 16 methyl chloroformate, 22 and ethyl chloroformate, 23 may reflect a reduced need for solvation of the developing negative charge on the carbonyl oxygen, (see Table 3). …”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultssupporting

confidence: 65%

Section: Resultsmentioning

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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“…For 22 solvents (from Table 1, except for those mentioned immediately above) the values obtained are essentially identical to those for phenyl chloroformate [8] and for methyl [11] and ethyl chloroformates [10] over similar ranges of solvent composition (Table 4 and Figure 1). With only 6 solvent compositions within the ionization range, the number available is less than the ten considered to be a minimum for a two-term correlation [30].…”

Section: Methodssupporting

confidence: 61%

“…In the studies of the solvolyses of chloroformate esters, the aryl esters [8] solvolyze by a unit mechanism, believed to be addition-elimination (association-dissociation) over the full range of solvent type studied. There is probably general-based catalysis [20,21] to the nucleophilic attack, leading to a relatively high l value of 1.7 for phenyl chloroformate solvolyses.…”

Section: Introductionmentioning

confidence: 99%

“…Although both the N T and Y X scales are based on standard systems involving substitution reaction at an sp 3 -hybridized carbon [3,4], the scales have also been used with considerable success in the correlation analyses of solvolysis reactions of substrates which have attack at the sp 2 -hybridized carbon of acyl halides [5][6][7] and chloroformate esters [8][9][10][11][12][13][14][15], at the phosphorus atom of phosphorochloridate esters [16,17] or amides [18], and at the sulfur atom of arenesulfonyl chlorides [19].…”

Section: Introductionmentioning

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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Solvolysis ofN,N-dimethylthiocarbamoyl chloride: effect of sulfur-for-oxygen substitution upon kinetics and product partitioning

Kevill¹,

Rudolph²,

D’Souza³

2000

J. Phys. Org. Chem.

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A study of the solvolyses of N,N-dimethylcarbamoyl chloride (1) was extended to the solvolyses of N,N-dimethylthiocarbamoyl chloride (2). The specific rates of solvolysis of 2 at 0.0°C are two to three orders of magnitude greater than those for 1. Analysis of the data using the extended Grunwald-Winstein equation leads to sensitivities l and m and an l/m ratio which are lower for 2 than those previously reported for 1. Product selectivities in mixtures of water with ethanol or methanol indicate a greater preference for reaction with alcohol for 2. All observations can be rationalized in terms of the formation of a more stable carbocation from 2, leading to an earlier transition state, reduced nucleophilic solvation and the possibility of extensive progression to a free carbocation prior to product formation.

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Correlation of the rates of solvolysis of phenyl chloroformate

Cited by 81 publications

References 31 publications

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

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

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

Solvolysis ofN,N-dimethylthiocarbamoyl chloride: effect of sulfur-for-oxygen substitution upon kinetics and product partitioning

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