التفاصيل البيبلوغرافية
| العنوان: |
Calculated Third Order Rate Constants for Interpreting the Mechanisms of Hydrolyses of Chloroformates, Carboxylic Acid Halides, Sulfonyl Chlorides and Phosphorochloridates. |
| المؤلفون: |
Bentley, T. William |
| المصدر: |
International Journal of Molecular Sciences; 2015, Vol. 16 Issue 5, p10601-10623, 23p, 7 Diagrams, 4 Charts, 7 Graphs |
| مصطلحات موضوعية: |
SULFONYL chlorides, CHLOROFORM, CARBOXYLIC acids, HYDROLYSIS, HALIDES, SOLVOLYSIS, GRUNWALD-Winstein equation, PHOSPHOROUS acid |
| مستخلص: |
Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides) exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1) to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels--an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3) are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides). Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride). [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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