Kinetic solvent isotope effect, solvent reorganization, and the SN1–SN2 mechanism

Autor:	S. E. Sugamori, R. E. Robertson, L. Treindl
Rok vydání:	1969
Předmět:	Chemistry Organic Chemistry Inorganic chemistry Halide Ether General Chemistry Chloride Heat capacity Catalysis Solvent chemistry.chemical_compound Kinetic isotope effect medicine SN2 reaction Solvolysis medicine.drug
Zdroj:	Canadian Journal of Chemistry. 47:3397-3404
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v69-563
Popis:	The temperature dependence of the rates of solvolysis have been determined in D2O for t-butyl chloride, 2,2-dibromopropane, 2-bromo-2-chloropropane, and 2-chloro-2-methyl propyl methyl ether, and corresponding values of ΔH≠, ΔS≠, and ΔCp≠ are derived. Values of ΔH≠ and ΔS≠ from the solvolysis of seven other halides and two benzenesulfonates have been estimated from rate determinations at two temperatures in D2O.A comparison of these values with terms from corresponding experiments in H2O provides values of δIΔG≠, δIΔH≠, and δIΔS≠ characterizing the kinetic solvent isotope effect.While δIΔG≠ appears to have about the same value for a wide range of halides of different structure irrespective of the probable mechanism of reaction, systematic differences in δIΔH≠ and δIΔS≠ differentiate those reacting by an SN2 mechanism from those reacting by an SN1 mechanism. This difference is in the direction suggesting a loosening of solvent structure in the activation process in agreement with indications obtained from the corresponding values of the heat capacity of activation.
Databáze:	OpenAIRE
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