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Beta Secondary Deuterium Kinetic Isotope Effects on the Thermal Stereomutations of 1,2-Diphenylcyclopropanes

Lisa A. Asuncion ; Department of Chemistry, Syracuse University, Syracuse, New York 13244
John E. Baldwin ; Department of Chemistry, Syracuse University, Syracuse, New York 13244


Puni tekst: engleski pdf 23.236 Kb

str. 1421-1436

preuzimanja: 208

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Sažetak

(+)-(1S,2S)-trans-1,2-Diphenylcyclopropane and (-)-(1R,2R)-trans- l,2-diphenyl-3,3-t2-cyclopropane at 234 °C interconvert reversibly with the corresponding enantiomers and css-1,2-diphenyl cyclopropanes. For the unlabeled trans isomer, the ratio of rate constants for one-center epimerization (k\) and two-center turnover (&12) was found to be 1.1. A small normal k^Jk-Q effect, 3% per deuterium, was observed for the rate constant for one-center epimerization (k1); a substantial normal k-^lk-Q effect, 17% per deuterium, was observed for the rate constant for two-center turnover (k^). Thus different transition structures, presumably EF and EE 1,3-diphenyltrimethylene diradicals, dominate the two sorts of stereomutations.

Ključne riječi

Hrčak ID:

135980

URI

https://hrcak.srce.hr/135980

Posjeta: 455 *