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Thermal unimolecular decomposition of bicyclopropyl and deuterated analogues: infrared photoactivation as a diagnostic tool in mechanistic organic chemistry

Journal Article · · J. Org. Chem.; (United States)
DOI:https://doi.org/10.1021/jo00146a006· OSTI ID:6347381

The infrared photochemistry of bicyclopropyl yields product mixtures that are not easily rationalized on the basis of the mechanistic scheme suggested by previous pyrolysis work. As a result of this inconsistency the thermal chemistry of bicyclopropyl and analogues deuterated specifically on one ring has been reexamined. A significant new reaction channel involving the chemically activated decomposition of cyclohexene to ethylene and butadiene has been demonstrated. Evidence for the involvement of chemically activated cyclohexene is as follows: (1) isotopic labeling studies implying a symmetric intermediate, (2) a pressure-dependent ratio of cyclohexene to butadiene and ethylene, (3) good agreement between experimental and calculated values for the unimolecular rate constant for retro-Diels-Alder decay of ''hot'' cyclohexene. A comprehensive mechanism for the unimolecular decay of bicyclopropyl is proposed. The important elements of this mechanism are a single first-formed 1,3 biradical common to all products and the intervention of chemical activation in the generation of several of the secondary products.

DOE Contract Number:
AC02-80ER10592
OSTI ID:
6347381
Journal Information:
J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 47:25; ISSN JOCEA
Country of Publication:
United States
Language:
English