Rearrangements Concerted with Fragmentation of Cyclopropylmethoxychlorocarbene and Cyclobutoxychlorocarbene in Hydrocarbon Solvents and Ar Matrices
- 19 June 2004
- journal article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 126 (27) , 8466-8476
- https://doi.org/10.1021/ja049421x
Abstract
Fragmentations of cyclopropylmethoxychlorocarbene (6) and cyclobutoxychlorocarbene (10) lead to rearrangments that afford mixtures of cyclopropylmethyl chloride (7), cyclobutyl chloride (8), and 3-butenyl chloride (9). Isotopic substitution studies show that these rearrangments are accompanied by partial exchange of the methylene groups within 6 and 10. Surprisingly, these processes that are typical of carbocations persist in hydrocarbon solvents such as pentane and cyclohexane-d12. Quantum chemical calculations reveal that the cis-conformers of the incipient oxychlorocarbenes C4H7OC̈Cl decay to C4H7Cl + CO via transient hydrogen bonded C4H7δ+···Clδ- complexes which possess significant ion pair character, even in the gas phase or in nonpolar solvents. In contrast to benzyloxychlorocarbene, no free radicals are formed upon generation or photolysis of 6 or 10 in Ar matrixes, although acid chlorides (the recombination products of these radical pairs) are observed. The IR spectra obtained in these experiments show the presence of several conformers of the two C4H7OC̈Cl.Keywords
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