Chlorination and chloroiodination of acetylenes with copper(II) chloride
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 6,p. 676-680
- https://doi.org/10.1039/p19770000676
Abstract
Reactions of acetylenes (RCCR′; R and/or R′= H, alkyl, or phenyl)(1), with copper(II) chloride–lithium chloride in acetonitrile give the corresponding E-dichloroalkenes in good yields except in the case of (1; R = Ph, R′= But) where the Z-product is favoured. Reactions with copper(II) chloride–iodine or –potassium iodide proceed more smoothly to afford, completely regiospecifically and highly stereospecifically, E-chloroiodoalkenes in high yields. Reactions with iodine chloride also give the same compounds, but the yield and E-stereospecificity are low in comparison with those in the copper(II) chloride–iodine case. An open vinyl cation intermediate in which copper(I) co-ordinates weakly with both the double bond and the chlorine atom attached to carbon is postulated for chlorination, and a cyclic iodonium ion intermediate is proposed for chloroiodination.Keywords
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