PSEUDOHALOGEN CHEMISTRY-VII. ADDITION OF THIOCYANOGEN TO ALKYNES
Thiocyanogen does not react with simple alkynes under heterolytic conditions in benzene at 20-25 deg C.Under homolytic conditions, addition occurs readily giving mixtures of E- and Z-dithiocyanatoalkenes with high E:Z ratios; prolonged treatment with excess reagent also leads to mixtures of the dithiocyanatoalkenes but usually with lower E:Z ratios.A radical-chain mechanism, involving preferential anti-addition of thiocyanogen in an initial kinetically-controlled reaction and subsequent thermodynamically-controlled isomerisation of the adducts, is proposed.The influence of substituents on the reaction rates and product ratios is discussed in terms of their steric effects.
Guy, R. G.,Cousins, S.,Farmer, D. M.,Henderson, A. D.,Wilson, C. L.
p. 1839 - 1842
(2007/10/02)
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