Hydration of terminal alkynes on Nafion film in supercritical carbon dioxide

To find out the conditions for mild hydration of carbon–carbon triple bonds the hydration reactions of some terminal alkynes (FcCCH, PhCCH, C5H11CCH) on the Nafion film in supercritical carbon dioxide (sc-CO2) were studied. The corresponding ketones were prepared in excellent yields. The hydration of 1-heptyne is accompanied by the isomerization of the terminal carbon–carbon triple bond into the internal one under acidic heterogeneous catalysis.

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► Nafion film hydrates terminal alkynes RCCH (RFc, Ph, C5H11) in sc-CO2 under mild conditions to give the respective ketones in excellent yields.
► The ecological compatibility and easy isolation of the reaction products are obvious advantages of this catalytic system.
► The terminal carbon–carbon triple bond in hept-1-yne was shown to migrate into the internal position under the acid heterogeneous catalysis conditions.