Hydration of Alkynes by a PtCl ₄ −CO Catalyst

Treatment of PtCl(4) with CO at 40-110 degrees C forms a powerful alkyne hydration catalyst that operates both under homogeneous conditions in wet THF and under phase-transfer conditions in (CHCl(2))(2)/H(2)O in the presence of tricaprylmethylammonium chloride (Aliquat 336). Complex HPtCl(CO)(2) is regarded as the active hydration catalyst. It is assumed to be formed by initial transformation of PtCl(4) to H(2)[Pt(3)(CO)(6)](n) (n = 5, 6) followed by reaction with HCl (generated by decomposition of the starting platinum salt).