Efficient catalytic hydration of acetonitrile to acetamide using [Os(CO)3CI2]2

Various osmium species (e.g. Na2[Os10C(CO) 24], OsCl3·nH2O and [Os(CO) 3Cl2]2) are able to activate acetonitrile towards nucleophilic attack by water to give acetamide. The most efficient catalyst appears to be [Os(CO)3Cl2]2, which gives good yields of acetamide by working in air at 76 °C. An increase of the quantity of water has a positive effect on yields, a plateau being reached with a molar ratio H2O:CH3CN of about 7.3:1. The catalytic activity of the osmium species decreases with prolonged heating, due to the progressive partial decarbonylation of fac-tricarbonylosmium(II) species. The complex [Ru(CO)3Cl2]2 is much less efficient than its osmium analogue due to its easy conversion in [Ru(CO) 2Cl2(CH3CN)2] under the reaction conditions.