Efficient catalytic hydration of acetonitrile to acetamide using [Os(CO)3Cl2]2

Various osmium species (e.g. Na-2[Os10C(CO)(24)], OsCl3.nH(2)O and [Os(CO)(3)Cl-2](2)) are able to activate acetonitrile towards nucleophilic attack by water to give acetamide. The most efficient catalyst appears to be [Os(CO)(3)Cl-2](2), which gives good yields of acetamide by working in air at 76 degreesC. 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)(3)Cl-2](2) is much less efficient than its osmium analogue due to its easy conversion in [Ru(CO)(2)Cl-2(CH3CN)(2)] under the reaction conditions. (C) 2003 Elsevier Science B.V. All rights reserved.