Carboxylic acids can be synthesized by reacting olefins with carbon monoxide and water in the presence of a variety of transition transition metal catalysts:(1) Metals which have been employed as catalysts for this reaction include nickel, as first reported [1] by Reppe for the synthesis of acrylic and propionic acids from acetylene and ethylene, cobalt, iron, rhodium, ruthenium, palladium, and platinum [2]. The earlier studies of this reaction employed nickel, cobalt, and iron catalysts and required rather severe operating conditions, viz., 200-300 atm and 200-300°C. More recently the use of rhodium [3], iridium [4], platinum [5], palladium [6], and pyridine-promoted cobalt [7] catalysts has been reported. These latter systems all function at relatively mild reaction conditions (see Table 1).