Synthetic Studies of Cobalt Carbonyl by Noble Metal Catalysts. II. The Investigation of Reaction Conditions

The reaction conditions of cobalt carbonylation catalyzed by palladium have been investigated. Polar solvents have, with some exceptions, been shown to be superior to nonpolar solvents. The fact that the total pressure of synthesis gas and the partial pressure of hydrogen, especially the latter, have a great effect on the initiation temperature of reaction suggests that the presence of hydrogen is very important in the present reaction. The low reactivity and poor yield in the reactions of Raney cobalt indicate that a low-valency intermediate in the course of the cobalt-carbonylation reaction of cobaltous compounds may be somewhat different from the Raney-type Co(0). The initial step of the reaction seems to be affected only a little by various additives e. g., water, triphenyl phosphine, lead naphthenate, and sodium hydroxide. The data previously available suggest that a palladium catalyst may primarily promote the reduction of Co (II) to Co(0) by activating hydrogen. The test of the lifetime of a palladium-on-carbon catalyst for a month indicates that there is no apparent decrease in the catalytic activity within this period.