The reaction of alkyl isocyanide with alcohol to produce alkyl formimidate requires catalysis by metal compounds. The catalysts are classified into two groups. The first group includes metallic copper, and the oxides of copper (Cu (I) and Cu (II)), silver, and mercury, which induce the isocyanide reactions of various alcohols including saturated and unsaturated alcohols and amino-alcohol. The second group catalysts are the chlorides of copper (Cu (I)), silver, zinc, and cadmium, which cause the reactions of isocyanide only with special alcohols having strong coordinating tendencies toward the catalyst, as being exemplified by allyl alcohol and β-N,N-dimethylaminoethanol. Among these catalysts, metallic copper and copper oxides are the most effective and give the products almost quantitatively. The difference in catalyst activity between the two groups of catalysts has been explained by assuming a ternary complex consisting of the catalyst, isocyanide, and alcohol as the site of reaction.
