In a previous paper it was shown that aldehydes3 could not be reduced to alcohols with hydrogen and platinum-oxide platinum black unless some promoter such as a ferrous salt was present. As these promoters for the reduction of aldehydes are poisons toward the reduction of olefins, the study of the reduction of alp unsaturated aldehydesJ4 in particular cinnamic aldehyde and citral, resulted in the discovery that by using a ferrous salt, ...