Studies on the Catalytic Reductive Aminolysis. IV

Abstract

R-A reaction of diethanolamine, diisopropanolamine, and N-(2-hydroxyprop yl)-ethanolamine as dialkanolamines and ammonia at around 200° in the presence of Raney nickel yielded 33% piperazine, 82% 2, 6-dimethylpiperazine, and 18% 2-methylpiperazine, respectively. Similarly, R-A reactions on N-alkyldiethanolamines (alkyl groups were methyl, ethyl, butyl and phenyl) showed greater hydrogen uptake with an increase of numbers of carbon atom in methyl, ethyl and butyl groups with the exception of the phenyl group. The reaction at 200°, besides recovering of raw material, only one or two of the hydroxyl groups in dialkknolamines were converted into amino groups and the formation of piperazine ring from alkyl groups composed of methyl, ethyl, butyl, and phenyl groups was 15%, 23%, 14%, and 16%, respectively. The R-A reaction of N-methyldiethanolamine and N-butyldiethanolamine at 250° decreased the amount of recovered raw material and the yield of products having higher boiling point than the reaction at 200° but the yield of products having lower boiliug point was increased. However, it was considered that there was no particular increase in yield of piperazine. The amount of hydrogen absorption was increased accordingly.