RUTHENIUM CATALYZED-REACTIONS OF ETHYLENE-GLYCOL WITH PRIMARY AMINES - STERIC FACTORS AND SELECTIVITY CONTROL

The selectivity of reactions of ethylene glycol with primary amines in the presence of RuCl2(PPh3)3 at 120-degrees-C is highly dependent on the steric nature of the amine. Selectivity to di-amination is favored by smaller alkyl groups on the amine while large amines cleanly yield ethanolamines. This contrasts with the results obtained with secondary amines at this temperature, in which ruthenium-triphenylphosphine catalyst systems always favor mono-amination. In the case of sec-butyl amine, where almost equal amounts of mono- and di-aminated product are obtained, the selectivity can be shifted to mono-amination by the addition of excess triphenylphosphine. The steric effects seen in these reactions are consistent with standard steric parameters available from the literature.