Equilibrium Conditions for Amination of Alcohols and Carbonyl Compounds

Abstract

The influence of pressure, temperature, and initial composition of the mixture on the equilibrium content of primary, secondary, and tertiary amines and unsaturated compounds was calculated for the reductive amination of ethanol, acetone, butyraldehyde, and cyclohexanone. Requirements of the world market were respected in choosing suitable process conditions.Lower aliphatic amines, with the exception of methylamines, are commonly prepared by so-called reductive amination of alcohols or compounds containing the carbonyl group. In this manner ethylamines are produced from ethanol or acetaldehyde, isopropylamine from acetone or isopropylalcohol, butylamines from butanol or butyraldehyde, and cyclohexylamine from cyclohexanol or from a cyclohexanonecyclohexanol mixture. The reaction is catalyzed by metals such as nickel, copper, or platinum. Where the starting material is a carbonyl compound, the rate is limited by the hydrogenation of itermediary imine:In reductive amination of alcohol the reaction rate is limited by dehydrogenation of the starting alcohol (Aonuma, 1962; Pasek and Richter, 1969). On the surfaces of metal catalysts at temperatures of 50-250°C , the reaction of alcohol with ammonia is represented by a series of reversible reactions:

Solvent Influence on Rates and Mechanisms

“…In a study of the effects of temperature pressure, and starting composition on the rate of hydrogenative amination of acetone and isopropyl alcohol over nickel catalyst, it was found [515], that for the acetone reaction hydrogenation of the amine was the rate determining step; while for the isopropyl alcohol its dehydrogenation, which has a high activation energy, limited the rate.…”

Effect of Re promoter on the structure and catalytic performance of Ni–Re/Al2O3 catalysts for the reductive amination of monoethanolamine

“…[1][2][3][4] The reductive amination method has gained increasing interest since it constitutes a green economy route for the synthesis of ethylene amines. [5][6][7][8][9][10][11][12][13][14] In the reductive amination process, ethylene amines are synthesized by contacting MEA and ammonia under hydrogen atmosphere in the presence of hydrogenation-dehydrogenation metal catalysts. The reaction pathways for the transformation of MEA to ethylene amines on a metal catalyst are postulated as follows: rstly, dehydrogenation of MEA to 2-aminoacetaldehyde; secondly, condensation with ammonia or an amine to form imine; lastly, hydrogenation of imine to amine.…”

N-alkylation of amines with alcohols over alumina-entrapped Ag catalysts using the “borrowing hydrogen” methodology

“…However, this method is severely limited by the availability of the corresponding olefin and the electrophilic character of the nitrogen reagent. Another promising protocol is the alkylation of amines by alcohols using a reaction sequence that has been variously termed ''hydrogen autotransfer,'' ''borrowing hydrogen mechanism'' or ''self-supply system for active hydrogen'' [7][8][9][10][11][12].…”