The reactivity of tetrahydroquinoline, benzylamine and bibenzyl with supercritical water

Abstract

An examination of the reactions of 1,2,3,4-tetrahydroquinoline, benzylamine and bibenzyl with supercritical water was made since water has been found to be effective as the solvent in the supercritical fluid extraction of coal. Also these model compounds contain functional groups thought to be present in coal or to be formed during liquefaction reactions. In addition, a brief examination of the pyrolyses of these compounds was made to better define the effects of the supercritical water. It was found that initially tetrahydroquinoline lost hydrogen, then reacted similarly to quinoline in the presence of a hydrogen donor. Benzylamine, thought to be similar to an intermediate formed from the isoquinoline-supercritical water reaction, reacted rapidly forming the most abundant product, toluene, at a constant yield in all conditions run. The second major product, benzene, formed more slowly apparently by oxidation of the benzylic carbon, as evidenced by the presence of the intermediates, benzyl alcohol and benzaldehyde. Thus, benzylamine reacts by two major pathways leading to these products. Bibenzyl appears to pyrolyse and to react with supercritical water at about the same rate, both reactions produced about the same yield of the most abundant products, toluene and stilbene. However, since benzene is not a major product in the latter reaction, it appears that the presence of nitrogen is necessary for the oxidation sequence of the benzylic carbon to occur.