Primary amines are of significant importance in the chemical industry with many products requiring the use of these compounds in their production. Although there are several possible routes for these species to be synthesised, it is the heterogeneously catalysed hydrogenation of nitriles that is most commonly used in agrichemical production chains where this research finds application. Nevertheless, as a consequence of imine derived chemistry, selectivity is a major issue associated with these reactions. Against this background the catalytic hydrogenation of nitriles by a 5% Pd/C catalyst to yield primary amines of relevance to the manufacture of agrichemicals has been explored. In this instance <i>p</i>-hydroxybenzyl cyanide has been selected as a model substrate suitable to probe this catalytic process and allow valuable insight applicable to more complex systems to be gleaned. Initially very poor, the selectivity towards the desired product was improved through application of an acid additive and the tuning of operational parameters linked to the hydrogen availability in the system. The completely selective production of tyramine has now been achieved as confirmed by both high performance liquid chromatography analysis and proton nuclear magnetic resonance spectroscopy. Moreover, also considered was the potential for a detrimental hydrogenolysis step - cleavage of the amine functionality. Although not active in this particular study, advantageous information regarding this process was obtained.

Selective liquid phase hydrogenation of <i>p</i>-hydroxybenzyl cyanide over a supported Pd catalyst

256th National Meeting (2018)

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Selective liquid phase hydrogenation of p-hydroxybenzyl cyanide over a supported Pd catalyst