Reductive Amination of Furfural and Hydrogenation of Furonitrile

Amines are widely used in the manufacture of pharmaceuticals, agricultural chemicals, polymers, and surfactants. However, the majority of amines today are produced via petrochemical means. Thus, there is an environmental and economic driving force to produce amines from renewable resources, such as biomass. Ammonia is the ideal choice for a nitrogen source, as it is inexpensive and readily available. However, the use of ammonia produces reactive primary imines. The reactions were performed in a 150 mL stirred batch reactor under continuous stirring with a temperature controller. The reactor was purged with hydrogen, and then filled to the desired hydrogen pressure for reaction. The formation of these reactive amines is not able to detected by gas chromatography, as they will form other minor products. Another equally challenging factor in reductive amination is that primary amines are notoriously difficult to control, as they are better nucleophiles than ammonia, and easily form less valuable secondary amines. The effect of the metal used as the catalyst was tested, with pre-reduced Ruthenium being found as the best producer of the primary amine and Palladium was the best producer of the secondary amine. Other important variables in this experiment include temperature, amount of ammonia in reactor, amount of water in reactor, and pressure of hydrogen used. A key element of this reaction is the location of the reactants on either the catalyst surface or in solution and a change in temperature changes the profile of the solution. The amount of ammonia in the reactor is relevant because it is the nitrogen source. The presence of water in the reactor has an interesting effect. It forces the equilibrium in the balance between the secondary amine and primary amine toward the primary amine. However, this effect needs to be balanced with the fact that water and furfural are not miscible. Lastly, the amount of hydrogen in the reactor is needed to form the imines into amines. If this hydrogen is not present, hydrofuramide is formed and the material is lost. Further work suggested on this project include spectroscopy data of the adsorption of Furfurylamine on the catalyst surface and to obtain results at a wider range of temperatures.