Employing Ammonia for the Synthesis of Primary Amines: Recent Achievements over Heterogeneous Catalysts

Primary amines represent highly privileged chemicals for synthesis of polymers, pharmaceuticals, agrochemicals, coatings, etc. Consequently, the development of efficient and green methodologies for the production of primary amines are of great importance in chemical industry. Owing to the advantages of low cost and ease in availability, ammonia is considered as a feasible nitrogen source for synthesis of N-containing compounds. Thus, the efficient transformation of ammonia into primary amines has received much attention. In this review, the commonly applied synthetic routes to produce primary amines from ammonia were summarized, including the reductive amination of carbonyl compounds, the hydrogen transfer amination of alcohols, the hydroamination of olefins and the arylation with ammonia, in which the catalytic performance of the recent heterogeneous catalysts is discussed. Additionally, various strategies to modulate the surface properties of catalysts are outlined in conjunction with the analysis of reaction mechanism. Particularly, the amination of the biomass-derived substrates is highlighted, which could provide competitive advantages in chemical industry and stimulate the development of sustainable catalysis in the future. Ultimately, perspectives into the challenges and opportunities for synthesis of primary amines with ammonia as N-resource are discussed.