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Updated: Aug 3, 2025

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid
Published on: November 15, 2017
An Efficient Continuous Flow Synthesis for the Preparation of N-Arylhydroxylamines: Via a DMAP-Mediated Hydrogenation
Jianli Chen1,2, Xinyu Lin2, Feng Xu3
1College of New Materials Engineering, Jiaxing Nanhu University, Jiaxing 314000, China.
Abstract:
The selective hydrogenation of nitroarenes to N-arylhydroxylamines is an important synthetic process in the chemical industry. It is commonly accomplished by using heterogeneous catalytic systems that contain inhibitors, such as DMSO. Herein, DMAP has been identified as a unique additive for increasing hydrogenation activity and product selectivity (up to >99%) under mild conditions in the Pt/C-catalyzed process. Continuous-flow technology has been explored as an efficient approach toward achieving the selective hydrogenation of nitroarenes to N-arylhydroxylamines. The present flow protocol was applied for a vast substrate scope and was found to be compatible with a wide range of functional groups, such as electron-donating groups, carbonyl, and various halogens. Further studies were attempted to show that the improvement in the catalytic activity and selectivity benefited from the dual functions of DMAP; namely, the heterolytic H2 cleavage and competitive adsorption.
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