Hydroxylamine: an overseen intermediate that brings into question nitrogen selectivity in metal-catalyzed nitrate and nitrite reduction

In decades of nitrate and nitrite hydrogenation research, nitrite, ammonia, and nitrogen gas were assumed to be the only relevant products. However, we have discovered hydroxylamine on several metal catalysts under various reaction conditions using a simple derivatization strategy based on the oximation of benzaldehyde with hydroxylamine. This previously overlooked intermediate challenges pervasive assumptions of nitrogen gas selectivity and compels a reexamination of the reaction mechanism. Additionally, the hydroxylamine presence represents a major setback for the application of catalytic nitrate and nitrite reduction in drinking water purification.