Over TiO2 photocatalyst, NO2− and NH3 are simultaneously removed from water as N2 without the use of an extra reagent.

Mechanisms of the unimolecular and bimolecular isomerization of nitrile N‐oxide to isocyanate were investigated by quantum chemical calculations using the global reaction route mapping (GRRM) technique, which consists of the anharmonic downward distortion following (ADDF) and multi‐component artificial force induced reaction (AFIR) methods, which can exhaustively search reaction paths. In the unimolecular isomerization, isomerization paths of nitrile N‐oxide to isocyanate were exhaustively explored by the ADDF method. The energetically lowest path for 2,6‐dimethoxybenzonitrile oxide (Ar–CNO) isomerization was via oxazirine intermediate formation, which was the rate‐determining step with an activation free energy of 56.8 kcal mol–1. The high activation free energy indicates that the isomerization hardly proceeds as a thermal unimolecular reaction. Next, the bimolecular isomerization paths of Ar–CNO were explored for diradical addition, [3+2] and [3+3] cycloadditions, and self‐catalyzed isomerization through the AFIR method. The diradical addition was the energetically lowest path with an activation free energy of 55.4 kcal mol–1. Although the bimolecular isomerization was energetically favorable than the unimolecular isomerization, its activation free energy was still high for the reaction to proceed under thermal conditions. Exhaustive path searching for these unimolecular and bimolecular isomerizations suggest that these reactions are catalyzed by acid or base.

Temperature. -Photocatalytic reduction of nitrite in an aqueous suspension of TiO 2 in the presence of ammonia results in the formation of N 2 under irradiation of UV light at room temperature. Simultaneous removal of and NH 3 from water at room temperature is ideal from the point of view of practical application. -(KOMINAMI*, H.; KITSUI, K.; ISHIYAMA, Y.; HASHIMOTO, K.; RSC Adv. 4 (2014) 93, 51576-51579, http://dx.

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