Photoexcited TiO2 dispersed in a de-aerated acetonitrile/2-propanol (CH3CN/2-PrOH) reaction mixture catalyzes the quick and selective reduction of 5-nitrosalicylic acid methyl ester to the corresponding aniline, an immediate precursor of the drug mesalazine. The transformation is selective also when the starting concentration of nitro compound is increased by orders of magnitude and occurs at room temperature and atmospheric pressure. The photocatalyst can be reused. The photocatalytic reaction can be carried out also under aerated conditions without any loss in selectivity and efficiency. All these factors point out the feasibility of this important synthesis under mild conditions.

中文翻译：

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TiO2 光催化选择性还原 5-硝基水杨酸乙酯：通往美沙拉秦的温和途径

分散在脱气乙腈/2-丙醇 (CH3CN/2-PrOH) 反应混合物中的光激发 TiO2 催化 5-硝基水杨酸甲酯快速选择性还原为相应的苯胺，这是药物美沙拉秦的直接前体。当硝基化合物的起始浓度增加几个数量级并且在室温和大气压下发生时，转化也是选择性的。光催化剂可以重复使用。光催化反应也可以在曝气条件下进行，而不会损失选择性和效率。所有这些因素都表明了这一重要合成在温和条件下的可行性。