Nitro quinaldine

Titanium dioxide is a convenient photocatalyst for nitro group reduction, as in many other redox processes, provided that a convenient hole trap is present. As it has been known since more than a century, irradiation of nitrobenzene in ethanol causes a redox reaction to give aniline and acetaldehyde and subsequent condensation gives easily isolated and characterized quinaldine, through what can be considered a photochemical... 

The solvent system was generally composed of nitro-methane, formic acid, and benzene, 50 1 5, and the indicator was a mixture of quinaldine red and methylene blue in anhydrous methanol. The end point was signified by a green color. 

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