Azoxypyridines 1-oxides

The reduction of azo- to hydrazo-pyridines has been carried out with zinc and alkali4546 sodium sulphide442e-3 and stannous chloride i, 443 Azoxy compounds have been reduced to azo compounds by zinc and alkali454, 46ia and by arsenite o and to hydrazo compounds by stannous chloride d, 457 With azoxypyridine 1-oxides the possibilities are more complicated, as illustrated36 ... 

The catalytic effect of tetra-n-butylammonium fluoride in the homogeneous reduction of heterocyclic A-oxides and nitroarenes by hexamethyldisilane in tetra-hydrofuran can occur with EXPLOSIVE violence, but can be controlled by the slow addition of the disilane to the A-oxide (or nitroarene) and tetra-n-butylammonium fluoride to yield the parent heterocycle (>70%) (or azobenzene 84%). In a similar manner, azoxybenzene is converted into azobenzene (95%), and 4-nitropyridine-l-oxide, is reduced to azoxypyridine-l,l -dioxide (78%), with minor amounts of azopyridine-1, l -dioxide and azopyridine-1-oxide [5,6]. 

Oxidation of aminopyridines with Caro s acid gives nitropyridines the use of peroxy-trifluoroacetic acid leads to nitropyridine JV-oxides (60JOC1716). Oxidation with alkaline hypochlorite converts aminopyridines into symmetrical azopyridines, and azoxypyridines are formed by oxidation with persulfate (59YZ549). 

Zinc and acetic acid convert 4,4 -azoxypyridine l,l -dioxide into 4,4 -azopyridine Ijl -dioxide , and hydrazine in presence of copper reduces it to 4-aminopyridine 1-oxide . ... 

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