o-Nitroaniline derivatives. Part 12. The reaction of N-(2,4-dinitrophenyl)-sarcosine ethyl ester with bases: some novel redox processes revealed by X-ray crystallography

Abstract

According to the base used, the title reaction gives either 2-amino-2′-methylamino-5,5′-dinitro-ONN-azoxybenzene (9) or 2,2′-bis(methylamino)-5,5′-dinitroazoxybenzene (10), together with 1-hydroxy-4-methyl-7-nitroquinoxaline-2,3-dione (13). Reaction of compound (13) with thionyl chloride gives 5-chloro-1-methyl-6-nitroquinoxaline-2,3-dione (12). Possible mechanisms for these novel reactions are discussed.

The structures of (i) the diacetyl derivative [viz. (8)] of the azoxy compound (9), (ii) compound (12), and (iii) the monohydrate of (13), have been established by X-ray crystallography. All three compounds give monoclinic crystals. Compound (8) has space group P2₁/n, with 4 molecules in a cell of dimensions a= 19.949(4), b= 10.289(4), c= 9.101(2)Å, β= 97.98(2)°; R= 0.030 for 1 270 reflections. Compound (12) has space group P2₁/c, with 4 molecules in a cell of dimensions a= 6.922(1), b= 10.857(3), c= 13.192(2)Å, β= 100.87(1)°R= 0.055 for. 956 reflections. Compound (13)·H₂O has space group C2/c, with 8 formula units in a cell of dimensions a= 16.130(3), b= 7.173(1), c= 18.215(3)Å, β= 97.67(2)′; R= 0.037 for 1 244 reflections.