KINETICS AND MECHANISM OF SPIRO ADDUCT FORMATION FROM AND SMILES REARRANGEMENT OF N-METHYL-N-(2,4,6-TRINITROPHENYL)AMINOACETANILIDE. BASE-CATALYZED TRANSFORMATION OF N-(2,4,6-TRINITROPHENYLAMINO)ACETANILIDE INTO 2-NITROSO-4,6-DINITROANILINE