Reactions of mercury(II) acetate with nitrogen compounds. Part 3. Contrasting reactions of mercury(II) and lead(IV) acetates with some semicarbazones: bis(5,6-diphenyl-1,2,4-triazin-3-onato)mercury

Abstract

Treatment of benzil monosemicarbazone with lead tetra-acetate in acetic acid gave O-acetylbenzoin in a fragmentation involving phenylbenzoyldiazomethane as an intermediate. Treatment of benzil monosemicarbazone with mercury(II) acetate gave bis(5,6-diphenyl-1,2,4-triazin-3-onato)mercury. Benzil bis-semicarbazone and some benzaldehyde semicarbazones gave stable aminomercury compounds when treated with mercury(II) acetate and, in contrast with lead tetra-acetate, dehydrogenations or fragmentations did not occur. Lead tetra-acetate fragmentation of the hydrazone system ArC(ArCY)NNHX (Y = O or NR) to a diazo species, which may cyclise or react further, appears to be a useful general reaction when X is a good leaving group, e.g. CONH₂ or SO₂Ar.