Aromatization hydrazone residues

Scheme 16. Aromatization of hydrazone residues formation of phenylosotriazoles.285...

Scheme 45. Different types of pyrazoles formed by aromatization of hydrazone residues.

Scheme 69. Aromatization of the hydrazone residues, formation of phenylosotriazoles.

Isopropylidene and benzylidene hydrazones of the selenazoles w hich are unsubstituted in the 5-position react with p-nitrosodiethyl-and p-nitrosodimethyl-aniline in organic solvents on heating and the addition of acetic acid or pyridine. - Thus result crystalline, deeply colored, 2-hydrazono-5-(p-dialkylaminophenylimino)selenazoles (correspondingly substituted in the 4-position), details are given in Table VII. The presence of an aromatic residue in the 4-position of the selenazole ring appears to be needed to obtain crystalline compounds. 

The reaction products of the reducing sugars and aromatic hydrazines are very useful derivatives for identification purposes. One mole of hydrazine may react to give the sugar hydrazone, or two residues may be intro-... 

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