Methylgranatic acid

Oxidation by Chromic Acid. Under mild conditions, e.g., in acetic acid at atmospheric temperature this converts the dihydric alcohol or keto-alcohol bases to diketo-bases, e.g., the lelobanidines, Ci3H2902N, to lelobanines, C13H25O2N. Under more vigorous action the keto-alcohol and the diketo-bases are oxidised to benzoic acid (side-chain, Ph. CO. ), acetic and i iropionic acids (side-chain, C2H5. CO. ) and either scopolinic acid l-methylpiperidine-2 6-dicarboxylic acid (IV)) or methylgranatic acid (l-methylpiperidine-2-carboxylic-6-acetic acid) or both, these being from the methylpiperidine nucleus with residues of the two side-chains. 

The degradation of the alkaloid to a methylpyridine derivative can be effected through JV-methylgranatic acid (XV) and granatic acid (XVI). The latter, when heated with mercuric acetate and acetic acid at 150° yields 2-methylpyridinecarboxylic acid, which on distillation furnishes 2-methylpyridine. 

Careful oxidation of lobinine removes two hydrogen atoms with the resulting formation of an optically active diketone, lobinanine, CisHjsOaN (designated earlier as lobinone, perchlorate, m.p. 133°, hydrochloride, m.p. 94°, [aJo — 18.6°) whereas vigorous oxidation with chromic acid produces benzoic acid and an unidentified acid which is identical neither with scopolinic acid nor with methylgranatic acid. 

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