Metahemipinic acid

Calculating from the yield of metahemipinic acid (38) on degradation of lignins by permanganate oxidation, Miksche and coworkers estimated that there are abont 3% nnits of types 36 or 37 in softwood lignin [17] and abont 2% snch units in hardwood lignins [18] [Note the 2- and 6-positions are equivalent in syringylpropane nnits (2)]. 

In addition to the completely symmetrical pavine alkaloids, Stermitz et al. (518) found other pavine alkaloids of mrmitagine type (Tables X and XI) in Argemone munita, spp. rotundata. The location of the substituents of the two aromatic rings was determined on the one hand by the classic chemical method, i.e., isolation of hemipinic (Ilb) and meta-hemipinic (lla) acids after alkaline oxidation of 0,0-dimethylmunitagine and, on the other, by NMR analysis oxidative degradation of argemonine resulted only in metahemipinic acid (Ha) and its methylimide (III), respectively. 

Metahemipinic Acid (4 5-DvmefhoayphiJuilic arAd, veratrol-4t 5-dicarboxylic acid)... 

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