To investigate the formation process of high carbon number (>C32) sedimentary porphyrins, heating experiments of several porphyrins were performed. Chromic acid oxidation of the heating products of protoporphyrin IX dimethyl ester afforded 2-methyl-3-n-propylmaleimide as the predominant product among the side-chain extension products formed. On the other hand, saturated substituents of etioporphyrin were also extended on heating to slowly form normal and branched homologs. These results may suggest that the transalkylation of porphyrin side chains proceeds mainly by a regioselective mechanism involving alkyl radical addition to a vinyl group of chlorophylls or their diagenetic products.
为了研究高碳数(>C32)沉积
卟啉的形成过程,对几种
卟啉进行了加热实验。将前
卟啉IX二
甲酸酯的加热产物进行
铬酸氧化,得到了作为主要产物的2-甲基-3-n-丙基马来
酰亚胺。此外,乙基
卟啉的饱和取代基在加热过程中也被延伸,缓慢形成正常和支链同系物。这些结果可能表明,
卟啉侧链的转烷基化主要通过一种区域选择性机制进行,该机制涉及烷基自由基与叶绿素或其成岩产物的
乙烯基团的加成反应。