The chemistry of pyrrolic compounds. XLIV. The preparation and comparative spectroscopic study of some isomeric diformyldeuteroporphyrins

Abstract

A comparative study of the electronic and ¹H n.m.r. spectra of five isomeric diformyldeuteroporphyrins has been carried out. Clear distinctions can be recognized in the electronic spectra of the diformyldeuteroporphyrins, depending on the relative positions of the two formyl groups. Since many different substituents can be converted into the formyl group, it is suggested that this correlation between substituent distribution and spectroscopic pattern may be employed as an aid in problems of structure determination. As an illustration, the method has been used to elucidate the structure of an acrylate by- product formed during the synthesis of intermediates leading to the protoporphyrins having vinyl groups in opposite pyrrolic ring systems.