To better understand the effects of diverse substituents on reactions leading to porphyrins, pyrrole+ aldehyde condensations and related reactions of dipyrromethanes were examined. The course of pyrrole+ aldehyde condensations was investigated by monitoring the yield of porphyrin (by UV–Vis spectroscopy), reaction of aldehyde (by TLC), and changes in the composition of oligomers (by laser desorption mass spectrometry). Reaction reversibility ...