Rothemund reaction

[3][4] This has inspired the work of his student Paul Rothemund to develop a simple one pot synthesis of porphyrins.

In 1935, Paul Rothemund reported the formation of porphyrin, from a simple reaction of pyrrole with gaseous acetaldehyde or formaldehyde in methanol followed by treatment with various concentrations of hydrochloric acid.

[5] One year later Paul Rothemund announced the applicability of his reaction to other aldehydes, by which he was able to explore large number of porphyrins.

He performed the porphin synthesis at a temperature of 90-95 °C and high pressure in sealed pyrex glass tubes, by reacting pyrrole, 2 % formaldehyde and pyridine in methanol for 30 hours.

[9] Green chemistry variants have been developed in which the reaction is performed with microwave irradiation using reactants adsorbed on acidic silica gel[10] or at high temperature in the gas phase.