350 



R. Lemberg, p. Clezy and J. Barrett 



accompanying dehydration to vinyl or substituted vinyl, which was achieved 

 by heating in acetic acid or in pyridine plus toluene-sulphonylchloride. The 

 introduction of the vinyl at position 2 lowered, as expected, R III/IV of 

 porphyrin a acid from 1-75 to 1-50. The a-hydroxyalkyl group is therefore 

 present on ring I (in position 2) between the two rhodofying groups at rings 

 II and IV. 



Possible Formulae of Porphyrin a 



These findings can be summarized as establishing one of the two formulae 

 of Fig. 3 for porphyrin a. 



CHOH 



CHO 



H,C 



OHC 



CO2H COgH 



I n 



Fig. 3. Alternative formulae for porphyrin a 



Nicolaus (private information) has been unable to obtain the pyrrole 

 carboxylic acids 



CH 

 HO,C 



XN 



c^^3 



CO2H HOpC 



C02H 



OgH 



from the nitrile of porphyrin a oxidized by his alkahne permanganate method. 

 This would seem to exclude formula I and support formula II of Fig. 3. 

 However, the value of such negative evidence is uncertain. Dr. Clezy is 

 attempting to solve this problem by Wolflf-Kishner reduction of the formyl to 

 methyl. A resorcinol melt of the product should then give deuteroporphyrin 



