Porphyrins. Part 38. Reaction of Porphyrins Containing Hydroxy(alkoxy)ethyl or Alkoxymethyl Substituents with Nucleophiles in the Presence of Zinc Acetate. A Novel, Promising Method for the Modification of Porphyrins on the Periphery of the Macrocycle. --(PONOMAREV, G. V.; KIRILLOVA, G. V.; YASHUNSKY, D. V.; Chem.