UNUSUAL SENSITIVITY TO THE CONCENTRATION OF ETHANOL IN THE BORON TRIFLUORIDE ETHANOL-CATALYZED SYNTHESIS OF 5,20-TETRAKIS(4-CYANO-2,6-DIMETHYLPHENYL)PORPHYRIN BY THE LINDSEY METHOD/

The boron trifluoride/ethanol-catalyzed condensation of 4-cyano-2,6-di methylbenzaldehyde 1b with pyrrole by the Lindsey method to give the n ew, ortho-disubstituted 5,20-tetrakis(4-cyano-2,6-dimethylphenyl)porph yrin 2 was found to be highly sensitive to the concentration of ethano l. in the absence of ethanol the yield of porphyrin is only 1%. Yields can be increased to 20-25% with ethanol concentrations of 0.05-0.1% ( v/v) but they decrease rapidly at higher concentrations of ethanol. Op timized procedures for the preparation of both 1b and 2 are described and the newly synthesized molecules are characterized by nmr (H-1 and C-13) mass spectra and elemental analysis.