THE PHOTOADDITION OF PYRROLES TO ARYLETHENES AND ARYLETHYNES

The photochemical reactions of styrene, (E)-stilbene, phenylethyne, an d diphenylethyne with pyrrole and N-methylpyrrole have been investigat ed. The pyrroles quench the fluorescence of the phenylethenes and phen ylethynes efficiently and broad structureless emissions attributed to exciplexes are observed from the N-methylpyrrole systems. Substituted pyrroles (1:1 and 2:1 adducts) are formed from irradiation of the phen ylethenes with pyrrole, and 2-styrylpyrroles result from the phenyleth ynes. Styrene, but none of the other arenes, undergoes photoaddition t o N-methylpyrrole in the presence of 10% acetic acid.