Direct photolyses at> 200 nm of l-bromc-and l-iodo-l-hexynes were performed in polar and nonpolar solvents. Only radical-derived products were obtained even in polar solvents, contrary to the previously reported ionic photochemical behavior of alkyl and vinyl halides. The results are discussed from an energy point of view; the ionization potential of the initially formed organic radical well accounts for the obvious difference in photobehavior between ...
