A variety of alcohols can be dehydrodimerized to give 1, Zdiols on a multigram scale at 1 atm pressure and reflux temperature on photolysis (254 nm) in the presence of a trace of Hg vapor. Initial CH bond breaking is followed by recombination of the resulting aC-centered radicals, which normally leads to CC bond formation a to oxygen. The reaction rate and selectivity can be increased by operating at lower temperatures under Hz, in which case H ...