pyridine; oxygen in pyridine CuBr in pyridine was saturated with O2, soln. was purged with Ar and under Ar quinone was added, mixt was left overnight; product was filtered off, washed with pyridine and ether, dried in vac., to the filtrate ether was added, crystals were filtered off, washed with ether, dried in vac.; elem. anal.;