Summary On reaction with sulfur monochloride, followed by the reduction of the resulting dithiochloride with sodium sulfide, 3, kbenzpyrene gives the 5-mercaptan and 1, 2- benzanthracene is converted into its 10-mercapto derivative, as shown by the synthesis of the identical compounds from known halides by reaction with potassium hydrosulfide, and through the interaction of the magnesium derivative with sulfur, respectively. 1, 2-