The nitration of 3-bromopropane-1,2-diol (I) with HNO3 and H2SO4 in dichloromethane gives the dinitrate (II), which is treated with Na2S2O3 in hot methanol/water to yield the Bunte salt (III). Finally, this compound is oxidized with H2O2 catalyzed by H2SO4 in ethanol/water to afford the target disulfide. Alternatively, the Bunte salt (III) can also be obtained as follows: The nitration of 3-chloropropane-1,2-diol (IV) with HNO3 and H2SO4 in dichloromethane gives the dinitrate (V), which is then treated with Na2S2O3 as before