Photolysis of Some Cyclic Disulfides*

Photolysis of liquid pentarnethylene disuliide, liquid tetramethylene disulfide and liquid l, 4‐butanedithiol has been studied. Photolysis of the cyclic disulfides by irradiation in their lowest energy absorption band produces the corresponding dithiol; photolysis of alkali‐doped cyclic disulfide at the same irradiation wavelength as above produces the corresponding cyclic monosulfide. It is suggested that photolysis of undoped liquids proceeds via ‐S‐S‐ scission, whereas that of the doped liquids is supposed to involve initial ‐CS‐ scission. Photolysis of the dithiol produces the corresponding cyclic monosulfide, the rate of such production being considerably enhanced in the presence of alkali. Much of the above data and suggestions are rationalized using a simple MO formalism, which also involves an attempted interpretation of much of the electronic spectra of the various compounds. Product identification was made by study of the short wavelength absorption spectrum of the vapor in equilibrium with the photolysed material.