Dibenzoyl disulfide

The method described is adapted from the procedures of Kym 3 and Engelhardt, Latschinoff, and Malyscheff.4 Thio-benzoic acid has been prepared by the reaction of benzoyl chloride with potassium sulfide,4 hydrogen sulfide in pyridine,6 6 and magnesium bromide hydrosulfide.7 It is formed from dibenzoyl disulfide with potassium hydrosulfide,4 potassium hydroxide,4 8 and ammonia.9 It is also formed from dibenzoyl sulfide, from phenyl benzoate, and from benzoic anhydride with alcoholic potassium hydrosulfide.4 It has been obtained from dibenzoyl sulfide and hydrogen sulfide,10 carbon oxysulfide and phenyl-magnesium bromide,11 12 dibenzyl disulfide and sodium ethoxide,13 benzyl chloride and sulfur in the presence of potassium hydroxide,14 and benzylthiosulfuric acid and alkali.18 16... 

Photolysis of aryl-desyl sulfides (LV, It = C H6) yielded didesyl (LVII).240 Desylthiobe n zoate (LV, R = SCOC6H6) gave didesyl and dibenzoyl disulfide. It is probable that in the former case the phenylthiyl radical (C0H6S ) abstracts hydrogen from the solvent to give thio-phenol and that in the latter reaction dibenzoyl disulfide is formed from the dimerization of benzoylthiyl radical (C H6COS-). The formation of LVII may be attributed to the dimerization of the desyl radical (LVI). O OH... 

However, irradiation with a tungsten-halogen lamp of the 2,5-diphenyl-l,3-dithiolylium-4-olate in the presence of oxygen in dichloromethane solution allowed isolation of dibenzoyl disulfide (139 R = Ph) together with the dimer (12 10%) (80CL717). 

Oxidation. The use of iodine as an oxidant is exemplified by a procedure for the preparation of dibenzoyl disulfide. A solution of potassium hydroxide in absolute ethanol is saturated with hydrogen sulfide and treated with benzoyl chloride at 15°. The potassium chloride formed is removed by filtration, and iodine is added to the filtrate in the amount required to complete the oxidation. 

Benzoyl disulfide (dibenzoyl disulHde) [644-32-6] M 174.4, m 131.2-132.3. About 300mL of solvent is blown off from a filtered solution of dibenzoyl disulfide (25g) in acetone (350mL). The remaining acetone is decanted from the solid which is recrystallised first from 300mL of 1 1 (v/v) EtOH/ethyl acetate, then from 300mL of EtOH, and finally from 240mL of 1 1 (v/v) EtOH/ethyl acetate. The yield is about 40% [Pryor Pickering J Am Chem Soc 84 2705 1962]. [Beilstein 9 H 424, 9 II 289, 9 III 1977.] Handle in a fume cupboard because o/TOXICITY and obnoxious odour. 

Copper(I) salt promoted reaction of styryl bromides with dibenzoyl disulfide in a hot aprotic polar solvent produces 2,4-diarylthiophenes (421) in moderate yields (Scheme 84) <92CL1947>. The reaction may involve addition of PhCOS radical to the double bond of the substrate (activated by copper(I) salt), further addition of the resulting radical (420) to the substrate, and intramolecular radical substitution with extrusion of benzoyl radical followed by elimination of hydrogen bromide. 

Benzoyl disulfide (dibenzoyl disulfide) [644-32-6] M 174.4, m 131.2-132.3". About 300ml of solvent is... 

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