Hydrogenolyses of Thianthrene, Phenoxathiin and Phenothiazine over Molybdenum Trisulfide Catalyst

The hydrogenolyses of thianthrene (1), phenoxathiin (2) and phenothiazine (3) over molybdenum trisulfide catalyst were carried out at 250-400°C under a pressure of 25-75 kg/cm2. These compounds contain two hetero atoms S and X (X : S, O, or N). The results of intramolecular competitive hydrogenolyses of these compounds were compared with those with phenyl sulfide (4), phenyl ether (5) and diphenylamine (6) under the same conditions, and the ease or difficulty in the cleavage of C-S-C linkage in the presence or absence of C-X-C linkage was examined. The main conclusions from these results are as follows. 1. Proportions of the hydrogenolysis of C-S-C linkage were 100% in (1), (2) and (3) and 4.2% in (4) at 250°C, 50 kg/cm2 ; these data indicate that (1), (2) and (3) are more easily cleaved than (4). 2. The C-X-C linkage produced in reaction process of (1), (2) and (3) is more easily cleaved than that in (4), (5) and (6). 3. The ease of cleavage of C-X-C linkage decreased in the order of S>>O≥N. 4. The hydrogenolysis pathways of (1), (2) and (3) were suggested by comparing the relationship between the reaction conditions reaction products.