Decomposition of Organic Sulfur Compounds by Metallic Sodium --Acceleration Effect of Tetralin and Inhibition Effect of Aromatic Hydrocarbons on the Decomposition of Thiophene

As a part of research on the removal of sulfur from petroleum and coal products with metallic sodium, the susceptibility to the decomposition of organic sulfur compounds having different structural features by metallic sodium and factors affecting the decomposition of thiophene have been investigated. Reactions were carried out in a glass ample containing the stoichiometric amount of sodium (assuming conversion of S to Na2S) at 200°. In hexane or xylene, diphenyl sulfide and benzo[ b ]thiophene were readily decomposed, while the decomposition rates of thiophene, dibenzothiophene and dibutyl sulfide were comparatively slow (Fig.1 and 2).2-Butanethiol was resistant to the decomposition. The decomposition of thiophene was markedly affected by solvents used, and was found to be very rapid in tetralin and very slow in benzene (Fig.3). The great acceleration effect of tetralin has been suggested to be attributed to the great hydrogen-donating capability, because the addition of tetralin and other aromatic hydrogen donors to a benzene solution accelerated the decomposition in accordance with relative hydrogen-donating capabilities of the additives (Table 1). On the other hand, naphthalene and phenanthrene, the reduction poduction potentials of which are lower than that of benzene, caused greater decrease in the thiophene decomposition efficiency than benzene (Table 2). This inhibitory action of aromatic hydrocarbons is probably due to the electron transfer process from sodium to the hydrocarbons which is competitive with the electron transfer to thiophene. The fact that thiophene was hardly decomposed in benzene may be interpreted in the same way. Hydrogen gas also retarded the thiophene decomposition (Table 4).