Hydrogen transfers in tetralin

Abstract H-transfers for upgrading of bridge polyaromatic structures in coal liquids and heavy oil fractions were studied in tetralin (THN) as H-donor model system. Symmetrical hydrogenation of t -stilbene (ΦCHCHΦ), in the presence of diphenyldisulfide (ΦSSΦ), and scission of bibenzyl (BB), as representative of consecutive stages of a same process, were investigated. The results have shown that (1) reduction of t -stilbene to BB, at 350 °C, occurs with stoichiometric yield (100%) when accelerated by addition of diphenyldisulfide as radical generator; (2) scission of BB, at 360–422 °C, takes place for 99.7 to 95.4% according to an unsymmetrical mechanism (formation of benzene) due to H-ipso attack from THN to stronger C ar C al bonds and for the remaining 0.3 to 4.6% with a symmetrical mechanism (formation of toluene) due to weaker C al C al bond homolysis.