Study of deuterium transfer,isotope effects and structural distributions of products of reactions of coals in deuterated tetralin using 2H and 13C FT-n.m.r. and solid-state 13C FT-n.m.r.

Four coals (bituminous, subbituminous, lignite and canneloid) are treated with tetralin-1,1,4,4,-d₄ or — 1,1 -d₂ or mixtures of tetralin-d₄ and tetralin-d₀ at 427 °C in degassed Pyrex vessels for times between 5 and 60 min. Deuterium depletion and scrambling in solvent-derived products are determined for degassed and air-saturated experiments. Deuterium distributions are determined for preasphaltene and asphaltene fraction (A + P) and light oils (LTO) by ²H FT-n.m.r., and solid coals and products are characterized by ¹³C CP/MAS and ¹³C FT-n.m.r. Illinois No. 6, PSOC 837 and PSOC 531 coals selectively consume tetralin-d₀ over tetralin-d₄ and exhibit isotope effects in the scrambling of deuterium from 1 — to 2-positions. Intersite deuterium scrambling in recovered tetralin is negligible at 10 min or shorter reaction times, but deuterium depletion from tetralin is significant at all reaction times. Deuterium is detected predominantly at benzylic-type and secondary aliphatic positions and to a lesser extent at aromatic positions of A + P and LTO fractions at reaction times of 5 min. The presence of air significantly enhances both the extent of deuterium scrambling and the rearrangement of tetralin to 1-methylindan at reaction times of 30–60 min.