CHARACTERIZATION OF PETROLEUM RESIDUA THROUGH REDUCTIVE CHEMISTRY

ABSTRACT

Distillation residua from petroleum, containing 26 — 32% aromatic carbon (f_a), are reduced by K⁰ in tetrahydrofuran to form anions which are then alkylated by alkyl iodides. Consumption of potassium in 24 hours at room temperature is in the range 4 to 5 mmol K per gram resid, of which 19—23% goes to the formation of “K₂S” from the removal of sulfur from the resid. The anions of the resid are characterized by alkylation of the resid with ¹³C enriched methyl iodide followed by examination by heteronuclear correlated two—dimensional nuclear magnetic resonance of ¹H and ¹³C spins. Analysis of proton and carbon shifts of individual methyls demonstrates that attachment of methyls to carbon atoms of the resid is the principal chemistry of the reductive methylation.