Isolation of Alkylnaphthalenes from the Middle Distillate of Petroleum by Liquid-Solid and Liquid-Liquid Chromatography

For the purpose of analysing individual alkylnaphthalenes in petroleum middle distillates, an isolating method using liquid chromatography was investigated for simplicity and quantitative reliability. The alkylnaphthalenes could be isolated rapidly and quantitatively from saturates, mono-aromatics and sulfides by liquid solid chromatography using alumina of properly adjusted activity. In this chromatography, alkylbiphenyls and alkylbenzothiophenes showed the same behavior to alkylnaphthalenes.In order to separate alkylnaphthalenes from alkylbenzothiophenes a new liquid-liquid chromatographic technique was developed. Alumina or silica gel impregnated with a polar solvent had the ability to separate these compounds. Using basic alumina as the solid support and dimethylsulfoxide as the stationary liquid phase, naphthalene and benzothiophene were completely separated in preparative scale. Further, using a mixture of dimethylsulfoxide and dimethylformamide as the liquid phase, dimethylnaphthalenes in petroleum middle distillates were also successfully separated from analytically interfering C10 alkylbenzothiophenes.