Method for determining the olefinic content of the saturated and aromatic fraction of petroleum distillates by hydroboration

This study was prompted by a perceived need for a reliable method for determining olefin content in petroleum distillate fractions. An improved analytical method for the determination of olefin content in naphtha and higher boiling distillate fractions is described. The procedure comprises quantitative addition of diborane that specifically converts the olefins in the saturated and aromatic portion of the petroleum to alcohols. The reaction mixture is chromatographed on alumina, and alcohols are eluted with dichloromethane. The procedure was applied to two hydrocarbon mixtures of 20 saturated, olefinic and aromatic hydrocarbons in the investigated boiling range. Naphtha (ibp–200 °C) and light gas oil (200–350 °C) fractions from the Lloydminster oil were also analysed. Results are compared with the standard FIA method, and a method utilizing both the FIA and proton magnetic resonance spectrometry.