A New Quantitative Determination of Olefins by Hydroboration-Methanolysis Method

Abstract

A new quantitative analytical procedure of olefins in a mixture of hydrocarbons using hydroboration-methanolysis method is described.After hydroboration of olefins in a mixture of hydrocarbons with diborane, methanol was added to decompose the excess hydrides. From the volume of hydrogen gas thus generated, the amount of olefins in the sample was calculated.Although bromine, iodine and fluorescent indicator adsorption procedures are well known as analytical procedures of olefins, these are not applicable for colored samples. In addition, bromine and iodine methods usually give larger values than the theoretical values when aromatics and isoolefins are contained in samples tested. In contrast, it was found that the present method does not have such defects and gives moreaccurate data. The olefins in a thermal cracked oil of an atmospheric residual oil were analyzed by the method.Finally, the determination of diolefin contents in a mixture containing monoolefins was proposed, based on the facts that fluorescent indicator adsorption technique analyzes diolefins, not as olefins but as aromatics, and that the present method gives all olefins as olefin contents.