Kinetics of trioctylmethylammonium methyl carbonate

CHED 336

Kara Becvar, Chris Fry, Gary W. Earl, earl@wise.augie.edu, and Duane E. Weisshaar. Department of Chemistry, Augustana College, Sioux Falls, SD 57197
Quaternary ammonium compounds (quats) are widely used in fabric softeners, hair conditioners, and cleaners. These compounds are produced in industry using dimethyl sulfate or methyl chloride, which are hazardous to the environment and mutagenic. We have developed an eco-friendly route for the methylation of tertiary amines to form the quat using dimethyl carbonate (DMC). Previous work investigated the kinetics of the reactions of tributylamine, trihexylamine, and trioctylamine with DMC at three temperatures using ion exchange HPLC with an acidic eluent to analyze the reaction mixture. Poor resolution for the trioctylamine and quat led us to repeat that work. The kinetics at three additional temperatures were also determined. These results were consistent with the previous work. The Arrhenius plot yielded an Eact = 77 kJ/mole and an Sact = 2.2*102 J/(K*mol). Analysis of the data clearly indicated that more than three temperatures are needed to adequately define the Arrhenius plot.