The influence of catalyst (p-TSA) weight percentage on reaction rate during the oleic acid esterification process with trimethylolpropane

In the present work the kinetics of the acid-catalyzed esterification reaction of oleic acid with trimethylolpropane was described, by carrying out of the process under vacuo at 120°C and applying different weight percentage (w%) of p-TSA as a catalyst. The reaction was studied at following percents of p-TSA: 0 w%, 0.5 w%, 1 w% and 5 w% and the duration time of 1200 min. The reaction kinetics was monitored by analyzing the acid value of the aliquots taken from the mixture. Authors noticed that the highest reaction rate of the process as well as the best results in regard to the yield of the obtained product were achieved using 5 w% of p-TSA. However, darkening of the mixture was observed, probably due to the oxidation process, which reduces the purity and quality of the resulting product. Moreover, some problems with product purification during washing of the reaction mixture were observed, probably due to increasing of emulsification properties of reaction mixture at higher weight percents of catalyst. Therefore, in order to select the optimal reaction conditions, the percent of catalyst must be precisely selected by variations in the range between 2 w% and 5 w% p-TSA relative to oleic acid.