Analysis of water content in esterification of isoamyl acetate by using gas chromatography-thermal conductivity detector with watercol 1910 column

Abstract

Excess presence of water would affect the equilibrium stability of esterification reaction and cause reduction of ester formation. Gas chromatography –thermal conductivity detector (GC-TCD) with Watercol 1910 Column was used as an analytical tool to detect water content in esterification reaction between isoamyl alcohol and acetic anhydride. The effects of split ratio and carrier gas flow rates were studied in GC setting for sample analysis. To validate the analysis method, samples from esterification reaction at 80 °C at different reaction times were directly analyzed. Slow carrier gas flow rate caused the peak of the chromatography not separated evenly and required longer time to analyze the sample. However, higher carrier gas flow rate caused shorter chromatograph peaks (reduced analysis sensitivity) and shorter analysis duration. Split ratio more than 2:1 unable to detect the presence of acetic anhydride in the sample. Carrier gas flow rate of 2.5856 mL/min and 1:1 split ratio was used to analyze the samples from the esterification reactions. All the samples from esterification reactions showed the presence of water and other compounds. The presence of water in all sample indicated that second reaction of the esterification reaction between acetic acid and isoamyl alcohol took place. The presence of water slightly affected the reaction equilibrium, promoting the hydrolysis of isoamyl acetate and reduced the formation of isoamyl acetate from 2.7 mol/L to 2.2 mol/L when esterification reaction time extended from 60 to 90 min.