Preliminary study on online monitoring with spectrometry for esterification of isoamyl acetate.

Ultraviolet-visible (UV-Vis) spectrometry with the application of ultraviolet and visible ranges of the electromagnetic spectrum able to measure the coloured solution sample. Spectrometry was successfully used in online monitoring of miniaturized processes. However, until now there is no literature reporting on the application of online UV-Vis spectrometer usage for esterification. In this work, an online UV-Vis spectrometer with the light wavelength range of 340-1050 nm was used to determine the concentration in the esterification reaction of acetic anhydride. Methyl yellow was used as an indicator for acetic anhydride. Different volume ratios of acetic anhydride (AcAn) in acetic acid (AAc) were prepared. Effect of absorbance on different flow rates was conducted by varying the flow rates. Esterification of isoamyl alcohol with acetic anhydride was conducted in a miniaturized intensified reactor at 80 oC. Sample with 100 vol% AcAn showed a single absorbance peak at 410 nm. Meanwhile, AcAn at 0 to 90 vol% showed two absorbance peaks at the wavelength of 410 nm and 530 nm. The absorbance of 100 vol% AcAn was around 0.55. Meanwhile, absorbance for 0 vol% of AcAn at the wavelength of 410 nm and 530 nm were around 0.4. Insignificant absorbance changes when the flow rate varied from 0 to 100 µL/min. Absorbance of AcAn dropped from 0.51 to 0.13 at the end of esterification reaction where up 95% of AcAn used in the esterification. [ABSTRACT FROM AUTHOR]