Abstract

Continuous-flow Synthesis in Milli-reactors using Microwave Heating

Lubabalo Mafu, Research Scientist, Nelson Mandela Metropolitan University (NMMU)

In this work the optimization of the solvent-free acetylation of para-menthane-3,8-diol (PMD) with acetic anhydride under microwave heating over a polymer-supported scandium triflate was performed. The central composite design (CCD) was used create a set of 13 experiments; the experimental domain (reaction time from 0.75 to 3.8 hours, reaction temperature from 60 to 80°C) was used. The catalyst loading (1.0 g) was fixed for the study. The microwave-assisted continuous-flow reactor with irradiation power from 500 to 700 watts at a frequency of 2.45 GHz was used for the study. The catalyst was packed in the glass reactor column (I.D. = 6 mm and length = 120 mm). The PMD conversion, mono-ester and di-ester selectivity were studied. The progress of the reaction was followed by the gas chromatogram (GC) and the compounds were separated by column chromatography. The pure samples were analyzed by the FT-IR, 1H-NMR, 13C-NMR and GC-MS.