Sintesis Metil Oleat dari Asam Oleat dengan Metanol pada Perbandingan Rasio Molar dan Daya Microwave menggunakan Katalis Abu Kulit Durian

Abstract

The synthesis of methyl oleate from esterification reaction between oleic acid with methanol was performed using calcined durian peel ash as catalyst and microwave irradiation has been carried out. Durian powder was heated at 600°C for 4 hours. The main component of calcined durian peel ash is K2O of 85,15%. The reaction conditions carried out in this study were the molar ratio oleic acid to methanol of (1:1, 1:3, 1:6, 1:9, 1:12, 1:15, 1:18) and microwave power (20P, 40P, 60P, 80P, 100P) with catalyst weight 18% and 20 minutes reaction time in each variation. The methyl oleate conversion was determined using alcalimetric titration method and the maximum conversion was confirmed using gas chromatography and FT-IR spectrophotometer. The conversion and yield of methyl oleate of 92,25% ±1,88% and 86,42% ±0,79% was obtained at ratio 1:9, a catalyst weight 6% (w/w), 20 minutes reaction time, and microwave power 60P. The gas chromatography showed that the conversion of methyl ester reached 93,39% and analysis FT-IR spectrophotometer shows that there is an absorption of -C=O stretching ester at wave number 1743.65cm-1 and there is no stretching vibration of carboxylic acid -OH groups in the wave number area 3400-2400 cm-1 and supported by the characteristic stretching absorption band of the -C-O-C- group in the 1300-1000 cm-1 area where the absorption band with the smallest wave number on the right experiences increase in absorption intensity. Therefore, it can be concluded that there has been a process of substitution of the -OH group of carboxylic acid with the -OCH3 group of methanol.