Affiliation:
1. Department of Chemistry, Faculty of Mathematics and Natural Sciences, Brawijaya University, Malang, Indonesia
Abstract
The wide therapeutic effect of quinone-based drugs has received considerable interest for a long time. In this research, Friedel-Crafts performed a facile synthesis of quinone derivatives using the mixture of Brønsted acid. Reflux of 2,3-dimethylhydroquinone (1), isopropanol, glacial acetic acid, and H2SO4 for 15 minutes gave yellow oil product of 5-isopropyl-2,3-dimethylbenzene-1,4-diol (2) as a major product. Characterization using Nuclear Magnetic Resonance (NMR) revealed the methine proton splitting for isopropyl at δ 3.13 ppm, which has a cross-coupling with aromatic carbon at δ 119.6 ppm suggested the substitution of a proton on quinone ring with isopropyl group. Analysis Fourier Transform Infra-Red (FT-IR) showed the broad spectrum of –OH, the vibration of CH sp3, and isopropyl groups. The minor products identified as 5-isopropyl-2,3-dimethylcyclohexa-2,5-diene-1,4-dione (3), 5-isopropyl-2,3-dimethyl-1,4 phenylene diacetate (4), and 2,3-dimethylbenzene-5,6-isopropyl-1,4-diol (5) confirmed from 2D HETCOR and MS analysis. The partition coefficient (log P) of compound 2 showed a higher solubility by 1.9-fold compared to hydroquinone 1. It is suggested that an additional methyl group increased the partition into the organic phase.
Publisher
Institute of Research and Community Services Diponegoro University (LPPM UNDIP)