Mohammad Farid Rahman
Department of Chemistry, Faculty of Mathematics and Natural Sciences, Brawijaya University, Malang|Brawijaya University|Indonesia

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Effect of methyl substituent on the solubility of 1,4-benzoquinone derivatives in n-octanol/water system Siti Mariyah Ulfa; Fath Dwisari; Ade Cintyia Sally; Mohammad Farid Rahman
Jurnal Kimia Sains dan Aplikasi Vol 23, No 5 (2020): Volume 23 Issue 5 Year 2020
Publisher : Chemistry Department, Faculty of Sciences and Mathematics, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2428.245 KB) | DOI: 10.14710/jksa.23.5.142-146

Abstract

The solubility of the compound is a crucial task for new drug design. Quinone is a promising candidate to develop as a new drug. In this research, the synthesis of 1,4-benzoquinone derivatives, that is, 2-(5-bromoamyl)-3,5-dimethyl-1,4-benzoquinone (2a) and 2-(5-bromoamyl)-5-methyl-1,4-benzoquinone (2b) were carried out by decarboxylation and insertion reaction of alkyl bromides. The product 2a and 2b are purified using SiO2 gel column chromatography and analyzed by UV-Visible, FT-IR, and NMR. The yield of 2a is 13.75%, and 2b is 4.04%. The solubility of 2a and 2b, expressed by log P, is measured in the n-octanol/water (3:7 (v/v)) system by the shake flask method. The log P of 2a and 2b are 2.99 and 1.36, respectively. It is showed that the log P of 2a is higher compared to 2b. The presence of two methyl substituents on the quinone ring of 2a supports the increase of hydrophobicity of the compound in the n-octanol/water system.
Facile synthesis of 5-Isopropyl-2,3-dimethylbenzene-1,4-diol by Friedel-Crafts and Determination of Partition Coefficient in n- Octanol/Water Siti Mariyah Ulfa; Alma Miranda; Fath Dwisari; Mohammad Farid Rahman
Jurnal Kimia Sains dan Aplikasi Vol 25, No 1 (2022): Volume 25 Issue 1 Year 2022
Publisher : Chemistry Department, Faculty of Sciences and Mathematics, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jksa.25.1.7-12

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.