Imidazolium and Ammonium Based Ionic Liquid as Mediator for Flavone Synthesis Using Microwave Assisted Organic Synthesis (MAOS)

• Main Author: Yuliana Dwi Cahya, Angelina
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/38016
• Institution: Institut Teknologi Bandung

Flavones are phenolic compounds which are found in terrestrial plants in our nature. Flavones and their derivatives have been known to posses many biological activities such as antioxidant, antiinflamation, antibacterial, anticancer and antimicrobial. In this research, ionic liquids from imidazolium and ammonium halides have been successfully synthesized and used to mediate the oxidative cyclization reaction of 1-(2-hydroxyphenyl)-3-phenyl-1,3- propandione into 2-phenyl-4H-1-benzopyran-4-one. Ionic liquids that acts as a mediator were prepared by reacting 1-methylimidazole with haloalkanes (n-chlorobutane; n- bromodecane; n-bromododecane) or N,N,N-triethylamine with n-bromodecane by Microwave Assisted Organic Synthesis (MAOS) method. Synthesis of ionic liquids took place at varying temperatures from50oC to 80oC for 21 to 80 minutes. The results are [BMIM]Cl, [DMIM]Br, [DDMIM]Br and [DTEAM]Br with chemical yields obtained 24%, 87%, 48%, and 5%respectively. TLC test for imidazolium based ionic liquids carried in chloroform:methanol (9:1, v/v) eluen systems which gave different Rf values as comparedto precursors. The 2-phenyl-4H-1-benzopyran-4-one compound was successfully synthesized in ionic liquids mediator by MAOS method which gave high chemical yields from 89% to 99%. The transformations was done in short time from 3 to 6 minutes powered by 200 Watt and at 150 oC using microwave system. TLC analysis was carried out usingn-hexane:ethyl acetate (7:3, v/v) eluen system which provide the value of retention factor (Rf) of 0,4. Flavones and ionic liquid compounds have been characterized with IR and NMR spectroscopy. Based on the FT-IR spectrum measurement of imidazolium based ionic liquids revealed typical peak from C-N group vibration wavenumber at 1164 cm-1 to 1184 cm-1 and the C=N group vibration wavenumber at 1570 cm-1. 1H NMR spectrum (500 MHz, CDCl3) measurement from ionic liquids of imidazolium derivativesshows typical proton signal of singlet aromatic group (? = 7,5 – 10,5 ppm) and a proton signal from aliphatic group (? = 1,3 – 4,2 ppm). Meanwhile, 1H NMR (500 MHz, CDCl3) spectrum of ionic liquids from ammonium derivatives shows that there are aliphatic proton signals (? = 0,7 to 3,4 ppm). Infrared spectroscopy measurement from flavones revealed typical peak vibration from C-O group wave number at 1376 cm-1 and C=O vibration wave number at 1647 cm-1. 1H NMR spectrum (500 MHz, CDCl3) of flavones showed aromatic proton signal (? = 7,4 to 8,2 ppm) and there is a singlet proton signal (? = 6,8 ppm) shows that proton have been attached to the C-ring of ethylene group. The synthesis results of 2-phenyl-4H-1-benzopyran-4- onecompound that is mediated by recycling ionic liquid have been successfully performed with high chemical yields of 94% to 99%. The synthesis products using recycled ionic liquids were compared to previous flavones and showed the same Rf value on TLC plate.