SINTESIS SENYAWA KHALKON DAN FLAVON DARI VANILIN SEBAGAI ANTIOKSIDAN DAN ANTIBAKTERI; SYNTHESES OF CHALCONES AND FLAVONES FROM VANILLIN AS ANTIOXIDANT AND ANTIBACTERIAL

Susanti VH, Elfi, Sabirin Matsjeh

2016 | Tesis | FMIPA

Syntheses of flavones derivatives from raw materials vanillin had been conducted via several steps of reaction, i.e : methylation, Claisen-Schmidt condensation, cyclization and demethylation. The synthesized chalcones and flavones have been tested as antioxidant and antibacterial agent. Methylation of vanillin was carried out by the use of dimethylsulphate to give veratraldehyde. Then, it was reacted with hydroxy acetophenone derivatives by Claisen-Schmidt condensation to produce four chalcones (chalcone 1, chalcone 2, chalcone 3 and chalcone 4). The chalcones derivative were synthesized by conventional method (using solvent) and grinding technique (free solvent). The chalcones undergo cyclization reactions using iodine in DMSO to yield flavones (flavone 1, flavone 2, flavone 3 and flavone 4). The flavones were demethylated by using HBr and glacial acetic acid. Characterization of the compounds were conducted using FT-IR, GC-MS, 1H- and 13C-NMR. All the product, chalcones and flavones were tested for their antioxidant activity in vitro by DPPH method, and tested as antibacterial agent against Gram-negative and Gram-positive using filter paper disc dillution method. The result showed that veratraldehyde has been succesfully methylated from vanillin in 73% yield with m.p 42-43 °C. Synthesis of chalcone by conventional condenzation yielded chalcone 1 (75%), chalcone 2 (70%), chalcone 3 (45%), and chalcone 4 (65%). While the grinding techniques gave chalcone 2 (84%), chalcone 3 (73%), and chalcone 4 (70%). Syntheses of chalcone by grinding technique have been required a shorter reaction time (15 minutes) and a greater yield (70-84%) compared with conventional method (45-75%). The cyclization of chalcone derivatives have produced flavone 1 (39%), flavone 2 (30%), flavone 3 (22%) and flavone 4 (27%). In an attempt to demethylate all flavones, only flavone 4 could be demetilated into 5,4'-dihidroksi-3'-metoksi flavon. Antioxidant activity test of chalcones and flavones gave IC50 above 100 ?g/mL showing that the antioxidant activity are low. The antibacterial activity of synthesized flavones have indicated that the flavones are active as antibacterial against E. coli, S. aureus and P. aeruginosa

Kata Kunci : vanillin, veratraldehyde, Claisen-Schmidt condensation, chalcone, flavone