SINTESIS DAN UJI ANTIBAKTERI SENYAWA N-FENILPIRAZOLINA DARI 6-NITROVERATRALDEHIDA DAN ASETOFENON

ARTANIA A T S, Dr. Tutik Dwi Wahyuningsih, M.Si. ; Dr. Bambang Purwono, M.Sc.

2014 | Skripsi | KIMIA

Sintesis dan uji antibakteri senyawa N-fenilpirazolina dari 6-nitroveratraldehida dan asetofenon telah dilakukan. Penelitian ini dilakukan melalui empat tahapan, yaitu nitrasi veratraldehida, sintesis kalkon dari 6-nitroveratraldehida dan asetofenon, sintesis N-fenilpirazolina dari kalkon dan fenilhidrazin, dan pengujian aktivitas antibakteri terhadap senyawa N-fenilpirazolina hasil sintesis. Nitrasi veratraldehida dilakukan menggunakan reagen penitrasi campuran HNO3 dan H2SO4 pekat melalui metode pengadukan pada suhu 5 °C selama 2 jam. Sintesis kalkon dilakukan dengan mereaksikan 6-nitroveratraldehida dan asetofenon dalam etanol dengan NaOH 2 M melalui metode pengadukan selama 4 jam pada suhu kamar. Sintesis senyawa target N-fenilpirazolina dilakukan dengan mereaksikan kalkon dan fenilhidrazin dalam metanol dengan asam asetat glasial melalui metode refluks selama 6 jam. Elusidasi struktur semua produk dilakukan menggunakan spektrometer IR, GC-MS, 1H dan 13C-NMR. Senyawa N-fenilpirazolina hasil sintesis diuji aktivitas antibakterinya secara in vitro terhadap Staphylococcus aureus, Bacillus cereus, Bacillus subtillis, Escherichia coli, dan Shigella flexneri menggunakan metode difusi sumuran. Hasil penelitian menunjukkan bahwa nitrasi veratraldehida menghasilkan produk 6-nitroveratraldehida dengan rendemen 80%. Sintesis kalkon antara 6-nitroveratraldehida dan asetofenon menghasilkan senyawa 3-(4,5-dimetoksi-2-nitrofenil)-1-fenilprop-2-en-1-on dengan rendemen 18%. Sintesis N-fenilpirazolina antara kalkon dan fenilhidrazin menghasilkan senyawa 5-(6-nitroveratraldehida)-4,5-dihidro-3-fenil-N1-fenilpirazolina dengan rendemen 88%. Uji antibakteri menunjukkan bahwa senyawa pirazolina memiliki aktivitas antibakteri terhadap bakteri Gram positif dan Gram negatif dengan nilai DDH/konsentrasi pada Staphylococcus aureus (7,25/1000), Bacillus cereus (6,75/300), Bacillus subtillis (6,75/500), Escherichia coli (6,50/500), dan Shigella flexneri (5,5/1000).

Synthesis and antibacterial test of N-phenylpyrazoline compound from 6-nitroveratraldehyde and acetophenone had been carried out. The research was carried out through four steps, i.e.: nitration of veratraldehyde, synthesis of chalcone from 6-nitroveratraldehyde and acetophenone, synthesis of N-phenylpyrazoline from chalcone and phenylhidrazine, and antibacterial test of the N-phenylpyrazoline compound. Nitration of veratraldehyde was carried out using a mixture of concentrated HNO3 and H2SO4 as nitrating agent under stirring method at 5 °C for 2 hours. Synthesis of chalcone was performed by stirring 6-veratraldehyde and acetophenone in ethanol using NaOH 2 M for 4 hours at room temperature. Synthesis of N-phenylpyrazoline was conducted by refluxing the chalcone and phenylhidrazine in methanol in the presence of glacial acetic acid for 6 hours. Structure elucidation of all products was confirmed by IR, GC-MS, 1H and 13C-NMR spectrometers. The N-phenylpyrazoline compound was tested for its antibacterial activity by agar well-diffusion method against Staphylococcus aureus, Bacillus cereus, Bacillus subtillis, Escherichia coli, and Shigella flexneri. The result showed that nitration of veratraldehyde produced 6-nitroveratraldehyde in 80% yield. Synthesis of chalcone from 6-nitroveratraldehyde and acetophenone yielded 3-(4,5-dimethoxy-2-nitrophenyl)-1-phenylprop-2-en-1-one in 18%. Synthesis of N-phenylpyrazoline from chalcone and phenylhidrazine produced 5-(6-nitroveratraldehyde)-4,5-dihydro-3-phenyl-N1-phenylpyrazoline in 88% yield. Antibacterial test showed that pyrazoline was active against Gram positive and Gram negative bacteria with the value of inhibition zone/concentration against Staphylococcus aureus (7.25/100), Bacillus cereus (6.75/300), Bacillus subtillis (6.75/500), Escherichia coli (6.50/500), and Shigella flexneri (5.5/1000).

Kata Kunci : pirazolina, kalkon, veratraldehida, antibakteri