SINTESIS DAN UJI ANTIBAKTERI SENYAWA PIRAZOLINA N1-HIDROGEN DAN N1-BENZOIL DARI VANILIN DAN VERATRALDEHIDA

PUTRA JIWAMURWA PAMA TJITDA, Dra. Tutik Dwi Wahyuningsih, M.Si. Ph.D; Prof. Drs. Jumina, Ph.D

2015 | Tesis | S2 Ilmu Kimia

Telah dilakukan sintesis turunan senyawa pirazolina N1-hidrogen dan N1-benzoil serta uji antibakteri secara in-vitro. Penelitian ini bertujuan untuk mempelajari sintesis senyawa turunan pirazolina N1-hidrogen dan pirazolina N1-benzoil serta mempelajari pengaruh N1-benzoil terhadap aktivitas antibakteri. Tahapan reaksi dimulai dari sintesis senyawa prekursor yaitu kalkon. Senyawa kalkon A diperoleh dengan mereaksikan vanilin dan 2-hidroksiasetofenon dengan adanya katalis NaOH 40% selama 4 jam. Senyawa kalkon B dihasilkan dari reaksi kondensasi veratraldehida dan 2-hidroksi asetofenon dalam kondisi reaksi yang sama pada senyawa kalkon A. Tahap kedua yaitu sintesis pirazolina N1-hidrogen. Pirazolina N1-hidrogen A disintesis dari reaksi siklisasi senyawa kalkon A dan hidrazin monohidrat selama 2 jam. Pirazolina N1-hidrogen B diperoleh dari reaksi siklisasi senyawa kalkon B dan hidrazin monohidrat selama 4 jam. Tahap ketiga yaitu sintesis pirazolina N1-benzoil. Masing-masing pirazolina N1-hidrogen A dan B direaksikan dengan benzoil klorida dan asam asetat glasial sebagai katalis selama 2 jam menghasilkan pirazolina N1-benzoil A dan B. Metode reaksi yang digunakan untuk semua tahapan sintesis yakni refluks. Elusidasi struktur produk yang diperoleh menggunakan spektrometer FTIR, GCMS, 1H- dan 13C-NMR. Uji antibakteri dilakukan dengan metode difusi sumuran terhadap bakteri Gram positif (Staphylococcus aureus, Bacillus cereus, Bacillus subtilis) dan Gram negatif (Eschericia coli, Shigella flexneri). Reaksi kondensasi Claisen-Schmidt antara vanilin dan 2-hidroksi asetofenon menghasilkan senyawa kalkon A dengan rendemen sebesar 55,39%. Reaksi kondensasi veratraldehida dan 2-hidroksi asetofenon menghasilkan kalkon B dengan rendemen 77,97%. Senyawa pirazolina N1-hidrogen A dan B telah berhasil disintesis dengan rendemen 76,22 dan 84,39%. Modifikasi pirazolina N1-hidrogen menjadi pirazolina N1-benzoil A dan B juga telah berhasil disintesis dengan rendemen 50,74% dan 82,49%. Hasil uji antibakteri menunjukkan bahwa kehadiran subtituen N-benzoil menurunkan aktivitas antibakteri dan hanya aktif pada bakteri Gram positif. Senyawa pirazolina N1-hidrogen memiliki aktivitas antibakteri yang baik terhadap bakteri Gram positif dan bakteri Gram negatif.

Syntheses of N1-hydrogen and N1-benzoyl pyrazoline derivatives and antibacterial test in vitro have been carried out. The aims of this research is studying the synthesis of N1-hydrogen and N1-benzoyl pyrazoline derivatives within study the effect of N1-benzoyl against antibacterial activity. Reaction step was started from the synthesis of precursor compound which is chalcone. Chalcone A compound was obtained by reaction of vanillin and 2'-hydroxychalcone in the presence of NaOH 40% as catalyst for 4 h. While chalcone B compound was produced by condensation reaction between veratraldehyde and 2'-hydroxychalcone in similar condition to chalcone A compound. The second step is synthesis of N1-hydrogen pyrazoline. N1-hydrogen pyrazoline A was synthesized from cyclisation reaction both chalcone A compound and hydrazine monohydrate for 2 h. Whereas N1-hydrogen pyrazoline B was obtained by cyclisation reaction of chalcone B compound and hydrazine monohydrate for 4 h. The third is synthesis N1-benzoyl pyrazoline. Each N1- hydrogen A and B pyrazolines were reacted with benzoyl chloride and acetic acid glacial as catalyst for 2 h to produce N1-benzoyl A and B pyrazolines. The synthesis method for all compound is reflux. The elucidation of structure products obtained used FTIR, GC-MS, 1H- and 13C-NMR spectrometers. Antibacterial test conducted by disk diffusion method against Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, Bacillus subtilis) and Gram-negative (Escherichia coli, Shigella flexneri). Claisen-Schmidt condensation reaction between vanillin and 2- hydroxychalcone produced chalcone A in 55.39% yield. While chalcone B was synthesized from veratraldehyde and 2-hydroxychalcone to yield 77.97%. N1-hydrogen A and B pyrazoline compounds have been successfully synthesized in 76.22 and 84.39% yield, respectively. Modification of N1-hydrogen pyrazoline into N1-benzoyl A and B pyrazolines have also been successfully performed 50.74 and 82.49% yield, respectively. Antibacterial test results indicate that the presence of N-benzoyl substituent decreases antibacterial activity and is only active on Gram-positive bacteria. While the N1-hydrogen pyrazoline compounds have a good antibacterial activity against Gram positive and Gram negative bacteria.

Kata Kunci : Pirazolina N1-hidrogen, pirazolina N1-benzoil, antibakteri/N1-hydrogen pyrazoline, N1-benzoyl pyrazoline, antibacterial.