SINTESIS TURUNAN SENYAWA AZO-HIDRAZON DARI VANILIN DAN UJI POTENSI SEBAGAI SENSOR ANION SECARA KOLORIMETRI

BETA ACHROMI N, Dr. Bambang Purwono, M.Sc.; Dr. Tutik Dwi Wahyuningsih, M.Si

2015 | Tesis | S2 Ilmu Kimia

Telah disintesis turunan senyawa azo-hidrazon, (2-metoksi-4-fenilhidrazon-6-(p-nitrofenilazo)fenol (3) berbahan dasar vanilin dan uji pemanfaatannya sebagai sensor anion secara kolorimetri. Senyawa 3 diperoleh melalui reaksi senyawa azo-vanilin, (4-hidroksi-3-metoksi-5-(p-nitrofenildiazenil) benzaldehida (2) dengan fenilhidrazin. Senyawa 2 dihasilkan melalui reaksi kopling diazo vanilin dengan p-nitroanilin pada suhu 0-5 derajat Celsius. Sebagai senyawa pembanding, disintesis pula senyawa vanilin-hidrazon, (3-metoksi-4-hidroksi)-1-fenil-fenilhidrazon (1) melalui reaksi antara vanilin dengan fenilhidrazin. Elusidasi struktur senyawa hasil sintesis dilakukan dengan menggunakan FTIR, GC-MS, 1H- dan 13C-NMR. Hasil sintesis senyawa 1, 2, dan 3 masing-masing memberikan rendemen sebesar 70,25; 68,22; dan 38,46%. Hasil uji efek pelarut (solvatochromic) menunjukkan senyawa 1, 2, dan 3 memberikan pergeseran bathochromic terhadap kenaikan polaritas pelarut tunggal aprotik (aseton, asetonitril, dan DMSO). Senyawa 1 menunjukkan selektifitas yang tinggi namun dengan sensitifitas yang rendah terhadap anion sianida. Senyawa 2 dalam aseton selektif terhadap anion fluorida, sianida, dan asetat dengan batas deteksi asetat hingga 0,1 mM. Senyawa 3 dalam DMSO selektif terhadap fluorida, sianida, dan asetat dengan kemampuan deteksi sianida hingga 0,2 mM. Penambahan H2O sebagai pelarut senyawa 3 dalam DMSO menurunkan kemampuan sensor dalam deteksi anion secara kolorimetri.

Colorimetric anion sensor based on azo-hydrazone derivatives, 2-methoxy-4-phenylhydrazone-6-(p-nitrophenylazo)phenol (3) from vanillin was synthesized. Compound 3 was obtained by reaction of azo-vanillin, 4-hydroxy-3-methoxy-5-(phenyldiazenyl)benzaldehyde (2) with phenylhydrazine. Compound 2 has been produced by diazo-coupling reaction of p-nitroaniline with vanillin at 0-5 Celcius degree. Vanillin-hydrazone derivative, (2-methoxy-4-phenylhydrazone)phenol (1) was also synthesized from vanillin and phenylhydrazine. Compounds 1, 2, and 3 were elucidated by spectroscopic methods to determine their structures. Synthesis of compound 1, 2, and 3 gave 70.25; 68.22 and 38.46% in yield respectively. The result showed that compounds 1, 2, and 3 gave a bathochromic shift as solvent polarity increased (acetone, acetonitrile, and DMSO). This study also revealed that compounds 1, 2, and 3 can be used as colorimetric anion sensor that easily recognized by naked eye. Compound 1 showed good selectivity but low sensitivity for cyanide anion. Compound 2 in acetone gave selectivity for fluoride, cyanide, and acetate over chloride, bromide, iodide, and dihydrogen phosphate with limit of detection of acetate was 0.1 mM. Compound 3 in DMSO was selective for fluoride, cyanide, and acetate with ability to detect cyanide in 0.2 mM. Compound 3 in mixture of DMSO-H2O (9:1) was reduced the ability to recognize anion by naked eye.

Kata Kunci : vanilin, azo-hidrazon, sensor anion, kolorimetri