R.I. Lerrick et al. ISBN 978-979-18962-0-7 Proceeding of The International Seminar on Chemistry 2008 (pp. 194-198) Jatinangor, 30-31 October 2008 The Synthesis of 4-Hydroxy-3-Methoxybenzonitrile from Vanillin: a Precursor of Synthesis of 3′′-methoxydaidzein Reinner Ishaq Lerrick1*, Bambang Purwono2, Sabirin Matsjeh2 1 Chemistry Department, Faculty of Sciences and Techniques, Nusa Cendana University, Jl. Adi Sutjipto Kampus Baru Penfui Kupang NTT 2 Chemistry Department, Faculty of Mathematics and Natural Sciences, Gadjah Mada University, Bulak Sumur, Yogyakarta * Corresponding author, tel: +6285239025326, email: i_lerrick@yahoo.com.sg Abstract Isoflavone and its derivates have attracted researchers’ interest in recent year. According to the esterogen like properties, daidzein and others isoflavone derivates have been used as medicine in treatment of degenerative diseases such as arteriosclerosis, hot flash symptoms, osteoporosis and even for breast and prostate cancer. Daidzein has become as a molecular model in order to develop new more active drugs. Due to its close chemical structure similarity to vanillin, based on retro-synthesis approach, vanillin could be used as starting material for synthesis of 3′-methoxydaidzein i.e. as 4hydroxy-3-methoxybenzonitrile. The synthesis was carried out through two steps of reaction i.e. reduction of vanillin becoming vanillyl alcohol with NaBH4 then halogenations which was followed by nitrilization of the product with PBr3 and KCN, respectively. Yields of synthesis were 83 % of white crystal of vanillyl alcohol and 36 % of yellow crystal of 4-hydroxy-3-methoxybenzonitrile. Keywords: isoflavone, 3′-methoxydaidzein, vanillin, 4-hydroxy-3-methoxybenzonitrile benzoin (2) as the important intermediate precursor. This synthesis path needs a benzylcarboxylate (3) or a benzonitrile (4) derivates as the starting material [7]. However, benzonitrile step of reaction (HoubenHoesch reaction) is the favour one according to shorter step of reaction and even can be carried out in one-pot reaction [8]. Vanillin (5) which its structure resembles to benzonitrile (4), can be used as raw material in order to synthesis one of daidzein derivates i.e. 3′methoxydaidzein (8). Hydroxyl group which has oriented at para position through aldehyde, an ease converting group, makes vanillin becomes favourable material [9]. Furthermore, the present of additional methoxy group hopes increasing the anti degenerative effect as donating effect of that group. Introduction Isoflavones, which mostly contain in cereals (Leguminoceae) especially in soy bean, have been proven experimentally showing biological activities related to degenerative diseases such as arteriosclerosis, breast and prostate cancer [1-4], and reduced hot flash symptoms suffered by women menopausal phase. Furthermore, synthetic form of daidzein (1), one of major constituent of isoflavone, has been used as medicine in osteoporosis treatment [5-6]. Daidzein has also used as molecular model for developing new more active compounds in recent years. Synthesis of new daidzein derivates as well as all isoflavones synthesis involves o-hydroxydeoxy HO O OH HO O OH O OH 2 1 HO NC OH 4 Figure 1. Retrosynthesis of Daidzein 194 O OH 3 R.I. Lerrick et al. Proceeding of The International Seminar on Chemistry 2008 (pp. 194-198) Jatinangor, 30-31 October 2008 H O NC OH NaBH4 HO (1) PBr3-ether methanol OMe OMe OH OH 5 6 (2) KCN, Tween 80 Benzene O OMe OMe OH 7 O OH 8 Figure 2. The Synthesis Steps of Synthesis of 3′-methoxydaidzein In this research, there were two steps of aldehyde conversion into the target material. The synthesis covered reduction of aldehyde using sodium borohydrate (6) and brominating of the alcohol which was followed with nitrilization of the product becoming 4-hydroxy-3-methoxybenzonitrile (7). Results and Discussion Materials and Method Synthesis of vanillyl alcohol Materials Vanillin, NaBH4, KCN, PBr3, methanol, dichloromethane, ether, benzene, Na2SO4, and Tween 80. All reagents utilized were pro analysis quality from Merck. Direct reduction of vanillin produce 63% of white crystal (m.p. = 112-113 oC, lit. = 112-115 oC) [10]. The gas chromatogram shows that the product is high pure. extracted with 3 x 20 ml of benzene. The organic layer was collected and was dried using Na2SO4. The organic solvent was evaporated and the product was analysed using FT-IR and GC-MS. Procedure Synthesis of vanillyl alcohol Vanillin (0.9 g, 6.0 mmol) was putted into 100 ml of Erlenmeyer flask and diluted with 50 ml of methanol. Sodium borohydrate (NaBH4) (0.3 g, 8.0 mmol) was added into the solution while shaking. The solution was stirred for over night. Methanol was evaporated using Büchii evaporator and the white residue was diluted with 50 ml of water and then extracted using 3 x 20 ml of dichloromethane. The organic layer was collected and dried over Na2SO4. The solvent was removed in vaccuo and the white crystal was determined its melting point. Structure analysis was characterized using FT-IR, 1H-NMR and GC-MS. Figure 3. Gas Chromatogram of Vanillyl Alcohol Analysis of that white crystal using FT-IR gives several characteristic absorptions. Lack of the aldehyde absorption i.e. at 1730 cm-1 and the two peaks at around 2850 and 2750 cm-1 indicates that the product is no longer an aldehyde. Moreover, the presence of strong intensity peak at 1434.9 cm-1 corresponded to methylene (-CH2-) group strengthens that vanillin has been reduced. Other functional groups that appear are hydroxyl at 3440.8 cm-1, aromatic at 1604.7 and 1512.1 cm-1, ether at ca. 1265.2 -1126.4 cm-1 and methyl at 1373.2 cm-1. Further analysis using 1 H-NMR is showed in Figure 5. According to the spectrum, there are six magnetic types of proton represented by six peaks. Peak A is hydroxyl proton due to its singlet and one proton integration. Peak B belongs to 3 protons of aromatic laid in δ = 6-7 ppm. Besides that, peak C, D and E correspond to 2 singlet proton of methylen (CH2-), 3 singlet proton of methyl (-CH3) and 1 singlet proton of benzyl hydroxyl which absorbs more up field then phenolic proton (6.5 - 8.5 ppm), respectively. Synthesis of 4-hydroxy-3-methoxybenzonitrile Vanillyl alcohol (0.2 g, 1.2 mmol) in 15 ml of ether was placed in ice bath until the temperature -5 o C then added 0.5 g (1.8 mmol) of potassium bromide with stirring drop wise. Then stood the mixing for 2 hours and further for 2 hours at room temperature. The solution was poured 5 ml of cooled water and then transferred the solution into separator funnel. The solution then extracted with ether (3 x 10 ml). The combine organic layers were collected and dried with sodium sulphate. The solvent was evaporated and then collected as an oily product. Vanillyl bromide was immediately added potassium cyanide (0.16 g, 2.5 mmol) solution in 5 ml of water, 5 ml of benzene and 0.1 g of Tween 80. The solution then refluxed for 6 hours. Into separatory funnel, the cooled solution is poured was then 195 R.I. Lerrick et al. Proceeding of The International Seminar on Chemistry 2008 (pp. 194-198) Jatinangor, 30-31 October 2008 Wavenumber (1/cm) Figure 4 FT-IR spectrum of vanillin reduction product (KBr-Disc) Figure 5. 1H-NMR of Vanillyl Alcohol m/z Figure 6. Mass spectrum of Vanillyl Alcohol 196 Proceeding of The International Seminar on Chemistry 2008 (pp. 194-198) Jatinangor, 30-31 October 2008 Intensity R.I. Lerrick et al. Time (min) %T Figure 7. Gas chromatogram of nitrilization product Wavenumber (1/cm) Figure 8. FT-IR spectrum of nitrilization product (KBr-Disc) m/z Figure 9. Mass spectrum of nitrilization product 197 R.I. Lerrick et al. Proceeding of The International Seminar on Chemistry 2008 (pp. 194-198) Jatinangor, 30-31 October 2008 According to FT-IR and NMR spectrum, the product of vanillin reduction is vanillyl alcohol. This is proved by the mass spectrometer analysis. 2. Lovati, M. R., Manzoni, C., Gianazza, R., Arnoldi, A., Korowska, E., Carroll, K. K., Sirtori, C. R., 2000, Soy Protein Peptide Regulate Cholesterol Homeostasis in Hep G2 Cells, The Journal of Nutrition, 2543-2549. 3. Jane, L. W. L., Karl, E. A., James, J. G., Fortune, K., and Manubai, N., 2000, Decreased Ovarian Hormones during a soy diets: Implication for Breast Cancer Prevention, Journal of Cancer Research, 60, 4112-4121. 4. Xu, X., Alison, M., Duncan, Karry, E. W., and Mindy, S. K., 2000, Soy Consumption Alters Endegenous Esterogen Metabolism in Postmenopousal Women, Journal of Cancer Epidemiology, Biomarkers and Preventions, 9, 781-786. 5. Ikegami, S., Tousen, Y., Ishimi, Y., Umegaki, K., and Nakashima, Y., 2006, Possible Adverse Effects of Soy Isoflavone Mixture on Pregnant and Lactating Rats and Their Suckling Pups, Journal of Health Science, 52(5),558-567. 6. Alekel, D. L., Alyson, St G., Charles, T. P., Kathy, B. H., Jeanne, W. S., and Toshiya, T., 2000, Isoflavone-rich soy protein isolate attenuates bone loss in the lumbar spine of perimenopausal women, American Journal of Clinical Nutrition, 72,844-852. 7. Whalley, J. L., Mark, F. O., and Nigel, P. B., 2000, Synthesis of [4-13C]-Isoflavanoid Phytoesterogens, Tetrahedron, 56, 455-460. 8. Faria, T. J., Silva, L. G. F., Filho, J. D. S., Chiari, E., and Oliveira, A. B., 2005, Synthesis and Tripanocydal Activity of 7,2’-Dioxygenated Isoflavones and Oxypropanolamine Derivatives, J. Braz. Chem. Soc., 16, 6B, 1415-1419. 9. Lerrick, R. I., 2008, Study of Hydroxyl Protection Effect to Reduction of Vanillin Becoming a Useful Starting Material for Synthesis of One Daidzein Derivates, in Proceeding of the XVIII National Chemistry Seminar, Gadjah Mada University, Yogyakarta. 10.Budavari, S., 1989, The Merck Index, an Encyclopedia of Chemicals, Drugs and Biologicals, 7th ed, John Wiley and Sons Inc., New York. Synthesis of 4-Hydroxy-3-methoxybenzonitrile Synthesis of 4-hydroxy-3-methoxybenzonitrile is carried out in two series of reaction i.e. bromination of vanillyl alcohol and nitrilization the product using NaCN. Bromination reaction produced high yield (98%) of oily product whereas nitrilization only gives 36% of yellow crystal. The malting point of the product is 55-57 oC corresponded to literature i.e. at 56-57oC [10]. Analysis of nitrilization product using FT-IR is shown in Figure 8. According to the spectrum, the presence of medium absorption at 2252.86 cm-1 caused of –C ≡ N stretch indicates strongly that the product is a cyanide compound. This closes to nitrile characteristic absorption, which is around 2200-2300 cm-1 in medium to weak intensity. Other functional groups that still present are alkene’s system which belongs to substituted aromatic system, methyl and methylene, hydroxyl and ether group. Further more, analysis of that yellow product with mass spectrometer justifies that the product is 4hydroxy-3-methoxybenzonitrile due to its M+ and fragmentation pattern. Conclusions The series of synthesis using vanillin as a raw material in this research yields: 83 % of vanillyl alcohol, 36 % of 4-hydroxy-3-methoxybenzonitrile. Acknowledgements This research is a very small part of big series of synthesis funded by Indonesian Directorate General of Higher Education, DIKTI. References 1. Winarsi, H., 2005, Isoflavon Berbagai Sumber, Sifat dan Manfaatnya Pada Penyakit Degenartif, Gadjah Mada University Press, Yogyakarta, 3. 198