Synthesis and Hammett spectral correlation studies of some substituted cyanopyridine compounds

Available online at www.worldscientificnews.com WSN 80 (2017) 239-255 EISSN 2392-2192 Synthesis and Hammett spectral correlation studies of some substituted cyanopyridine compounds R. Arulkumaran1, V. Manikandan1, G. Thirunarayanan2,* 1 PG & Research Department of Chemistry, Government Arts College, C-Mutlur, Chidambaram - 608102, India 2 Department of Chemistry, Annamalai University, Annamalainagar - 608002, India *E-mail address: , ABSTRACT About ten substituted cyanopyridine compounds have been synthesized and the purities of these pyridines were examined with their physical constants, analytical and spectroscopic data provided in the literature. They are characteristic infrared stretches and NMR chemical shifts were assigned and they are correlated with Hammett substituent constants using single and multi-linear regression analysis. From the results, the effect of substituents on the spectral data of cyanopyridine has been discussed. Keywords: Substituted cyanopyridine, IR and NMR spectra, Hammett constants, Single and multicorrelation analysis 1. INTRODUCTION Pyridines with different functional groups are exhibit wide range of applications in the field of medicinal chemistry, agriculture and dye preparing field. And also, pyridine is the parent of the series of compounds that is important in pharmaceutical and industrial chemistry. Although many substituted pyridine compounds like other heterocyclic compounds are synthesized with their functional group present from heterocyclic compounds. World Scientific News 80 (2017) 239-255 The simple pyridine compounds are prepared by the cyclization of aliphatic raw materials. Many naturally occurring and synthetic compounds containing the cyanopyridine and cyanopyran scaffold possess interesting pharmacological character in nature [1]. Pyridine containing liquid crystalline compounds has also been prepared using several other methods [2-7]. Among a wide range of pyridines, 3-cyanopyridines [8] acquired a special attention due to their wide range of therapeutic activities. Most pyridine derivatives are prepared by manipulation of pyridine and its simple homologues in a manner similar to chemistry of the benzenoid chemistry. Molecules containing pyridine always have grave importance in chemistry as well as in biology. The pyridine substructure is one of the most prevalent heterocyclic molecular frameworks found in natural products, pharmaceuticals, vitamins and functional materials [912]. The simple pyridine compounds are prepared by the cyclization of aliphatic raw materials. Interests in the synthesis of multicyclic pyridine containing compounds have increased in recent years because of their wide range of pharmacological activities. Cyanopyridine derivatives have been used as herbicides [13], for enrichment of cereals [14], for regulation of arterial pressure [15] and cholesterol levels in blood [16]. The cyanopyridine derivatives widely used in the fields of feed additive, food additive and pharmaceuticals. The enzymatic synthesis of nicotinamide from 3-cyanopyridine catalyzed by nitrile hydratase has the advantages of high yield and little by products. In recent years synthesis of cyanopyran and cyanopyridine compounds prepared from various aryl chalcones. And also cyanopyridine compounds are used to prepare cyanopyridine based conjugated polymers. Within the above view, some information only available in literature in the past for synthesis, spectral correlation analysis of the title compounds. Therefore the authors have taken efforts for the synthesis of cyanopyridine to study the quantitative structure activity relationships by spectral correlation through Hammett equation with their Infra-Red and NMR spectral data. 2. EXPERIMENTAL 2. 1. Materials and Systematic methods All chemicals were used and purchased from Sigma-Aldrich chemical company Bangalore. All synthesized cyanopyridine compounds melting points are observed from uncorrected Suntex melting point apparatus using open glass capillaries. The above cyanopyridine compounds for Infrared spectra (KBr, 4000-400 cm-1) have been recorded on AVATAR-300 FT-IR spectrophotometer. BRUKER-400MHz NMR spectrometers has been operated for recording 1H and 13C spectra in CDCl3 solvent using internal standard as TMS. 2. 2. General procedure for synthesis of cyanopyridine compounds. According to the literature procedure[17], the cyanopyridine derivatives were prepared and their purities were examined with their physical constants, analytical and spectroscopic data provided. The substituted cyanopyridine structure was shown in Figure 1. -240- World Scientific News 80 (2017) 239-255 Figure 1. Substituted cyanopyridines The synthesized substituted cyanopyridine compounds have been characterized by their physical constants, elemental analysis and spectral data. The physical constants, analytical and micro analysis data of these substituted cyanopyridine compounds are shown in Table 1. The spectral data of synthesized substituted cyanopyridine compounds are shown in Table 2. Table 1. Physical constants, yields and analytical data of substituted cyanopyridine compounds Entry X M. F. M.W. Yield (%) M.p. (ºC) 1 H C31H19N4Cl 482.96 97 162-163 2 4-NH2 C31H20N5Cl 497.98 93 208-209 3 4-Br C31H18N4ClBr 561.86 91 214-215 4 4-Cl C31H18N4Cl2 517.41 94 234-235 5 3-OH C31H19N4ClO 498.96 87 235-236 6 4-OH C31H19N4ClO 498.96 91 229-230 -241- Found (Calcd.) (%) C H N 77.01 (77.09) 74.05 (74.17) 65.86 (66.27) 71.14 (71.96) 74.02 (74.62) 74.14 (74.62) 3.86 (3.97) 4.00 (4.05) 3.16 (3.23) 3.06 (3.51) 3.26 (3.84) 3.44 (3.84) 10.98 (11.60) 13.99 (14.06) 9.45 (9.97) 10.53 (10.83) 10.98 (11.23) 11.03 (11.23) World Scientific News 80 (2017) 239-255 7 4-OCH3 C32H21N4ClO 512.99 96 221-222 8 4-CH3 C32H21N4Cl 496.99 92 180-181 9 3-NO2 C31H18N5ClO2 527.96 89 201-202 10 4-NO2 C31H18N5ClO2 527.96 90 187-188 74.06 (74.92) 87.02 (77.33) 70.24 (70.52) 70.28 (70.52) 3.94 (4.13) 4.14 (4.26) 3.26 (3.44) 3.32 (3.44) 10.08 (10.92) 11.02 (11.27) 13.04 (13.26) 13.18 (13.26) Table 2. The infrared absorptions (ʋ, cm-1) and NMR chemical shifts (δ ppm) spectral data of substituted cyanopyridine compounds. NMR (δ, ppm) IR  (cm ) -1 Entry 1 X 13 H C NH2 C=N CN NH2 CN C-Cl Cipso 1 H 3309.22 1660.23 2218.39 3.494 163.15 114.07 115.70 2 4-NH2 3318.31 1660.77 2212.74 3.468 163.50 116.28 116.74 3 4-Br 3332.09 1660.24 2198.45 3.402 165.48 118.02 118.27 4 4-Cl 3319.42 1660.97 2205.61 3.450 166.20 118.01 119.14 5 3-OH 3306.55 1660.29 2226.78 3.462 162.08 116.68 117.62 6 4-OH 3309.22 1660.27 2207.86 3.476 163.14 117.24 118.40 7 4-OCH3 3313.22 1660.77 2195.07 3.836 162.10 112.05 114.54 8 4-CH3 3347.63 1660.72 2201.23 3.442 162.14 117.02 118.50 9 3-NO2 3313.33 1660.47 2201.23 3.484 164.72 115.73 116.23 10 4-NO2 3321.26 1660.27 2208.31 3.446 1 (...truncated)