Synthesis, effect of substituents and antimicrobial activities of some 4-bromophenyl chalcones

Available online at www.worldscientificnews.com WSN 54 (2016) 132-152 EISSN 2392-2192 Synthesis, effect of substituents and antimicrobial activities of some 4-bromophenyl chalcones S. Vijayakumar1, G. Vanangamudi1 and G. Thirunarayanan2,* 1 PG and Research Department of Chemistry, Government Arts College, C-Mutlur - 608102, Chidambaram, India 2 Department of Chemistry, Annamalai University, Annamalainagar - 608002, India *E-mail address: , ABSTRACT Elven (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2-propen-1-ones are formed using sodium hydroxide catalyzed Aldol condensation between 4-bromoacetophenone and substituted benzaldehyde. The production of these chalcone compounds are above 90%. These α, β unsaturated ketones were specified by their physical constants and spectral data (UV, IR, 1H and 13C-NMR). Hammett substituted constants (σ, σ+, σI & σR and F and R parameters have been used for correlating the spectral values of these α, β unsaturated ketones by using single and multi-linear regression analysis. The impacts of substituents on the spectral data have been known on statistical analysis. By using BauerKirby method the anti-microbial activities of these (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2propen-1-ones compounds are estimated. Keywords: (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2-propen-1-ones; UV spectra; IR spectra; NMR spectra; Substituent effects; Antimicrobial activities 1. INTRODUCTION Chalcones are α, β unsaturated ketones, possess methylene structural moieties and they belongs to biomolecules. α, β unsaturated ketones of the categories alkyl-alkyl, alkyl-aryl and World Scientific News 54 (2016) 132-152 aryl-aryl have been synthesized [1] and extracted from natural plants [2] by organic chemists. For synthesizing chalcones various methods are available such as Aldol, Crossed-Aldol, Claisen-Schmidt, Knovenagal reactions, Greener methods-Grinding of reactants, solvent free and oxides of nanoparticles with microwave irradiation. Solvent free Aldol condensation and Crossed-Aldol condensation [3-5] assisted by microwave were useful for synthesis of carbonyl compounds. Many catalyst were used for proceedings the chalcones synthesis reactions namely, Ethanol-NaOH [6], Methanol-KOH [7], EtOH-potassium hydroxide [8], Magnesium chloride [5], silica-H2SO4 [9], anhydrous ZnCl2 [10], clay [11], Hydrotalcite [12], ground chemistry catalysts-grinding the reactants with NaOH [13], aqueous alkali in lower temperature [14], solid sulphonic acid from bamboo [15], Ba(OH)2 [16], anhydrous Na2CO3 [17], microwave irradiation preparation [18], fly-ash: H2O [19], fly-ash: H2SO4 [20], fly-ash: PTS [21], NaOHCTABr [22], SiO2-H3PO4 [23], SOCl2 [24] and sulfated titania [25]. For prediction of ground state equilibration such s-cis and s-trans conformers the spectral data of these E-chalcones were used. The effects of substituent of the UV absorption maximum (λmax, nm), IR group frequencies (ν, cm-1) and NMR chemical shift (δ, ppm) values of α, β-proton and carbons of 4-ethoxyphenyl chalcones compounds and benzimidazole chalcones compounds have been studied detail by Janaki et al., [23]. In their studies, spectral data were observed satisfactory and correlated well with Hammett substituent constants (σ, σ+, σI & σR) and F and R parameters. The α, β unsaturated carbonyl compounds, possess various multipronged activities such as antimicrobial [26], antidepressants [27], antiplosmodial [28], anti-aids [29] and insect antifeedant activities [13,22]. A list of elven (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2propen-1-ones synthesized, studied the spectral correlations and evaluate to the antimicrobial activities against micro species using Bauer-Kirby [30] method. 2. EXPERIMENTAL 2. 1. General All used chemicals were purchased from Sigma-Aldrich and E-Merck chemical companies. Melting points of all α, β unsaturated ketone compounds were determined in open glass capillaries on Mettler FP51 melting point apparatus.The ELICO BL 222 ultraviolet spectrophotometer was utilized for recording the absorption maxima (λmax, nm), of all α, β unsaturated ketone compounds in spectral grade methyl alcohol. Infrared spectra (KBr, 4000400 cm-1) were recorded AVATAR-300 Fourier transform spectrophotometer. Bruker AV400 NMR spectrometer was used for recording NMR spectra operating at 500 MHz for 1H spectra and 125.46 MHz for 13C spectra in CDCl3 solvent using TMS as internal standard. 2. 3. Synthesis of (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2-propen-1-ones Eqimolar quantities of 4-bromoacetophenone (1mmol) and benzaldehyde (1mmol) were taken in a 250 ml conical flask and mixed with sodium hydroxide (0.5 g) in 10 mL of absolute ethanol for 1 hr [31] and it is shown in (Scheme 1). The resultant mixture was cooled at room temperature. Final product obtained was a pale yellow solid. This crude product was recrystallization by ethanol. Which result in glittering pale yellow. The physical constant values and analytical data of all (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2-propen-1- -133- World Scientific News 54 (2016) 132-152 ones were presented in Table 1. The ultraviolet, infrared and NMR spectroscopic data of synthesized (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2-propen-1-ones were tabulated in Table 2. Scheme 1. Synthesis of (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2-propen-1-ones. Table 1. The physical constant values and analytical data of (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2-propen-1-ones. Entry X M.F. M.W. Yield (%) m.p. (°C) 1 H C15H11BrO 287 85 155 (155-157) [31] 2 2-Cl C15H10BrOCl 321 84 218 3 3-Cl C15H10BrOCl 321 86 120 4 4-Cl C15H10BrOCl 321 86 115 5 4-F C15H10BrOF 305 83 141 6 2-OH C15H11BrO2 303 80 108 7 2-OCH3 C16H13BrO2 321 84 141 8 4-OCH3 C16H13BrO2 321 85 197 9 4-CH3 C16H13BrO 305 86 148 10 3-NO2 C15H10BrO3N 332 82 128 11 4-NO2 C15H10BrO3N 332 80 136 -134- World Scientific News 54 (2016) 132-152 Table 2. The ultraviolet absorption maxima (λmax, nm), infrared absorptions (ν, cm-1) and NMR chemical shifts (δ, ppm) of substituted (E)-1-(4-bromophenyl)-3-(substituted phenyl)-2propen-1-ones. IR (ν, cm-1) Entry X UV (λmax, nm) 1 H 314.0 1656.85 1593.13 1178.51 761.88 1029.99 2 2-Cl 264.0 1658.78 1593.13 1209.37 771.53 1072.42 3 3-Cl 304.0 1658.78 1589.34 1207.44 771.53 1076.28 4 4-Cl 316.0 1685.79 1579.70 1178.54 713.66 1066.64 5 4-F 314.0 1675.79 1589.70 1176.54 715.66 1063.64 6 2-OH 264.0 1655.85 1583.20 1113.00 716.88 1078.56 7 2-OCH3 347.0 1653.00 1589.34 1159.22 738.74 1070.49 8 4-OCH3 347.0 1656.85 1593.20 1111.00 761.88 1068.56 9 4- CH3 325.0 1654.92 1589.34 1170.79 738.74 1068.56 10 3-NO2 259.0 1678.07 1583.56 1176.58 736.81 1072.42 11 4-NO2 259.0 1683.86 1585.49 1118.71 763.81 1062.78 H NMR (δ, ppm) 13 IR (ν, cm-1) Entry CO(s-cis) CO(s-trans) CHip CHop C (...truncated)