Solvent Free Synthesis of Chalcones and their Antibacterial Activities

Journal of Chemistry, Jun 2019

The solvent free synthesis of six chalcones was carried out by grinding the piperanal and the acetophenone (unsubstituted, 4-methyl, 4-methoxy, 4-bromo, 4-nitro, 3-chloro) in the presence of solid sodium hydroxide with a mortar and pestle. In general, the chalcones were obtained in high yield and high purity. Minor quantities of Ketol and Michael addition product were easily removed by recrystallization. The result indicates a correlation between the success of the solvent-free synthesis and melting point of the chalcone. Chalcone with relatively high melting points (higher than 80°C) were obtained in high yields. The two chalcones that could not be produced in good yields were having relatively low melting points. They have been screened for their antibacterial activity against Gram positive and Gram negative bacteria.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

http://downloads.hindawi.com/journals/jchem/2005/294094.pdf

Solvent Free Synthesis of Chalcones and their Antibacterial Activities

CODEN ECJHAO E-Journal of Chemistry Vol. 2 Solvent Free Synthesis of Chalcones and their Antibacterial Activities RAJENDRA K. SAINI 1 AMIT S.CHOUDHARY 1 YOGESH.C. JOSHI 1 P. JOSHI 0 1 0 S.S. Jain Subodh P.G. College , Jaipur-302004, Rajasthan 1 Department of Chemistry, University of Rajasthan , Jaipur - 302004 , India The solvent free synthesis of six chalcones was carried out by grinding the piperanal and the acetophenone (unsubstituted, 4-methyl, 4-methoxy, 4-bromo, 4-nitro, 3-chloro) in the presence of solid sodium hydroxide with a mortar and pestle. In general, the chalcones were obtained in high yield and high purity. Minor quantities of Ketol and Michael addition product were easily removed by recrystallization. The result indicates a correlation between the success of the solvent-free synthesis and melting point of the chalcone. Chalcone with relatively high melting points (higher than 80?C) were obtained in high yields. The two chalcones that could not be produced in good yields were having relatively low melting points. They have been screened for their antibacterial activity against Gram positive and Gram negative bacteria. Solvent free synthesis; Chalcone; Antibacterial activity Introduction The chalcones possess an a,b-unsaturated grouping in the molecules. The structural assignment of these chalcones was based on elemental analysis, IR and NMR spectral data. The antibacterial activity of these chalcones has been studied by cup-plate method9, 10, 11. Experimental Melting points are uncorrected. The IR spectra were recorded in KBr disc on a Nicolet Megna-FT-IR 550 spectrometer, 1H NMR were recorded on model DRX 300 at 300.13 in CDCl3 / DMSO-d6 using TMS as internal standard. The purity of the newly synthesized compounds was checked by TLC. Solvent free synthesis of chalcone The solvent free synthesis of chalcones was carried out by grinding the piperanol (0.05 mol) and acetophenone derivative (0.05 mol) in presence of solid sodium hydroxide (0.05 mol): petroleum ether (1:1) yielded the crystalline product. Purity of the compounds was checked by TLC using CHCl3 as mobile phase. Spectral studies The IR spectra showed a characteristic bands at 1645-1635 (C=O), 1580-1570 cm?1 (C=C), asymmetrical C-O-C stretching band around 1200-1275 cm?1 and symmetrical stretching at 1020-1075 cm?1. In 1H NMR, a singlet was observed at d 5.98-6.01 due to dioxymethylene group. Doublet at 7.82 for a-proton and 8.02 for b-proton in chalcones. A complicated pattern in the aromatic region at d 6.9-8.2 showed the presence of seven aromatic protons. Elemental analysis and 1H NMR data of the title compounds are given in Table 1 and 2 respectively. O O O O X C CH3 O + OHC NaOH (solid) X C CH CH O (1a-e) X= H, CH3, OCH3, Br, NO2, Cl The compounds were screened for antibacterial activity by cup-plate method at a concentration of 50 m ml?1 against gram-positive and gram-negative bacteria viz. Staphylococcus aureus, Escherichia coli, Streptococcus viridiaus and K. salmonilla using their dimethylformamide solution. The activity was compared with chloromycetin. The result (Table 3) showed that most of the chalcones possess moderate to good activity (zone of inhibition, 10-15 mm). Some of the compounds containing chloro / bromo substituents were active while other possessed moderate or feeble activity against the bacteria. Solvent Free Synthesis of Chalcones Conclusion Solvent free synthesis of chalcones was a novel method for synthesis of chalcones. The chalcones were obtained in high yield and high purity. The result indicates a correlation between the success of solvent free synthesis and melting point of the chalcones. Chalcone with relatively high melting point were obtained in high yields of these, the chalcones 1a-1f were tested for their antibacterial activity. The result showes that chalcones, containing chloro/bromo substituents were active while other possessed moderate activity against bacterias. Acknowledgement Authors are thankful to Head, Department of Chemistry, University of Rajasthan, Jaipur for providing laboratory facilities. Authors are also thankful to Central Drug Research Institute, Lucknow for providing spectral data. One of us Rajendra Kumar Saini is thankful to the CSIR, New Delhi for the award of Junior Research Fellowship. 4. 5. 6. 7. 8. 9. 10. 11. International Journal of Medicinal Chemistry Hindawi Publishing Corporation ht p:/ www.hindawi.com International Hindawi Publishing Corporation ht p:/ www.hindawi.com International Journal of Photoenergy International Journal of Analytical Chemistry Advances in Physical Chemistry Hindawi Publishing Corporation Hindawi Publishing Corporation ht p:/ www.hindawi.com International Journal of Carbohydrate Chemistry Hindawi Publishing Corporation ht p:/ www.hindawi.com The Scientiifc World Journal Hindawi Publishing Corporation ht p:/ www.hindawi.com Submit your manuscr ipts http://www.hindawi.com Journal of Spectroscopy Hindawi Publishing Corporation ht p:/ www.hindawi.com Inorganic Chemistry Journal of Applied Chemistry organic Hindawi Publishing Corporation ht p:/ www.hindawi.com Theoretical Chemistry Journal of Hindawi Publishing Corporation ht p:/ www.hindawi.com Chromato Journal of International Journal of


This is a preview of a remote PDF: http://downloads.hindawi.com/journals/jchem/2005/294094.pdf

K. Rajendra K. Saini, S. Amit Choudhary, Yogesh. C. Joshi, P. Joshi. Solvent Free Synthesis of Chalcones and their Antibacterial Activities, Journal of Chemistry, DOI: 10.1155/2005/294094