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The International Journal Of Science & Technoledge (ISSN 2321 – 919X) THE INTERNATIONAL JOURNAL OF
SCIENCE & TECHNOLEDGE
Synthesis and Biological Evaluation of
Some New Pyrazoline Derivatives of Vanillin Analogue
V. R. Dangar
Department of Chemistry, Kamani Science College, Amreli, Gujarat, India J. V. Dodia
Department of Chemistry, Kamani Sc ience College, Amreli, Gujarat, India V. R. Shah
Department of Chemistry, Kamani Sc ience College, Amreli, Gujarat, India Abstract:
Some new 3-Aryl-5-[4’-(o-chlorobenzyloxy)-3’-methoxypheny l]-4,-5-dihydro-1H-pyrazoles were prepared. All the prepared compounds were characterized by their spectral (I.R., N.M.R.,Mass) data and screened for their antimicrobial activities.
Key words: Chalcone, Pyrazoline , antimicrobial activities

1. Introduction
The chemistry of chalcones1-3 containing an active keto-ethylenic linkage has been assumed important because of their versatility
in the synthesis of many heterocyclic compounds. The presence of reactive α ,β –unsaturated keto function in chalcones is found
to be responsible for their antibacterial4-7 and antifungal activity8-9. Chalcones constitute an important group of natural products
and some of them possess a wide range of biological activity such as antibacterial, antitubercular10-11, anticancer12-13, antitumour14-
16 etc. Pyrazoline derivative17-20 have been found to possess a wide range of therapeutic activity such as anticonvulsant21-22,
analgesic23-24, antibacterial, antifungal, anticancer, etc.
Chalcones and pyrazolines have proved to be the most useful framework for biological activities, Both have attracted attention of
medicinal chemists for both with regard to heterocyclic chemistry and the pharmacological activities associated with them. This
inspired us to synthesize 1-Aryl-3-[4’-(o- chlorobenzyloxy) -3’-methoxyphenyl] -propenones (1a-l) and 3-Aryl-5-[4’-(o-
chlorobenzyloxy) -3’-methoxyphenyl] -4, -5-dihydro-1H-pyrazoles (2a-l).
The structure of synthesized compounds was assigned based on Elemental analysis, I.R. 1H-NMR and Mass spectral data. The
antimicrobial activity was assayed by using the cup-plate agar diffusion method 25 by measuring the zone of inhibition in mm. All
the compounds were screened in vitro for their antimicrobial activities26 against varieties of bacterial strains such Staphylococcus
aureus, Bacillus subtillis, Escherichia coli, Proteus vulgaris and fungi Aspergillus niger at 40 μg concentration. Standard drugs
like Ampicillin, Amoxicillin, Norfloxacin, Benzyl penicillin and Griseofulvin were used for comparison purpose (Table-1).
2. Results and Discussion
The synthesis of 1-Aryl-3-[4’-(o- chlorobenzyloxy )-3’-methoxyphenyl]-propenones (1a-l) and 3-Aryl-5-[4’-(o-
chlorobenzyloxy)-3’-methoxyphenyl]-4,-5-dihydro-1H-pyrazoles (2a-l) was carried out in two steps, first by the condensation of
4-[(2-chlorobenzyl)oxy]-3-methoxy benzaldehyde (1) with different aromatic acetophenone by Claisen-shmidt condensation in
presence base catalyst to give chalcone derivatives (1a-l), which in next step were refluxed with hydrazine hydrate to yield
pyrazoline derivatives ( 2a-l). (scheme-1).
The formulas of the selected compounds were confirmed by the elemental analysis and their structures were determined by IR ,1
H-NMR , and mass spectral data.
3. Antibacterial Activity
It has been observed from the microbiological data that all compounds (1a-l) and (2a-l) were found to be mild to moderately
active against Gram positive and Gram negative bacterial strains. How ever the maximum activity was observed in compounds
(1a),(1i),(2c),(2g) against S.aureus. The significant activity was observed in compounds (1b),(1e),(2b),(2f) against B.subtillis. The
maximum activity was displayed by the compounds (1e),(1j),(2b),(2d), against E.coli. The compounds (1c),(1h),(2f), and (2g)
were comparatively more effective against P.vulgaris.
The International Journal Of Science & Technoledge (ISSN 2321 – 919X) 4. Antifungal Activity
The antifungal data revealed that compounds were least toxic to the fungal strain. However mild activity was shown by the
compounds (1g),(1h),(1l),(2c),(2e),(2k), against A.niger.
The antibacterial activity was compared with standard drug viz. Ampicillin, Amoxicillin, Norfloxacin, Penicillin and antifungal
activity was compared with standard drug viz. Griseofulvin.
5. Experimental Section
Melting points were taken in open capillary tubes are uncorrected. IR spectra (cm-1) were recorded on Shimadzu-435-IR
Spectrophotometer and , 1H-NMR spectra on Bruker spectrometer (300MHz) using TMS as an internal standard, chemical shift in
δ ppm.
General procedure for the preparation of 1-Aryl-3-[4’-(o-chlorobenzyloxy )-3’-methoxyphenyl]-propenones (1a-l) :
Take a mixture of 4-[(2-chlorobenzyl)oxy]-3-methoxy benzaldehyde (1) (0.01M) and 4-methoxy acetophenone (0.01) in
methanol, add a NaOH (0.002M) to the reaction mixture . The reaction mixture was magnetically stirred for 12 hrs and then left
overnight. After it was pour over ice and neutralised with dil.HCl and ethanol is added for crystallisation.
4-[(2-chlorobenzyl)oxy]-3-methoxy benzaldehyde (1) :
Yield 90%, m.p. 58 0C; IR(KBr) : ν 2922 (-CHO), 1260 (-OCH3) ,640 (-C-Cl); 1235 (Ar-O-C) cm-1, 1H-NMR (CDCl3) : δ 9.86
(s,1H,-CHO) , 5.15(s,2H,-O-CH2-) 6.96-8.03(m,7H, ArH) 3.94 (s,3H,-OCH3) .Mass m/z 276 . M.F.:C15H13O3Cl
1-Aryl-3-[4’-(o-chlorobenzyloxy )-3’-methoxyphenyl]-propenones (1a-l) :
Yield 72%, m.p. 700C; IR(KBr) : ν 2951,2874,1466 (Alkane,-CH3), 1260 (-OCH3) ,640 (-C-Cl); 1235 (Ar-O-C) , 1672 (C=O) ,
1583 (C=C) ,3061,1506,1163,818 (Aromatic) ,cm-1; 1H-NMR (CDCl3) : δ 3.88, (s,6H,-OCH3) , 6.86 & 7.73 (d,2H,-CH=CH-),
5.15(s,2H,-O-CH2-) ,6.96-8.03(m,11H, ArH) , .Mass m/z 408.5 .M.F.:C24H21O4Cl .
General procedure for the preparation of 3-Aryl-5-[4’-(o-chlorobenzyloxy)-3’-methoxyphenyl]-4,-5-dihydro-1H-pyrazoles (2a-l) :
A mixture of Hydrazine hydrate (0.01M) , 1-Aryl-3-[4’-(o- chlorobenzyloxy )-3’-methoxyphenyl]-propenones (1a-l) (0.01M) and
NaOH (0.01M) in methanol was refluxed with stirring about (6-8 hrs) untiill complete the reaction which was monitored by
formation of precipitation of pyrazoline products.
3-Aryl-5-[4’-(o-chlorobenzyloxy)-3’-methoxyphenyl]-4,-5-dihydro-1H-pyrazoles (2a-l) :
Yield 67%, m.p. 140 0C; IR(KBr) : ν 2951,1458 (Alkane,-CH3), 1242 (-OCH3) ,793 (-C-Cl); 1255 (Ar-O-C) , 1608 (C=N) ,
3035,1517,1097,835 (Aromatic), 2310 (-NH-), cm-1; 1H-NMR (CDCl3) : δ 3.12, 3.68 (dd,2H,-CH2-pyr) , 5.51 (dd,1H,-CH-,pyr),
5.02 (s,2H,-O-CH2-) ,6.68-7.70 (m,12H, ArH) ,3.94 (s,6H,-OCH3) .Mass m/z 422.5 . M.F.:C24H23N2O3Cl .
Characterization data of the compounds 1a-l and 2a-l
Molecular
Mole.Wt.
Nitrogen %
The International Journal Of Science & Technoledge (ISSN 2321 – 919X) Molecular
Mole.Wt.
Nitrogen %
Antibacterial activity (zone of inhibition in mm)
Antifungal
activity
S.aureus
B.subtillis
P.vulgaris
The International Journal Of Science & Technoledge (ISSN 2321 – 919X) 6. Conclusion
The present study leads to a convenient synthetic method for the synthesis of new compounds. Which show significant
antibacterial and antifungal activity. Further investigation with appropriate structural modification of the above compounds may
result in therapeutically useful products.

7. Acknowledgment
The authors are thankful to authorities of Kamani Science College, Amreli for providing research facilities and we are also
thankful to Department of Chemistry Saurashtra University Rajkot for I.R., N.M.R., Mass spectral & elemental analysis.
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