Novel Syntheses of Some 1 , 2 , 4-Triazoles as Potent Bacteriocidal Agents

A facile syntheses of 4-aryl-5-(isomeric pyridoyl)-3H-1, 2, 4triazoles as potent bacteriocidal agents are described. The newly synthesized compounds were characterized by spectral and elemental analyses. Some compounds were screened for their antibacterial activity against S. aureus, E. coli, B. subtilis and P.aeruginosa. All compounds carrying 1, 2, 4triazole moiety showed significant biological activity.


Experimental
Melting and boiling points were determined on a Gallen Kamp apparatus in open capillaries and are uncorrected.IR spectra (KBr in cm -1 ) were recorded on a Jasco FT-IR 5300 spectrophotometer and PMR spectra (DMSO-d6) on an EM 390 spectrometer using TMS as an internal standard (chemical shift in δ ppm).Purity of the compounds was checked by TLC using silica gel G.All compounds showed satisfactory elemental analyses.

4-Methylphenyl isothiocyanate (1)
A mixture of 4-methylphenyl amine (0.01 mol), carbon disulfide (0.01 mol) and methanol (50 mL) was cooled to 15 0 C. Ammonia (0.01 mol) was added drop wise to the reaction mixture with continuous stirring.The mixture was allowed to stand overnight.Water was added to the mixture (350 mL).An aqueous solution of lead nitrate (0.01 mol) was slowly added to the solution.The mixture was then steam distilled to yield 4-methylphenyl isothiocyanate (1).The IR (KBr) of the isolated 4-methylphenyl isothiocyanate indicates a prominent characteristic band at 2071 cm -1 attributed to an N=C=S group (yield 70%).

General procedure
A mixture of compounds (2a-c) (0.01 mol) and 2 M sodium hydroxide solution (30 mL) was refluxed for the period of 40 minutes.The resulting solution was cooled and poured on crushed ice.The solid separated was filtered, washed with water and recrystallized from ethanol-water to give compounds (3a-c) yield (75-85%

Antibacterial activity
The antibacterial activity of three compounds was studied by employing filter paper disc method [9][10][11][12] .Representative organisms selected for evaluation of antibacterial activity were S. aureus, E.coli, B.subtilis and P.aeruginosa.The antibacterial activity of each compound was evaluated at 100 µg mL -1 and 10 µg mL -1 concentrations.The compounds were tested as a solution or suspension in DMF.An important and useful drug ampicillin was also tested under similar conditions, with view to compare the results.Ampicillin is a beta-lactam antibiotic 13 that has been used extensively to treat bacterial infections since 1961.Ampicillin is designated chemically as (2S, 5R, 6R)-6-([(2R)-2amino-2-phenylacetyl] amino)-3, 3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane-2carboxylicacid. Ampicillin is able to penetrate gram-positive and some gram-negative bacteria 14 .Ampicillin acts as a competitive inhibitor of enzyme transpeptidase.The results indicate that all three compounds showed good activity.(Table 1) All three compounds showed very good activity against S. aureus, E.coli, B.subtilis and P.aeruginosa.From the above observation it is clear that the 1, 2, 4-triazole derivatives are more active and play a prominent role in the biological activity.

Results and Discussion
In

Conclusion
In conclusion, a group of 1, 2, 4-triazole derivatives were synthesized and characterized.All these compounds containing 1, 2, 4-triazole moiety is more active and plays a prominent role in biological activity.The structure of all the compounds are confirmed by IR, PMR & MS spectral data and are further supported by correct elemental analysis.

Table 1 .
Evaluation of antibacterial activity of the compounds.