Principle: 1,3-substituted pyrazole is prepared by cyclization of diarylhydrazone and vicinaldiol in presence of ferric chloride and tert-butylhydroperoxide (TBHP) which is also called regio selective synthesis of substituted pyrazole.
Aim: To prepare 1,3-diphenyl pyrazole from diphenyl hydrazone and a vicinal diol.
Use: Can be used as an antibacterial and antiviral agent.
Buchner funnel, etc
About 4.55 g of 1-benzyledene-2-phenyl hydrazine is dissolved in the solution of 25 ml of vicinal diol and ferric chloride (5 mol %). Then another solution of tert-butyl hydroperoxide (5.3 g) in 25 ml of acetyl-acetone is added to it. Mix solution is maintained at a temperature range of 90 to 100o C.
The mixed solution is left to reach room temperature and stirred for 6 hours. Content is poured into water and extracted with ethyl-acetate three times. The combined organic solution is washed with water, then with a saturated solution of sodium chloride, passed through sodium sulphate, and evaporated under a vacuum. About 3.15 g of the final product is found with m.p: 185oC.
Calculation of yield:
– Molecular Formula (MF) of 1-benzyledene-2-phenyl hydrazine = C13H12N2
– MF of 1,3-diphenyl pyrazole = C15H12N2
– Molecular weight (MW) of 1-benzyledene-2-phenyl hydrazine = 196 g/ mol
– MW of 1,3-diphenyl pyrazole = 220 g/ mol
196 g of 1-benzyledene-2-phenyl hydrazine yields 1,3-diphenyl pyrazole = 220 g
4.55 g of 1-benzyledene-2-phenyl hydrazine shall yield 1,3-diphenyl pyrazole = (220 / 196) × 4.55 = 5.1 g
Therefore, Theoretical yield of 1,3-diphenyl pyrazole = 5.1 g
If reported Practical yield = 3.15 g
Then, Percentage Practical yield = (Practical yield / Theoretical yield) × 100
= (3.15 / 5.1) × 100 = 61.76 %
The percent yield of 1,3-diphenyl pyrazole is 61.75 % with m.p. 185 °C.
- N. Panda, A. K. Jena, J. Org. Chem., 2012, 77, 9401-9406.
- Practical Heterocyclic Chemistry by A. O. Fitton and R. K. Smalley Academic Press London and New York, Page. 25.
- Test for purity of water
- Swelling power of bentonite
- Limit test for iron
- Limit test for lead
- Determination of saponification value of the given oil/fat
- Determination of saponification value of fat (coconut oil)
🔴 Would you like to attempt Labmonk Daily quiz? Click here
🔵 Check out Jobs & Exam Notices. Labmonk Notice Board
🔴 Labmonk Scholarships. Click here
🔵 Labmonk Blog. Click here
🔴 Do you need notes? Click here
Watch Career related videos on Youtube: Watch now !!