Dr. B. R. Ambedkar University
Question
Asked 12th Apr, 2017
What kind of catalyst I should use to synthesize N-acetyl, N-phenyl, and N-benzoylpyrazoline from chalcone?
I already used CH3COOH but there still chalcone in my product that I cannot separated from pyrazoline. I tried column chromatography and also preparative tlc but still more than one spot in my product. It also contained 4 spots before purification. The one spot was chalcone, green colored under uv 366 nm, the other was pyrazoline that blue colored under uv 366 nm but not very strong fluorescence, and 2 others I don't know and it was not my starting materials I used and do not fluorescence under uv 366 nm. I used vanillin and 4-chloroacetophenone to synthesize chalcone.
Most recent answer
re-crystallization using ethanol is correct. just you soluble the compound in ethanol then evaporate the 50% ethanol then allow to stand for few hours. crystals will be separated.
All Answers (6)
Alexandria University
Nariswari
You wrote: What kind of catalyst I should use to synthesize N-acetyl, N-phenyl, and N-benzoylpyrazoline from chalcone?
These compounds have been synthesized and the best way is to go and read
For N-acetyl, see
Sharma, Manmohan et al, Medicinal Chemistry Research, 23(10), 4337-4344; 2014
*General/Typical Procedure: Procedure for the synthesis of 3,5 diaryl N-Acetyl pyrazoline (DNAP). A mixture of diarylpropenone (1 mmol) in acetic acid and hydrazine hydrate (1 mmol) was refluxed for 2 h. The mixture was then poured onto crushed ice to get crude pyrazole, which was purified by crystallization from methanol to afford the desired product. 3,5 Diaryl N-Acetyl pyrazoline (DNAP)
For N-phenyl, see
--- Tengli, Anand Kumar et al, Indian Journal of Heterocyclic Chemistry, 16(4), 333-336; 2007
General/Typical Procedure: reacting equiv molar amount of diarylpropenone and phenylhydrazine in ethanol and heat using conventional source or microwave.
For N-benzoyl, see
--- Jain, Shraddha and Chourasia, O. P., Journal of the Institution of Chemists (India), 82(2), 37-40; 2010
General/Typical Procedure: This is two step reaction
1st: reacting equiv molar amount of diarylpropenone and hydrazine in ethanol and heat
2nd: N-benzoylation of the resulting product from the first step using benzoyl chloride in pyridine.
Good luck
Alexandria University
Try reflux in acetic acid with few drops of acetic anhydride, then pour on crushed ice.
Universitas Gadjah Mada
Can I ask what is the meaning of recrystallize from ethanol? is it recrystallization using ethanol or recrystallize to remove ethanol?
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