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Chapter – 4 Studies on different types of reactions…..
4.9 EXPERIMENTAL
4.9.1 PREPARATION OF PYRAZOLE ALDEHYDE
STEP – 1 PREPARATION OF ACETOPHENONE PHENYL HYDRAZONE
0.1 mole of appropriately substituted acetophenone was dissolved in
50 ml of ethanol into 250 ml round bottom flask. 0.1 mole of Phenyl hydrazine
was added to above flask along with 3-4 drops of glacial acetic acid. The
reaction mixture was refluxed for 5-6 hours. The progress and the completion
of the reaction were checked by silica gel-G F254 thin layer chromatography
using toluene : ethyl acetate (7 : 3) as a mobile phase. After the reaction to be
completed, the reaction mixture was cooled to room temperature and the
crystalline product was separated by filtration. The product was washed with
ethanol and dried to give substituted acetone phenyl hydrazone in good yield
which was pure enough to use as such for the next step.
Code No. MF MW (g/m) MP (°C) % Yield
APH-01 C14H13N3O2 255 106-108 85
APH-02 C14H13N3O2 255 134-136 80
APH-03 C14H14N2 210 126-128 78
APH-04 C14H13ClN2 244 ----- 79
APH-05 C14H13FN2 228 ----- 72
STEP – 2 PREPARATION OF PYRAZOLE ALDEHYDE
25 ml of dry dimethylformamide was transferred into 250 ml flat bottom
flask. 3 ml of phosphorous oxychloride was added drop wise to above flask
under stirring at 0-5°C. After completion of the addition, the mixture was
stirred at this temperature for 10-15 min. 0.03 mole of freshly prepared
acetophenone phenyl hydrazone was added to above mixture and the content
was heated on water bath for 5-6 hours. The progress and the completion of
the reaction were checked by silica gel-G F254 thin layer chromatography
using toluene : ethyl acetate (7 : 3) as a mobile phase. After the reaction to be
completed, the reaction mixture was cooled to room temperature and the
Department of Chemistry, Saurashtra University, Rajkot – 360 005 224