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Chapter – 4 Studies on different types of reactions…..
mobile phase. After the reaction to be completed, the reaction mixture was
cooled to room temperature and the product was separated by filtration. The
product was washed with methanol and dried to give desired product in good
yield which was recrystallized by DMF. (Physical data of the synthesized end
products are summarized in the table 4.10.3)
METHOD – (B) MICROWAVE APPROACH
0.01 mole of 4-hydroxycoumarin was dissolved into 20 ml of
dimethylformamide into 100 ml microwave flask. 0.01 mole of an appropriately
substituted pyrazole-4-carboxaldehyde was added to the above flask along
with few drops of piperidine. The reaction mixture was irradiated under
microwave irradiation using Qpro-M microwave synthesizer for the desired
time at 400 W. The progress and the completion of the reaction were checked
at interval of every one min. by silica gel-G F254 thin layer chromatography
using hexane : ethyl acetate (6 : 4) as a mobile phase. After the reaction to be
completed, the reaction mixture was scratched into 30 ml of methanol. The
separated product was filtered off and washed with methanol and it was dried
to give desired product in good yield which was recrystallized by DMF.
(Physical data of the synthesized end products are summarized in the table
4.10.3)
Comparative results of method (A) and method (B) are summarized as under.
Code No.
Reaction Condition % Yield
Method (A) Method (B)
Temp.
(°C)
Time
(hrs.)
Watt
(W)
Temp.
(°C)
Time
(min.)
Method
(A)
Method
(B)
DNJ-901 90-95 4.5 400 110 3.0 68 85
DNJ-902 90-95 5.0 400 110 3.3 64 80
DNJ-903 90-95 4.8 400 110 3.1 70 83
DNJ-904 90-95 5.5 400 110 3.2 72 81
DNJ-905 90-95 5.3 400 110 3.0 66 79
Department of Chemistry, Saurashtra University, Rajkot – 360 005 228