Medicinal chemistry - Paperback

by Sunitha N (Author), Appa Rao B (Author)

SYNTHESIS AND CHARACTERIZATION OF 3,5- DIMETHYL PYRAZOLEAIM: To synthesize 3,5- dimethyl pyrazole in the laboratory and characterize the crude and re-crystallized product.APPARATUS/INSTRUMENT REQUIRED: Reflux condenser, round bottomed flask, beaker, glass rod, pipette, buchner funnel, filtering flask, water bath, watch glass, capillary tube, thiele's tube, thermometer, electronic balance, vacuum pump and filter paper.CHEMICALS REQUIRED: Acetyl acetone, hydrazine hydrate, ethyl alcohol and n-hexane/petroleum ether.CHEMICAL REACTION: REACTION MECHANISM: PRINCIPLE: Substituted pyrazoles are prepared by condensation of 1,3-diketones with hydrazine. For example, acetyl acetone and hydrazine gives 3,5-dimethyl pyrazole. The enamine and imine formed undergo cyclization to yield the product.PROCEDURE: 1. Take 0.06 moles of hydrazine hydrate in a 250 ml flask.2. To this, add 25 mL of ethyl alcohol with constant stirring.3. Now place the flask in an ice-old water or ice-bath and wait for 10 minutes.