(1) Place 30g of finely ground black pepper in a porous thimble 
in the central chamber of a soxhlet extractor and 175ml of 95% 
ethanol in a RB flask. Gently heat solvent under reflux for
6 hours. Concentrate the solution to a volume of 20-30ml on a 
rotary evaporator and add 30ml of warm 2M ethanolic potassium 
hydroxide (this is ESSENTIAL to keep all the acidic components in 
solution). After shaking the warm mixture well, filter the solution 
and remove any insoluble materials (quite a bit). While keeping the 
solution warm over a water bath, and water until no more yellow 
solid forms. Allow the resulting solution to stand overnight and 
then isolate yellow precipitate that has formed by filtration. 
Recrystalise the crude product in hot 3:2 acteone/hexane, cooling 
in ice bath if necessary to promote recyrstallisation. The resulting 
product (Piperine) is in the form of spectacular yellow needles, a 
yield of around 2g (in my case) was obtained.

(2) Hydrolysis of Piperine to Piperic Acid: (These intructions are 
in the small scale, obviously they can be increased) Heat mixture of 
0.1g piperine and 10ml of 2M ethanolic potassium hydroxide under 
reflux for 1.5h. Evaporate the ethanolic solution to dryness under 
vacuum. Suspen the solid potassium piperate that remains in the flask 
in about 5ml of hot water and carefully acidify the suspension with 
6M HCL. Collect the precipitate, wash with cold water, recyrystalise 
from COLD ethanol. The mp of the product should be around 206C (a 
little less than the literature values due to the slight Chavacine 
impurification (Chavacine is the Z,Z isomer of piperic acid (E,E))


[http://www.rhodium.ws/chemistry/piperine.txt]


