Isolation of caffeine
latkan

Dundee, UK

#1 Oct 7, 2006
Need help with these 2 questions:( isolation of caffeine from tea)
In this exp caffeine is isolated from tea by extraction into water followed by extraction into dichloromethane, evaporation and sublimation.
1) why is lead acetate added to tea?
2) why is caffeine extracted 3 times with 20 ml of chloroform rather than once with 60 ml?
Any help would be great guys.
Kieran

Dublin, Ireland

#2 Feb 10, 2007
latkan wrote:
Need help with these 2 questions:( isolation of caffeine from tea)
In this exp caffeine is isolated from tea by extraction into water followed by extraction into dichloromethane, evaporation and sublimation.
1) why is lead acetate added to tea?
2) why is caffeine extracted 3 times with 20 ml of chloroform rather than once with 60 ml?
Any help would be great guys.
I'll offer an answer for question 2. As with many things in science it is often better to try and dissolve a chemical in the smallest amount of liquid. The reasoning is that you get a concentrated stock solution allowing you to take small aliquotes to make a series of dilute solutions in an experiment. To carry out three extractions with 20 mls each will ensure that you can extract the greatest amount with each successive step. To just simply add 60 mls most certainly wont give you the same (high) concentration as the 20ml steps would in the same space of time.
Jeff

Seattle, WA

#3 Mar 15, 2007
1. Acetate is added to solubize and liberate the caffeine for extraction. You cant work with massive leaves. The lead (Pb) ion can be used to precipitate out undesired impurities.
shrikant

Bangalore, India

#4 Jul 26, 2007
very good, please give such type of answers regarding use of chemicals while performing any type of extraction regarding herbal drugs. thank u
MARTINA

Virginia Beach, VA

#5 Sep 2, 2007
WHY IS IT NECESSARY TO COOL THE FILTRATE (AFTER USING VACUUM FILTRATION) BEFORE ADDING METHYLENE CHLORIDE?
KARTHIK

Guildford, UK

#6 Oct 5, 2007
WHEN ACCETATE IS ADDED TO THE TEA TO BIND AND RETAIN CERTAIN TYPES OF OTHER COMPONETS. SUGGEEST WHAT THESE MIGHT BE? PLEASE HELP
latkan

Wembley, UK

#7 Oct 7, 2007
lol karthik I bet u go to uni of surrey :P
Rob

Darwen, UK

#8 Oct 14, 2007
haha yep def Surrey uni
ashley

Linwood, NJ

#9 Mar 24, 2008
why did the color change when sodium hydroxide was added to dichloromethane
jen

Pagadian City, Philippines

#10 Nov 11, 2008
what is the role of sodium sulfate in the isolation of caffeine?
satish kumar

Amsterdam, Netherlands

#11 Feb 24, 2009
Hai, i found good blog while i am on surfing. If u want more plz visit the blog.
http://www.biochemden.blogspot.com

thank u
shanu luhadia

Bikaner, India

#12 Mar 19, 2010
why we add lead acetate in isolation procedure of caffeine from tea leaves
Anonymous

Baghdad, Iraq

#14 May 13, 2016
Hello,please help me!
Caffeine is soluble in both chloroform and hot water,but we used water and not chloroform in it's extraction

Tell me when this thread is updated:

Subscribe Now Add to my Tracker

Add your comments below

Characters left: 4000

Please note by submitting this form you acknowledge that you have read the Terms of Service and the comment you are posting is in compliance with such terms. Be polite. Inappropriate posts may be removed by the moderator. Send us your feedback.

Biochemistry Discussions

Title Updated Last By Comments
News University of Maryland researcher's published a... (Feb '17) Feb '17 noobieR 1
News Poop, there it is: New test for exotic civet co... (Sep '13) Feb '17 Fancy Phart 4
News Dr. Hays Young, Dna Analyst and Technical Leade... (Feb '17) Feb '17 Wildbird 1
Will this have ruined my health? (Feb '17) Feb '17 Njhuckman 1
News Association of rare missense variants in the se... (Dec '16) Dec '16 Stephany McDowell 1
News Researchers uncover a new mechanistic understan... (Oct '16) Oct '16 Stephany McDowell 1
News Why the Air Force Wants to See Pilots' Sweat (Sep '16) Sep '16 Stephany McDowell 3
More from around the web