Aldol Lab

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  • Topic: Aldehyde, Solvent, Ethanol
  • Pages : 2 (498 words )
  • Download(s) : 48
  • Published : September 17, 2008
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1)With 1-mL graduated pipet, measure 0.40 mL of the unknown labled “no.XX-.40 mL 2) With another 1ml graduated pipet measure 0.10 Ml of the unknown labled “no. XX-0.10 mL” 3) Add the compounds to the same Erlenmeyer flask

4) Add 2.0 mL of 95% ethanol and 1.5 mL of 2 M sodium hydroxide solution to the flask 5)Stir with magnetic stirrer for 15 minutes or longer if precipitate still forming (if cloudy after 15 mina heat mixture on a asteam bath or in boiling water for 10 mins then cool to room temp) When precipitate is complete cool flask in ice-water bath for 10 mins MEANWHILE--- A)place 4 mL of 4 acetic acid in 95% ethanl in a test tube

B)Repeat this procedure with 2mL of 4% acetic acid in 95 % ethanol (v/v) Chill the test tubes containing these solutions in the ice water bath.

Collect the product by vacuum filtration
Disconnect vacuum and rinse product with 2 Ml of ice cold ethanol Reconnect vacuum and draw the liquid from the product
Repeat washing procedure with 2 Ml of acetic acid/ethanol solution Finally wash the crude product with the remaining 2 mL of ethanol

Test 95% ethanol and toluene
Addition of a few drops hexane may be necessary to promote crystallization If not satisfactory test 9:1 v/v mixture of 95% ethanol/acetone


Characterization of aldol product
Perform this test on both unknown compounds
Add 1 drop of the unknown compound to a test tube and add 1 mL of acetone Then Add 1 drop of the chromic acid-sulfuric test reagent directly into the solution. Shake the mixture
A green bluish green precipitate appears within 1 min if the unknown compound is an aldehyde (Aliphatic aldehydes give precipitates with 15 s whereas aromatic aldehydes usually take 30-60s. Acetone and other keytones oxidize in this solution only after 2-3 mins.

Place 2 drops of the unknown aldehyde and 0.5mL of ethanol in a 10 X 75 nm test tube Add water dropwise, shaking after each drop until the cloudiness...
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