Alcohol Classification Tests
Perform these tests in pairs.
Perform the following tests on the known primary, secondary and tertiary alcohols and the diphenylmethanol
provided, and your product . (If you have no product, a bottle is provided at the front of the room - along with the
known alcohols.)
Primary and secondary alcohols give a positive test within 5 seconds.
CHROMIC ACID IN ACETONE TEST - Cr+3 is blue and indicates a positive reaction .
Primary alcohols.
3RCH2OH + 4H2CrO4 + 12H+ ----> 3RCOOH + 4Cr+3 + 13H2O
Aldehydes
3RCHO + 2H2CrO4 + 6H+ ----> 3RCOOH + 2Cr+3 + 5H2O
Secondary alcohols
3R2CHOH + 2H2CrO4 + 6H+ ----> 3R2C=O + 2Cr+3 + 8H2O
Tertiary alcohols & ketones do NOT react.
1.
Dissolve two drops or a little powder sample of the alcohol to be tested in 20 drops of acetone.
2.
Add 1 drop of chromic acid reagent and shake the tube to mix the contents. A positive reaction is indicated
by the disappearance of orange color and formation of a green or blue-green precipitate.
Color changes occurring AFTER one minute should not be construed as a positive test. (Why?).
Dispose of test tube contents into the flask in the chromic acid hood.
Compound
1-butanol
2-butanol
2-methyl-2-butanol
diphenylmethanol
product 1
product 2
Chromic Acid Test Results
LUCAS TEST:
R3COH + HCl + Zn(Cl)2 ---> R3CCl + H2O
1.
To each of 3 test tubes, add 20 drops of the primary, secondary, and tertiary known alcohols. To a fourth test
tube, add a tiny amount of diphenylmethanol. To a fifth and sixth test tube, add a tiny amount of your
products from the carbonyl reduction experiment.
2.
Add 5 mL of Lucas reagent to each tube. Stopper the tubes and shake.
3.
Allow the tubes to stand at room temperature, noting the time required for the formation of an alkyl chloride,
which will appear as an emulsion.
Dispose of test tube contents into the flask located in the lucas test hood.
Return any remaining product to the recovery bottle at the front of the lab.
Dispose of the filter paper into the recovered solids jar at the front of the lab.
Laboratory Report. Write the names of the compounds used in each test and write the observations for each
component.
Compound
Lucas Test Results
1-butanol
2-butanol
2-methyl-2-butanol
diphenylmethanol
product 1
product 2
EXERCISES
Write the equation for a positive test for each of the tests performed. Tell what you
observed that constituted a positive test.