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	Chromic Acid Test Results
1-butanol
2-butanol
2-methyl-2-butanol
diphenylmethanol
product

LUCAS TEST:

R₃COH + HCl + Zn(Cl)₂ ---> R₃CCl + H₂O

1. To each of 3 test tubes, add 4 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 40 drops 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.

Stir the contents of the test tubes into 800 mL of water that you have added to your 1L

beaker, and subsequently dump the beakers contents down the sink.

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

Exercise:

Write the equation for a positive test for each of the tests performed. Tell what you

observed that constituted a positive test.