CHE XXXXXXXXXXManual 3E.pdf
Copyright © 2014 Pearson Education, Inc. 273
Pre-Lab Study Questions 24
1. Draw the condensed structural formula, if any, of the product from each of the following:
a.
.
c.
d.
2. Draw the condensed structural formula of each of the following:
a. 2-methylbutanal b. 3-pentanone
c. 3-
omopropanal d. 2-methylcyclopentanone
Date Name
Section Team
Instructor
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REPORT SHEET
Aldehydes and Ketones
LAB
24
A. Structures of Some Aldehydes and Ketones
Formaldehyde
Acetaldehyde
IUPAC Name __________________________ IUPAC Name _______________________
Propionaldehyde Acetone
IUPAC Name ___________________________ IUPAC Name _______________________
Butanone Cyclohexanone
Common Name __________________________
B. Properties of Aldehydes and Ketones
1. Odor 2. Condensed
Structural Formula
3. Aldehyde or
Ketone?
Acetone
Benzaldehyde
Camphor
Vanillin
Cinnamaldehyde
Date Name
Section Team
Instructor
276 Laboratory Manual for General, Organic, and Biological Chemistry
C. Solubility, Iodoform
1. Soluble? 2. Iodoform
Test
3. Methyl
Ketone?
4. Color 5. Oxidation?
(yes/no)
Propanol
Benzaldehyde
Acetone
Cyclohexanone
Unknown
6. Identify the unknown as propanal, benzaldehyde, acetone, or cyclohexanone.
Give your reasoning.
Questions and Problems
Q1 Indicate the test results for each of the following compounds in the iodoform test
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Propanal
Aldehydes and Ketones 277
Q2 Two compounds, A and B, have the formula of 3 6C H O. Determine their con-
densed structural formulas and names using the following test results.
a. Compound A forms a red-orange precipita
not react with iodoform.
b. Compound B forms a yellow solid in the iodoform test but does not react with
Q3 What chemical tests could you use to distinguish between 2-pentanone and
3-pentanone?
Q4 What aldehyde or ketone might be present in the following everyday products?
Almond-flavored cookies _______________________
Candies with cinnamon flavor _______________________
Nail polish remover _______________________
CHE XXXXXXXXXXManual 3E.pdf
Copyright © 2014 Pearson Education, Inc. 269
LABORATORY GOALS
LAB INFORMATION
Time: 2 h
Comments: Flammable compounds are used in this experiment. Do not use burners.
In tests with color changes, carefully observe the color of the reactants before
they are mixed.
Tear out the lab report sheets and place them beside the matching procedures.
Related Topics: Aldehydes, ketones, oxidation of aldehydes
Dispose of all chemicals as directed by your lab instructor.
CHEMICAL CONCEPTS
A. Structures of Some Aldehydes and Ketones
Aldehydes and ketones both contain the ca
onyl group. In an aldehyde, the ca
onyl group has a hydrogen
atom attached; the aldehyde functional group occurs at the end of the ca
on chain. In a ketone, the ca
onyl
group is located between two of the ca
on atoms within the chain.
B. Properties of Aldehydes and Ketones
Many aldehydes and ketones have sharp odors. If you have taken a biology class, you may have noticed
odors. Benzaldehyde, the simplest aromatic aldehyde, has an aroma of almonds. Vanillin, an aromatic
aldehyde, is found in the seed pods of the vanilla plant. When you use fingernail polish remover, you
may notice the strong odor of acetone, the simplest ketone, which is used as the solvent.
Aldehydes and Ketones 24
270 Laboratory Manual for General, Organic, and Biological Chemistry
The vanilla bean is the dried fruit of the vanilla plants. Vanilla extract is prepared by soaking vanilla beans in
ethanol and water.
Acetone (propanone) is used as a solvent for paint and nail polish.
Ketones containing a methyl group attached to the ca
onyl give a reaction with iodine 2(I ) in a solution
of NaOH. The reaction produces solid, yellow iodoform, 3CHI . Iodoform, which has a strong medicinal
odor, is used as an antiseptic.
Oxidation of Aldehydes and Ketones
2Cu . Because ketones
cannot oxidize, this test can distinguish aldehydes from ketones. In the oxidation reaction, the blue-
green 2Cu is reduced to cuprous ion (Cu ), which forms a reddish-orange precipitate of 2Cu O.
Identification of an Unknown
Using the results of the tests, an unknown substance can be identified as an aldehyde or a ketone.
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Aldehydes and Ketones 271
EXPERIMENTAL PROCEDURES GOGGLES REQUIRED!
A. Structures of Some Aldehydes and Ketones
Materials: Display of models: formaldehyde, acetaldehyde, propionaldehyde, acetone, butanone, and
cyclohexanone
1. Observe models of formaldehyde, acetaldehyde, propionaldehyde, acetone, butanone, and cyclo-
hexanone. Draw each of their condensed structural formulas.
2. Write the IUPAC or common names (if any) for each.
B. Properties of Aldehydes and Ketones
Materials: Test tubes, droppers, 5- or 10-mL graduated cylinder, acetone, benzaldehyde, camphor, vanillin,
cinnamaldehyde, propionaldehyde, and cyclohexanone, chemistry handbook or Internet access
1. Carefully detect the odor of samples of acetone, benzaldehyde, camphor, vanillin, and cinnamal-
dehyde. Your instructor will demonstrate how to fan the fumes above the test tube sample. Record
your observations.
2. Draw each of the condensed structural formulas. You may need a chemistry handbook or the
Internet.
3. Identify each as a ketone or aldehyde.
C. Solubility, Iodoform
Solubility in Water
Materials: Test tubes (5), dropper, 5 or 10 mL graduated cylinder 10% NaOH, propanal, benzaldehyde,
acetone, cyclohexanone, and an unknown
1. Place 2 mL of water in each of five test tubes. Add 5 drops propanal, benzaldehyde, acetone,
cyclohexanone, and an unknown, to separate test tubes. Mix. If two separate layers form or the
mixture turns cloudy, the aldehyde or ketone is not soluble. Save test tubes for Part C.2.
Iodoform Test for Methyl Ketones
Materials: Test tubes from Part C.1, dropper, 10% NaOH, warm water bath, and iodine test reagent
2. Using the test tube samples from Part C.1, add 10 drops of 10% NaOH to each. Warm the tubes
tion of a yellow solid. Record your observations.
3. State if a methyl ketone is present or not.
Materials: Test tubes, propionaldehyde (propanal), benzaldehyde, acetone, cyclohexanone, unknoene-
s, boiling water bath
4. Place 10 drops of propionaldehyde (propanal), benzaldehyde, acetone, cyclohexanone, and unknown
in separate test tubes. Label. Add 2 mL of Benedi
tubes in a boiling water bath for 5 min. After 5 min, record the color of the samples. The appearance
of the red-orange color of 2Cu O indicates that oxidation has occu
ed. Moderate amounts of 2Cu O
will blend with the blue 2Cu solution to form green or rust color.
5. Identify the compounds that were oxidized.
6. If you were given an unknown compound, you can now compare the results of the tests for
the unknown with the tests you performed with known aldehydes and ketones. Identify your
unknown.