Experiment 20
Pre-Lab Review
Reactions of Aldehydes and Ketones
1. Are any specific safety alerts given in the experiment? List any that are given.
2. Are any specific disposal directions given in the experiment? List any that are given.
3. What types of aldehydes and ketones would you expect to be water-soluble?
4. What results are expected when the DNP test is done on:
| a. an aldehyde? | |
| b. a Ketone? |
5. What size test tubes are used in Part B?
6. What results are expected when a Tollens' test is done on:
| a. an aldehyde? | |
| b. a ketone? |
7. What type of aldehyde reacts quite readily with chromic acid?
8. What structural features give positive results in the iodoform test?
Data and Report Sheet
Reactions of Aldehydes and Ketones
A. DNP Test for aldehydes and Ketones
Table 20.1(data)
| Sample | Tube No. | Result of Adding DNP | |
| Acetone | 1 | ||
| Butyraldehyde | 2 | ||
| Flavoring agent | 3 | ||
| Unknown | 4 | ||
B. Tollens' Reagent
Table 20.2 (data)
| Sample | Tube no. | Observations | |
| Acetone | 1 | ||
| Butyraldehyde | 2 | ||
| Flavoring agent | 3 | ||
| Unknown | 4 | ||
C. Chromic Acid Test for Aldehydes
Table 20.3 (data)
| Sample | Tube No. | Color After 10 Seconds |
Color After 12 Minutes |
| Acetone | 1 | ||
| Butyraldehyde | 2 | ||
| p-Tolualdehyde | 3 | ||
| Flavoring agent | 4 | ||
| Unknown | 5 |
D. Iodoform Test
Table 20.4 (data)
| Sample | Tube No. | Observations | |
| Acetone | 1 | ||
| Butyraldehyde | 2 | ||
| 2-Butanone | 3 | ||
| Flavoring agent | 4 | ||
| Unknown | 5 | ||
Characterization of Unknowns
Table 20.5 (report)
| Unknown ID Number | ||||
| Test | Test Result for Unknown |
Conclusion for Unknown |
Test Result for Flavoring Agent |
Conclusion for Flavoring Agent |
| DNP | ||||
| Tollens' | ||||
| Chromic Acid | ||||
| Iodoform |
I. Circle the letter that best describes your unknown.
a. Aliphatic aldehyde
b. Aromatic aldehyde
c. Ketone
II. Which of the above possibilities best describes the flavoring agent?
III. Check below if a
group is present
in
a. your unknown?
b. the flavoring agent?
Questions
1. Which of the following reagents or tests would you use
to differentiate between
and
a. Iodoform
b. Chromic Acid
c. Tollens'
d. DNP
Explain your answer:
2. Which of the following reagents or tests would you use
to differentiate between
and
a. Iodoform
b. Chromic Acid
c. Tollens'
d. DNP
Explain your answer:
3. An unknown compound is tested with several reagents,
yielding the following results:
DNP test: A thick, yellow precipitate formed.
Tollens' test: No precipitate or mirror was detected.
Iodoform test: A yellow precipitate formed.
Which of the following formulas could best represent the compound?
a.
b.
c.
d.
Explain your answer:
Submit your work for grading: (Submit button removed for sample)