I.
Techniques in Organic Lab and TLC Analysis
1. Write a short description of each technique below. Be sure to include the purpose,
a description of any apparatus used, and any other pertinent information.
a. Thin-Layer Chromatography
2. A TLC plate displays the compound spot approximately 3.2 cm above the base line
upon visualization; the solvent ran 4.1 cm up the plate. Calculate the Rf value of the
compound.
3. Two unknown samples are found to have the same Rf value under identical TLC
conditions. Are they the same compound? Explain.
4. A TLC plate has a polar stationary phase (silica gel) and a non-polar mobile phase
(EtOAc/Hexanes). Two unknown compounds are spotted and allowed to run up the
plate. The spot for Compound A traveled 1.3 cm above the base line; Compound B
traveled 3.6 cm above the base line. Which compound would you expect to be more
polar? Why?
5. Identify at least 3 different methods used for visualization of a TLC plate.
II.
Experiment 1: Extraction of Caffeine from Tea
1. Write a short description of each technique below. Be sure to include the purpose,
a description of any apparatus used, and any other pertinent information.
a. Vacuum Filtration
b. Using Pasteur Pipets
c. Microscale Extraction
d. Drying Agents
e. Solvent Removal
2. Write the structure of caffeine:
3. What is the purpose of adding CaCO3 to the reaction vessel?
4. When performing an extraction with dichloromethane as the organic solvent,
would you expect the aqueous layer to be on top or on bottom? Why?
5. What is the function of anhydrous MgSO4 in this experiment?
III.
Experiment 9.1: SN1/SN2 Reactivity of Alkyl Halides
1. List the experimental conditions that favor SN1 reactions and those that favor SN2
reactions.
2. Write the reactions performed in this experiment:
a. SN1 Favored:
b. SN2 Favored:
3. Describe the mechanism for SN2 reactions; include a description of the transition
state and the resulting stereochemistry of the product.
4. Describe the mechanism for SN1 reactions; identify the key differences between
this mechanism, and the mechanism described in Question 3.
5. Which one of the following alkyl halides gives a stable carbocation?
6. Rank the alkyl halides above in terms of increasing SN1 reactivity.
IV.
Experiment 9.2: Synthesis and Identification of Alkyl Bromides from Unknown
Alcohols
1. Write a short description of each technique below. Be sure to include the purpose,
a description of any apparatus used, and any other pertinent information.
a. Reflux
b. Simple Distillation
c. Microscale Extractions
d. Short-Path Distillation
e. NMR Spectroscopy
2. Write the mechanism of the reaction performed in this experiment.
3. What is the purpose of sulfuric acid in the reaction?
4. What is the function of the anhydrous CaCl2?
5. In the extraction steps, why was the product washed with aqueous sodium
bicarbonate?
6. Review the 1H NMR spectra provided by your teaching assistant. Be sure to
practice identifying unknown compounds when given the 1H NMR spectra and
molecular formula.
7. Assuming 80% yield, how many grams of the alcohol starting material do you
need to prepare 2.0 moles of the desired bromide product?
V.
Experiment 4: Synthesis of Salicylic Acid
1. Write a short description of each technique below. Be sure to include the purpose,
a description of any apparatus used, and any other pertinent information.
a. Microscale Reflux
b. Boiling Stones
c. Heating Methods
d. Microscale Recrystallization
e. Melting Points
2. Write the reaction performed in this experiment.
3. Write the mechanism for the reaction above.
4. What is hydrolysis?
5. What is the catalyst of the reaction?
6. Suppose that you obtain 1.0 g of salicylic acid (MW = 138) from the hydrolysis of
1.3 mL of methyl salicylate (MW= 152, density = 1.17 g/mL). Calculate the
percent yield.
VI.
Experiment 5: Analgesics and Synthesis of Aspirin
1. Write a short description of each technique below. Be sure to include the purpose,
a description of any apparatus used, and any other pertinent information.
a. Heating Methods
b. Microscale Recrystallization
c. Mixed Solvent for Recrystallization
d. Melting Points
2. Write the reaction performed in this experiment.
3. Write the mechanism for the reaction above.
4. What is the function of the concentrated phosphoric acid in this reaction?
5. The process by which aspirin is synthesized from salicylic acid is best described as
____________________________.
VII.
Project 4: Interconversion of 4-tert-Butylcyclohexanol and 4-tertButylcyclohexanone
1. Write a short description of each technique below. Be sure to include the purpose,
a description of any apparatus used, and any other pertinent information.
a. IR Spectroscopy
2. Write the reaction for the oxidation performed in this experiment. Identify the
oxidizing agent.
3. Write the reaction for the reduction performed in this experiment. Identify the
reducing agent.
4. Predict the products for the reaction shown on the following page. Draw in the
mechanism arrows.
5. In covalent organic systems, it is easiest to think of oxidation as the
_______________________________________________________________.
6.The oxidation of a primary alcohol yields a(n) ________________________.
7. The oxidation of a secondary alcohol yields a(n) _______________________.
8. The oxidation of a tertiary alcohol ___________________________________.
9. Draw the cis-isomer of 4-tert-butylcyclohexanol. What is the approximate 1H
NMR shift of the methine proton on the carbon bearing the hydroxyl group?
10. Draw the trans-isomer of 4-tert-butylcyclohexanol. What is the approximate 1H
NMR shift of the methine proton on the carbon bearing the hydroxyl group?
11. What equation would you use to determine the ratio of cis-to-trans isomers based
on the 1H NMR integration?
12. What equation would you use to determine the % of cis-isomers present based on
the 1H NMR integration?