unit 6 lab pt 2

Nitration of Methyl Benzoate
• Electrophilic aromatic substitution is electrophilic because of the high
density in the benzene ring, which is one of the components in the
experiment.
• Benzene ring is one of the most important natural products and other
useful products.
• Nitration is an important example of electrophilic substation. In this
experiment, the electrophile in nitration is the nitronium ion which is
coming from the nitric acid by pronation and loss of water, using
sulfuric acid as the dehydrating agent.
Overall Reaction
• In this experiment, methyl benzoate will be reacted with nitric acid using
sulfuric acid as the catalyst.
• The nitration of a benzene ring is an electrophilic aromatic substitution
reaction,
• Step 1 – generation of the electrophile, NO2
• Step 2 – nucleophilic attack by arene to the electrophile
• Step 3 – regeneration of catalyst
• The carbonyl group is an electron withdrawing group (EWG) which
deactivates the benzene ring.
• Protonation of the ester carbonyl group by the solvent (H2SO4) increases
even further its EW effect
• The substitution occurs in meta position.
Procedure
1. In 125 mL Erlenmeyer flask, cool 12 mL of concentrated sulfuric acid to 0°C.
2. Add 6.1g (5.6 mL) of Methyl Benzoate to the 125 mL Erlenmeyer flask, then
added an additional 4 mL of sulfuric acid dropwise, and then added 4 mL of Nitric
acid.
3. Make sure to keep the solution cool in an ice bath to reach 5-15°C for 5-10
minutes.
4. Pour solution over 50 g of ice.
5. Collect product using vacuum filtration and washed crystals with minimum
amount of cold distilled water.
6. Dried product under vacuum for 10 minutes, and weighed product.
7. Calculate percent yield.
8. Obtain melting point and IR spectrum of sample
Nitration of Methyl Benzoate
• Electrophilic aromatic substitution is electrophilic because of the high
density in the benzene ring, which is one of the components in the
experiment.
• Benzene ring is one of the most important natural products and other
useful products.
• Nitration is an important example of electrophilic substation. In this
experiment, the electrophile in nitration is the nitronium ion which is
coming from the nitric acid by pronation and loss of water, using
sulfuric acid as the dehydrating agent.
Overall Reaction
• In this experiment, methyl benzoate will be reacted with nitric acid using
sulfuric acid as the catalyst.
• The nitration of a benzene ring is an electrophilic aromatic substitution
reaction,
• Step 1 – generation of the electrophile, NO2
• Step 2 – nucleophilic attack by arene to the electrophile
• Step 3 – regeneration of catalyst
• The carbonyl group is an electron withdrawing group (EWG) which
deactivates the benzene ring.
• Protonation of the ester carbonyl group by the solvent (H2SO4) increases
even further its EW effect
• The substitution occurs in meta position.
Procedure
1. In 125 mL Erlenmeyer flask, cool 12 mL of concentrated sulfuric acid to 0°C.
2. Add 6.1g (5.6 mL) of Methyl Benzoate to the 125 mL Erlenmeyer flask, then
added an additional 4 mL of sulfuric acid dropwise, and then added 4 mL of Nitric
acid.
3. Make sure to keep the solution cool in an ice bath to reach 5-15°C for 5-10
minutes.
4. Pour solution over 50 g of ice.
5. Collect product using vacuum filtration and washed crystals with minimum
amount of cold distilled water.
6. Dried product under vacuum for 10 minutes, and weighed product.
7. Calculate percent yield.
8. Obtain melting point and IR spectrum of sample
1
Jude FanFan
Kean University
Organic Chemistry II Lab
2
Experiment:
Identifying SN1 and SN2 Reactions of Alkyl Halides
Objective:
The objective of this experiment was to identify SN1 and SN2 reactions of alkyl halides.
Materials and Methods:
Five 10 x 75 mm test tubes were labeled and 0.1 mL of the following halides were placed in each
test tube: 1-chlorobutane, 2-chlorobutane, 2-chloro-2-methyl propane, bromobenzene, and 2bromobutane. To each test tube, 1 mL of 18% sodium iodide in acetone and 1 mL of 1% silver
nitrate in ethanol were added. The test tubes were mixed and the time of precipitate formation
was recorded. If no reaction occurred within 5 minutes, the test tubes were placed in a 50°C
water bath and observed for any reaction over the next five to six minutes. After the experiment,
the test tubes were emptied into a halogenated waste container.
Results:
The results of the experiment are shown in Table 1.
Table 1: Results of SN1 and SN2 Reactions of Alkyl Halides
Halide Reagent
Time (min)
1-chlorobutane
18% sodium iodide in acetone
5
2-chlorobutane
18% sodium iodide in acetone
5
3
2-chloro-2-methyl propane
18% sodium iodide in acetone
5
Bromobenzene
18% sodium iodide in acetone
No reaction
2-bromobutane
18% sodium iodide in acetone
No reaction
1-chlorobutane
1% silver nitrate in ethanol
No reaction
2-chlorobutane
1% silver nitrate in ethanol
No reaction
2-chloro-2-methyl propane
1% silver nitrate in ethanol
No reaction
Bromobenzene
1% silver nitrate in ethanol
No reaction
2-bromobutane
1% silver nitrate in ethanol
No reaction
Discussion:
The results of this experiment indicate that the 18% sodium iodide in acetone reacted with the
primary and secondary alkyl halides (1-chlorobutane, 2-chlorobutane, and 2-chloro-2-methyl
propane), but not the tertiary alkyl halides (bromobenzene and 2-bromobutane). This suggests
that the reaction between the halides and 18% sodium iodide in acetone is a SN2 reaction. The
results also show that none of the halides reacted with the 1% silver nitrate in ethanol, which
suggests that this reaction is a SN1 reaction.
4
Conclusion:
The results of this experiment indicate that the 18% sodium iodide in acetone reacts with the
primary and secondary alkyl halides and is a SN2 reaction, and the 1% silver nitrate in ethanol
does not react with any of the halides and is a SN1 reaction.