Sn2 Postlab

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Chemistry

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Cal Poly Pomona

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CHM 3140L

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CHM3140L

Dr. Osberger

2 Reaction

Part 1: Effect of Structure on the S

2 Reaction.

1. Draw the three reactions that you performed in this part of the laboratory.

2. Which reaction do you predict will be fastest? Which reaction will be slowest?

The fastest reaction would be that using 1-bromobutane, while the slowest would be with 2-methyl-2-

bromopropane

3. Carefully observe and record what compounds (and quantities) are added to each test tube. It may

help to make a table to record what was added to each test tube, and leave a space for your

observations of each reaction.

Test tube

Reagent

Substrate

2 mL 15% NaI

in acetone

2 drops 1-bromobutane

2 mL 15% NaI

in acetone

2 drops 2-bromobutane

2 mL 15% NaI

in acetone

2 drops 2-bromo-2-

methylpropane

4. In which tests tubes was a reaction observed? How could you tell?

In test tube 1 a reaction was observed. It could be determined by the formation of cloudiness.

In the other test tubes no reaction was observed

CHM3140L

Dr. Osberger

5. Were your predictions correct?

Yes, they exactly matched the experimental results.

6. Briefly summarize your observations for each test tube and how the results are consistent with the

trends in structure for each alkyl halide.

In test tube 1, the less steric hindered alkyl halide (1-bromobutane) reacted the fastest under SN2

conditions using sodium iodide as a nucleophile. This is due to the fact that the electrophilic carbon

attached to the bromine is open to an attack by the iodide anion. As he hydrogens attached to the

electrophilic carbon are substituted with methyl groups, the attack becomes increasingly difficult, slowing

the reaction and even not occurring at all.

Part 2: Effect of Sterics at the Beta-Position of the Alkyl Halide

7. Draw the two reactions that you performed in this part of the laboratory.

8. Which reaction do you predict will be fastest?

1-bromobutane would react faster than 2,2-dimethyl-1-bromopropane

9. Carefully observe and record what compounds are added to each test tube, and the observations

after each test tube has been allowed to react for 15 minutes. It may help to make a table to record

what was added to each test tube, and leave a space for your observations of each reaction.

Test tube

Reagent

Substrate

2 mL 15% NaI

in acetone

2 drops 1-bromobutane

2 mL 15% NaI

in acetone

2 drops 1-bromo-2,2-

dimethylbutane

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CHM3140L Dr. Osberger SN2 Reaction Part 1: Effect of Structure on the SN2 Reaction. 1. Draw the three reactions that you performed in this part of the laboratory. 2. Which reaction do you predict will be fastest? Which reaction will be slowest? The fastest reaction would be that using 1-bromobutane, while the slowest would be with 2-methyl-2bromopropane 3. Carefully observe and record what compounds (and quantities) are added to each test tube. It may help to make a table to record what was added to each test tube, and leave a space for your observations of each reaction. Test tube 1 2 3 Reagent 2 mL 15% NaI in acetone 2 mL 15% NaI in acetone 2 mL 15% NaI in acetone Substrate 2 drops 1-bromobutane 2 drops 2-bromobutane 2 drops 2-bromo-2methylpropane 4. In which tests tubes was a reaction observed? How could you tell? In test tube 1 a reaction was observed. It could be determined by the formation of cloudiness. In the other test tubes no reaction was observed CHM3140L Dr. Osberger 5. Were your predictions correct? Yes, they exactly matched the experimental results. 6. Briefly summarize your observations for each test tube and how the results are consistent with the trends in structure for each alkyl halide. In test tube 1, the less steric hindered alkyl halide (1-bromobutane) reacted the fastest under SN2 conditions using sodium iodide as a nucleophile. This is due to the fact that the electrophilic carbon attached to the bromine is open to an attack by the iodide an ...
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Tags: Experimental Results test tube fastest reaction leaving group electrophilic carbon