i am having trouble with the following question....
How would you expect the following series of compounds to compare in behavior in the two tests(Sn1 vs. Sn2):
1) CH3=CHCH2BR)
2) CH3C=CHCH3
!
Br
3) CH3CH2CH2Br
To compare the behavior of compounds in Sn1 (substitution nucleophilic unimolecular) versus Sn2 (substitution nucleophilic bimolecular) reactions, you need to consider the reaction mechanism and the characteristics of the compound.
In general, Sn1 reactions occur in two steps, where the leaving group first dissociates to form an intermediate carbocation, and then the nucleophile attacks the carbocation to replace the leaving group. Sn1 reactions are favored by polar protic solvents, weak nucleophiles, and good leaving groups. Additionally, Sn1 reactions often proceed through a rearrangement of the carbocation intermediate.
On the other hand, Sn2 reactions occur in a single step, where the nucleophile attacks the substrate while the leaving group is still attached. Sn2 reactions are favored by polar aprotic solvents, strong nucleophiles, and good leaving groups. Sn2 reactions do not involve carbocation intermediates and do not involve rearrangements.
Now, let's apply this knowledge to analyze the behavior of the given compounds in Sn1 and Sn2 reactions:
1) CH3CH=CHCH2Br:
In Sn1 reactions, the formation of a carbocation intermediate is more likely due to the presence of a double bond adjacent to the leaving group. This compound can undergo carbocation rearrangement, which is a characteristic feature of Sn1 reactions. However, the nucleophilicity of the compound may not be high due to the presence of a double bond. In Sn2 reactions, the primary carbon with the leaving group is more accessible, making it favorable for a nucleophilic attack. However, the double bond may hinder the approach of the nucleophile. Overall, this compound is expected to show a mixture of Sn1 and Sn2 behavior.
2) CH3C=CHCH3Br:
This compound does not have an adjacent leaving group or any reactive site for Sn1 reactions. In Sn2 reactions, the leaving group is attached to a tertiary carbon, which is not favorable due to steric hindrance. Thus, the compound is expected to show very limited reactivity in both Sn1 and Sn2 reactions.
3) CH3CH2CH2Br:
This compound has a primary carbon with the leaving group, making it suitable for Sn2 reactions. The absence of any adjacent reactive sites or steric hindrance suggests that Sn1 reactions are less likely. Therefore, the compound is expected to predominantly undergo Sn2 reactions.
Remember, these predictions are based on general trends and characteristics. The actual behavior of compounds in Sn1 and Sn2 reactions can be influenced by various factors like temperature, concentration, and the nature of the solvent.