Based on the \"sn1 reactions with NaI\" and \"sn2 reactions with AgNO3\" experim

Question

Based on the "sn1 reactions with NaI" and "sn2 reactions with AgNO3" experiments table below to answer the following questions:

Sn2

Sn1

1.) is the trend in the reactivity between leaving groups (Br vs. Cl) the same or different between the Sn1 and Sn2 experiments? does this make logical sense to you? explain.
2a.) is the trend in the reactivity with different degrees of substitution (primary, secondary, and tertiary) the same or different between the Sn1 and Sn2 experiments? does this make logical sense to you? explain.
2b.) based on your answer to 2a, for which type of alkyl halide (primary, secondary or tertiary) will it be the most difficult to control the type of substitution reaction it undergoes?
3.) So Below are three sets of alkyl halides that you tried to compare, let's say for sn1 reaction. Which set would be a good, clear comparison ( so one that you can clearly tell something from)? which set will be the one that is not going to tell you anything conclusive? explain your answers.

Set A:

Set B:

Set C:

Explanation / Answer

1) The trend of leaving group activity is similar for -Cl and -Br. This is logical because, both type of reaction involved the C-halogen bond breaking.

2) The trend of reactivity with respect to degree of substitution is just opposite in SN1 and SN2 reaction. In SN1 reaction the order is 3^o>2^o>1^o . whereas in SN2 reaction it is 1^o>2^o>3^o. SN1 reaction involves a carbocation formation in the rate determining step of the reaction. Thus greater the stability of carbocation greater will be the rate of the reaction. Now, a tertiary carbocation is most stable due to greater number of hyperconjugative structures and +I effect of -alkyl substituents. For similar reason. asecondary carbocation is more stable that a primary carbocation.

SN2 reaction is a one step mechanism where the incoming nucleophile attacks from the back side of the alkyl halide (side opposite to the side from where leaving group leaves). greater the crowding at the reaction center , less will be the reaction rate. So, the reaction rate is 1^o>2^o>3^o.

2b. With secondary halides selectivity will be least as it has a equal tendency to undergo SN1 or SN2 reaction.

3. From Set C you can cleary decide which halide is a better leaving group.

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