Based on the \" sn2 reactions with NaI\" table below: please answer the followin

Question

Based on the " sn2 reactions with NaI" table below:

please answer the following questions:

1.) looking at entries 1, 3 and 5, what conclusion can you draw about the type of alkyl chloride employed (primary, secondary, or tertiary ) and the rate at which the sn2 reaction occurs? explain why this might be.
2.) looking at entries 2, 4 and 6 is the trend the same or different with alkyl bromides? does this result make sense?
3.) comparing the trend in the pairs of entries (1 vs 2) and (3 vs 4) and (5 vs 6), did the alkyl bromides react exactly the same as the alkyl chlorides? does one of them (bromides vs chlorides) react faster? explain why this might be.
4.) comparing entries 3 and 7, is there a difference in the rates? if there is, explain why there is a difference in the rate. (hint: thinking about the mechanism)
5.) comparing entries 1 and 8, is there a difference in rates? if there is, explain why this might be.
6.) why weren't alkyl iodides used in this part of the experiment? Hint: try and draw the reaction

Explanation / Answer

1).

Sodium iodide in acetone favours SN2 reactions.

For SN2 reactions the rate of reactivity is primary > secondary > tertiary

So here the reaction is faster for 1-chlorobutane which is a primary alkyl halide followed by 2-chlorobutane( secondary alky halide) and last 2-chloro-2-methyl propane ( tertiary alkyl halide)

So

  1> 3> 5

2).

2. 1-bromobutane – primary alky halide

4. 2- bromobutane – secondary alkylhalide

6. 2-bromo-2-methylpropane – tertiary alkylhalide

The trend is same for SN2 reactions

Primary > secondary > tertiary

So here the order is 2>4>6

The reaction alkybromides is faster than alkylchlorides

3).

1) vs 2)

1-chlorobutane and 1- bromobutane

The rate is higher for 1-bromobutane because Br- is a better leaving group

3) Vs 4).

The rate is higher for 2- bromobutane than 2-chlorobutane because Br- is a better leaving group

5) Vs 6)

For tertiary alkyhalides SN2 reaction is very slow.

Here no reaction with sodim iodide in acetone

4.

Chlorocyclohexane and 2-chloro butane are almost unreactive in NaI/ acetone. Among them the rate is very low for chlorocyclohexane because of steric hindrance.

Thus

3 > 7

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