Question

please help me!!

Rearrangen 3. (6) Give the mechanistic symbols (SN1, S 2, El, or E2) that are most consistent with each of the following statements. If none of them apply, write N. More than one symbol may be true for each statement (list all that apply), 1-bromopentane reacts faster than 3-bromo-2,4-dimethylpentane by this/these mechanism(s). Corresponds to the reaction profile at the right. Which mechanism gives a racemic mixture of substitution products?

Answer 1

3.

S_N2

The electrophilic center of 1-bromobepentane is less sterically crowded than 3-bromo-2,4-dimethylpentane. Hence, 1-bromopentane reacts faster by S_N2 mechanism.

사 Br 3-bromo-2,4-dimethylpentane 1-bromopentane

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S_N1 and E1

The energy profile diagram shows two humps or transition states. This implies that the reaction mechanism involves two steps and an intermediate. Both S_N1 and E1 mechanisms involve two steps and a carbocation intermediate.

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S_N1

S_N1 mechanism goes through a carbocation intermediate. Carbocations are planar. They can get attacked from both sides of the plane equally. Hence, S_N1 at a stereocenter gives racemic mixture.