Question

Rank the relative rates of the following alkyl halides in an SN1 reaction?

1) Methyl bromide
2) Ethyl bromide
3) Propyl bromide
4) Isopropyl bromide
5) Butyl bromide

Answer 1

The relative rates of alkyl halides in an SN1 reaction increase with increasing carbocation stability: tertiary > secondary > primary > methyl.

Step-by-step explanation:

The relative rates of the alkyl halides in an SN1 reaction can be determined based on the stability of the carbocation intermediate formed during the reaction. In general, the rate of reaction increases as the stability of the carbocation increases. Therefore, the ranking of the alkyl halides in an SN1 reaction would be as follows:

1. Tertiary alkyl halide (such as t-butyl bromide)
2. Secondary alkyl halide (such as isopropyl bromide)
3. Primary alkyl halide (such as propyl bromide)
4. Methyl halide (such as methyl bromide)

Butyl bromide would have a similar reactivity as propyl bromide as both are primary alkyl halides. It is important to note that this ranking is based on the assumption that the nucleophile concentration is in excess.