# How does polarity affect SN1 reactions?

In ${S}_{N} 1$ reactions, there is a so-called carbocation intermediate. Solvents of higher polarity tend to stabilize these carbocations and therefore, ${S}_{N} 1$ reactions occur more readily in polar solvents.
For many problems in organic chemistry, it is often a good idea to take a look at the mechanism in question. Here is the mechanism for a general ${S}_{N} 1$ reaction.
The first step involves bromine as leaving group breaking away to generate the carbocation (positively charged carbon compound). Once the carbocation is formed, the $C {H}_{3} C {H}_{2} O H$ nucleophile quickly attacks at the positively charged carbon. Notice that since the first step is slow - namely, the formation of carbocation - it will determine the overall rate of the reaction. The more favorable the carbocation formation, the faster the rate of the overall ${S}_{N} 1$ reaction.