Question

\(\mathrm{OH}^{-}\)is a very poor leaving group. However, many alcohols react with alkyl or aryl sulfonyl chlorides to give sulfonate esters.

Short answer

Answer: The purpose of converting an alcohol to a sulfonate ester in the reaction with alkyl or aryl sulfonyl chloride is to improve the leaving group's stability, making it more reactive for further reactions, such as substitution or elimination reactions. The final product is a sulfonate ester, which is widely used in organic synthesis to form other functional groups or molecules.

Step-by-step solution

Identify the reactants

In the reaction under consideration, the reactants are an alcohol and an alkyl or aryl sulfonyl chloride. The alcohol has an OH group, which is a poor leaving group. The sulfonyl chloride will convert the alcohol's OH group into a better leaving group.

Sulfonate ester formation mechanism

The reaction involves a nucleophilic substitution (SN2) mechanism, where the oxygen atom of the alcohol acts as a nucleophile and attacks the sulfur atom of the alkyl or aryl sulfonyl chloride. This leads to the breaking of the sulfur-chlorine bond and the formation of a sulfonate ester.

Understanding the role of the sulfonate ester

The sulfonate ester formation increases the stability of the leaving group, converting OH⁻ into a good leaving group. This is because the sulfur atom in the sulfonate ester has more electron-withdrawing capability than the oxygen atom, which stabilizes the negative charge of the leaving group. The good leaving group enhances the reactivity of the compound for further reactions, such as substitution or elimination reactions.

Final product and its uses

The final product of the reaction is a sulfonate ester, which is more reactive than the initial alcohol. Sulfonate esters are widely used in organic synthesis, as they can be further reacted to form other functional groups or molecules. This reaction with alcohols and alkyl or aryl sulfonyl chlorides is a common method to prepare sulfonate esters, which then undergo various transformations, depending on the desired outcome in organic synthesis.