What is an aldol reaction and provide an example.

An aldol reaction is a type of organic reaction that involves the formation of a new carbon-carbon bond.

In an aldol reaction, a carbonyl compound (such as an aldehyde or ketone) reacts with an enolate ion (a compound with a negatively charged carbon atom adjacent to a carbonyl group) to form a beta-hydroxy carbonyl compound. This reaction is named after the products formed, which are aldehydes or ketones with both an alcohol (-OH) and aldehyde/ketone (-CO-) functional group.

For example, the aldol reaction can be used to synthesize aldol products such as 4-hydroxy-4-methylpentan-2-one. This involves the reaction of propanal with a base, such as sodium hydroxide, to form the enolate ion. The enolate ion then reacts with another molecule of propanal to form the beta-hydroxy carbonyl compound, which is the aldol product.

The aldol reaction is an important tool in organic synthesis, as it allows for the formation of complex molecules with multiple functional groups. It is also used in the production of pharmaceuticals, natural products, and other organic compounds. However, the reaction can be difficult to control, as it can lead to the formation of unwanted side products.