Aldehydes

Definition

Aldehydes are organic compounds characterized by the presence of a carbonyl group ($C=O$) bonded to at least one hydrogen atom. They have the general formula $RCHO$, where $R$ can be a hydrogen atom or any alkyl or aryl group.

5 Must Know Facts For Your Next Test

1. Aldehydes undergo nucleophilic addition reactions due to the electrophilic nature of the carbonyl carbon.
2. The simplest aldehyde is formaldehyde, with the chemical formula $HCHO$.
3. Aldehydes can be oxidized to carboxylic acids using oxidizing agents such as potassium permanganate ($KMnO_4$) or chromic acid ($H_2CrO_4$).
4. In naming aldehydes, the suffix '-al' is used, and the parent hydrocarbon chain must include the carbonyl group's carbon atom.
5. Aldehydes generally have higher boiling points than alkanes and ethers but lower than alcohols due to dipole-dipole interactions.

Review Questions

• What is the general formula for an aldehyde?
• How does an aldehyde differ from a ketone in terms of structure?
• What type of reaction do aldehydes typically undergo due to their electrophilic carbonyl carbon?

Related terms

Ketone:

An organic compound with a carbonyl group ($C=O$) bonded to two alkyl or aryl groups. They have the general formula $RCOR'$.

Carboxylic Acid:

Organic compounds containing a carboxyl group ($-COOH$). They can be formed by oxidizing aldehydes.

Ester: Derived from carboxylic acids and alcohols, esters have the functional group $RCOOR'$ and are known for their pleasant fragrances.