aldehydillä

Aldehydes are a class of organic compounds that contain a carbonyl group (C=O) bonded to a hydrogen atom and an R group. This R group can be another hydrogen atom (in the case of formaldehyde) or an alkyl or aryl group. The general formula for an aldehyde is RCHO.

The carbonyl group in aldehydes is polar due to the electronegativity difference between oxygen and carbon. This polarity influences the chemical and physical properties of aldehydes. They are generally more reactive than ketones, which have a carbonyl group bonded to two R groups. Aldehydes undergo nucleophilic addition reactions, where a nucleophile attacks the electrophilic carbon of the carbonyl group.

Formaldehyde (CH2O) is the simplest aldehyde and is a gas at room temperature. It is widely used in the production of plastics, resins, and as a preservative. Other common aldehydes include acetaldehyde (CH3CHO), propionaldehyde (CH3CH2CHO), and benzaldehyde (C6H5CHO), which has a characteristic almond-like smell and is used in flavorings and perfumes.

Aldehydes can be synthesized through various methods, including the oxidation of primary alcohols. Mild oxidizing agents are typically used to prevent further oxidation to carboxylic acids. They can also be produced by the reduction of esters or acyl chlorides.

Aldehydes play important roles in biological systems. For instance, acetaldehyde is an intermediate in ethanol metabolism. Many carbohydrates exist in ring-form structures that can open to reveal aldehyde or ketone functional groups.