aldehydien

Aldehydien is a term that may appear in various languages or older texts as a reference to aldehydes, a broad class of organic compounds that contain a carbonyl group bonded to at least one hydrogen atom. The standard English term for this class is aldehyde, with the plural aldehydes. The defining functional group is the aldehyde group, –CHO, where the carbonyl carbon is bonded to one hydrogen and one other substituent (R).

Aldehydes are typically polar and moderate in size, which gives them distinctive reactivity and distinctive physical properties. They generally form higher-boiling liquids than alkanes of comparable molecular weight due to dipole-dipole interactions, yet they do not form the strong hydrogen-bond networks seen in alcohols. Common examples include formaldehyde (H2C=O), acetaldehyde (CH3CHO), and benzaldehyde (C6H5CHO). Many aldehydes have characteristic, often pleasant, aromas and are important in industry and biology.

Synthesis and reactions of aldehydes are central to organic chemistry. They can be prepared by oxidation of primary alcohols or by hydroformylation (oxo-process) of alkenes. Aldehydes are readily oxidized to carboxylic acids and can be reduced to primary alcohols. They also participate in nucleophilic additions to form hemiacetals with alcohols, and undergo aldol reactions with enolates from other carbonyl compounds, producing β-hydroxy carbonyl compounds. Aldehydes can be further functionalized to a wide range of products.

Applications and safety: aldehydes are widely used in resin production, fragrances, and flavorings. Some, notably formaldehyde, are toxic and irritant, requiring careful handling and storage. The chemistry of aldehydes is foundational in both laboratory research and industrial synthesis.