aldehydu

Aldehyde is an organic compound defined by the presence of a formyl group, a carbonyl group bonded to at least one hydrogen atom, typically at the end of a carbon chain. The general formula is R-CHO, where R can be a hydrogen atom or an alkyl or aryl group. The carbonyl carbon is highly polar, making aldehydes reactive toward nucleophiles and oxidants.

Common examples include formaldehyde (methanal, H2C=O), acetaldehyde (ethanal, CH3CHO), and benzaldehyde (C6H5CHO). Formaldehyde is the simplest aldehyde and is a gas at room temperature; acetaldehyde and benzaldehyde are liquids with characteristic odors. Aldehydes can be distinguished from ketones by their tendency to undergo oxidation to carboxylic acids and by their reactivity in certain qualitative tests.

Reactivity and reactions: aldehydes undergo nucleophilic addition at the carbonyl carbon. They can be oxidized to carboxylic acids (formic acid from formaldehyde, acetic acid from acetaldehyde) and reduced to primary alcohols (e.g., formaldehyde to methanol, acetaldehyde to ethanol). They can hydrate in water to form gem-diols and participate in condensation reactions, including aldol condensations. Tollens’ test and similar assays exploit the aldehyde’s reducing ability to distinguish aldehydes from ketones.

Industrial and practical relevance: aldehydes are produced by oxidation of primary alcohols and serve as solvents, flavors, fragrances, and monomers for plastics and resins. Safety considerations include irritation and, for some, carcinogenic concerns (notably formaldehyde).

In Polish, aldehyde is aldehyd, and aldehydu is its genitive singular form, reflecting standard grammatical usage.