aldehidit

Aldehidit is the plural term used in Finnish for aldehydes, a class of organic compounds characterized by a carbonyl group bound to at least one hydrogen atom. The general structural formula is R‑CHO, where R can be a hydrogen, alkyl, aryl or heteroalkyl group. Aldehydes are derived from the oxidation of primary alcohols, the dehydrogenation of alcohols, or the reduction of carboxylic acid derivatives such as acid chlorides, anhydrides, and esters. Common synthetic routes include the Perkin, Sommelet–Hauser, and Thiyl radical reactions, which enable the introduction of various substituents.

The carbonyl group in aldehydes imparts distinctive chemical behavior. Aldehydes are more reactive than ketones toward nucleophilic addition due to the lack of steric hindrance and the presence of a hydrogen atom, which stabilizes the transition state. They participate in reactions such as the aldol condensation, Cannizzaro reaction, and the formation of oximes, hydrazones, and thioamides. The Sn1k mechanism allows the electrophilic addition of nucleophiles to the carbonyl carbon. Aldehydes also undergo oxidation to carboxylic acids, typically by mild oxidizing agents such as PCC or Dess–Martin periodinane.

In industrial and laboratory settings, aldehydes serve as intermediates, solvents, fragrances, and flavoring agents. Formaldehyde, acetaldehyde, and benzaldehyde are among the most widely used examples. In biology, many aldehydes are naturally occurring or generated during metabolic processes. Elevated aldehyde levels, particularly 4-hydroxynonenal and malondialdehyde, are markers of oxidative stress and have been linked to various diseases, including neurodegenerative disorders and cancer. For safety, aldehydes are often handled as aerosols or vapor mixtures and stored in cool, well-ventilated areas to mitigate their volatility and toxicity.