aldehydejä

Aldehydejä are a class of organic compounds that contain a carbonyl group bonded to at least one hydrogen, giving the general structure R-CHO. The carbonyl carbon is highly electrophilic, which drives many of the characteristic reactions of aldehydes. They can be produced by the selective oxidation of primary alcohols, or by methods such as hydroformylation of alkenes or partial oxidation of larger carbonyl compounds.

Common examples include formaldehydes (H2C=O, the simplest aldehyde), acetaldehyde (CH3CHO), and benzaldehyde (C6H5CHO). Aldehydes are typically polar and can have relatively high reactivity for their size, with boiling points that rise with increasing molecular weight. In water, some aldehydes, notably formaldehyde, form hydrates (gem-diols), while others remain predominantly in the non-hydrated form.

Reactions of aldehydes center on the carbonyl group. They readily undergo nucleophilic addition, leading to alcohols after reduction or to hemiacetals and acetals with alcohols and diols. Aldehydes can be oxidized further to carboxylic acids, though mild oxidants favor aldehyde formation. They participate in Tollens’ and Fehling’s tests, which differentiate aldehydes from most ketones by redox behavior. Aldehydes also engage in aldol condensations when α-hydrogens are present, a key reaction in organic synthesis.

Applications are diverse: formaldehyde and other aldehydes are used as solvents, precursors in polymers and resins, flavor and fragrance additives, and intermediates in pharmaceutical and agrochemical syntheses. Safety considerations include irritation and potential toxicity; some aldehydes, especially formaldehyde, are regulated due to health concerns.