Aldehyder

Aldehyder are a class of organic compounds characterized by the presence of a formyl group, CHO, attached to a hydrogen, alkyl, or aryl group. The general structural motif is R-CHO, where R represents an alkyl or aryl substituent. In IUPAC naming, most members are called aldehydes and use the suffix -al (for example, methanal, ethanal, benzaldehyde). The formyl group makes aldehydes distinct from ketones, which have two carbon substituents on the carbonyl carbon.

Key properties include a polarized carbonyl group, which makes aldehydes reactive toward nucleophiles and susceptible to oxidation to carboxylic acids and to reduction to primary alcohols. Aldehydes are typically more reactive than ketones due to the presence of the hydrogen on the carbonyl carbon. Many small aldehydes are volatile and soluble in water to varying degrees; solubility decreases with increasing carbon chain length.

Industrial production and occurrence: aldehydes are produced by several routes. A common method is the oxidation of primary alcohols (for example, methanol to formaldehyde, ethanol to acetaldehyde). The oxo (hydroformylation) process converts alkenes to aldehydes with one additional carbon. aldehydes such as formaldehyde, acetaldehyde, and benzaldehyde are also investigated and employed in the synthesis of resins, plastics, flavorings, and fragrances.

Uses: aldehydes serve as precursors to polymers, lubricants, and specialty chemicals. They are key intermediates in the manufacture of plastics, resins, plasticizers, and textiles, as well as in fragrance and flavor industries. Some aldehydes are used as solvents or disinfectants, though many are toxic or irritants.

Safety: aldehydes can be volatile and irritating to the eyes, skin, and respiratory system. They may be toxic in higher exposures and require appropriate handling and controls in industrial settings.