benzaldehyde

Benzaldehyde is an organic compound with the formula C7H6O and the IUPAC name benzenecarbaldehyde. It is the simplest aromatic aldehyde, consisting of a benzene ring bearing a formyl group. It is a colorless, flammable liquid with a characteristic almond-like odor. Its molecular weight is 106.12 g/mol, with a boiling point around 179°C and a melting point near -26°C. It is slightly soluble in water and is more soluble in many organic solvents.

Occurrence and production

Benzaldehyde occurs in trace amounts in some natural products, such as bitter almonds and apricot kernels. Industrial production is typically by the oxidation of toluene or of benzyl alcohol. Partial oxidation is often used to obtain benzaldehyde selectively, with benzoic acid as a common competing product. It can also be prepared by oxidation of benzyl alcohol under appropriate conditions.

Uses

Benzaldehyde is widely used as a flavor and fragrance ingredient, contributing an almond-like aroma to foods, perfumes, and cosmetics. It serves as a versatile industrial intermediate for the synthesis of benzoic acid, mandelic acid, benzyl alcohol, and various fragrances and dyes. In the lab, it participates in reactions such as the benzoin condensation, Schiff base formation with amines, and various nucleophilic additions at the aldehyde group.

Reactions and properties

The aldehyde group undergoes typical reactions: reversible oxidation to benzoic acid, reduction to benzyl alcohol, and formation of cyanohydrins or imines. The aromatic ring is deactivated toward electrophilic substitution relative to benzene, and substituents on the ring influence reactivity accordingly.

Safety and handling

Benzaldehyde is flammable and can cause irritation to skin, eyes, and the respiratory tract. It should be stored in a cool, well-ventilated area away from oxidizers, with appropriate protective equipment to minimize exposure.