benzaldehyde

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benzaldehyde

(bĕnzăl`dəhīd) or

benzenecarbonal

(bĕn'zēnkär`bənəl), C6H5CHO, colorless liquid aldehydealdehyde
[alcohol + New Lat. dehydrogenatus=dehydrogenated], any of a class of organic compounds that contain the carbonyl group, , and in which the carbonyl group is bonded to at least one hydrogen; the general formula for an aldehyde is RCHO, where R is hydrogen
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 with a characteristic almond odor. It boils at 180°C;, is soluble in ethanol, but is insoluble in water. It is formed by partial oxidation of benzyl alcohol, and on oxidation forms benzoic acid. It is called oil of bitter almond, since it is formed when amygdalin, a glucoside present in the kernels of bitter almonds and in apricot pits, is hydrolyzed, e.g., by crushing the kernels or pits and boiling them in water; glucose and hydrogen cyanide (a poisonous gas) are also formed. It is also prepared by oxidation of toluene or benzyl chloride or by treating benzal chloride with an alkali, e.g., sodium hydroxide. Benzaldehyde is used in the preparation of certain aniline dyes and of other products, including perfumes and flavorings.

Benzaldehyde

 

an organic compound, C6 H5 CHO; a colorless, oily liquid with the odor of bitter almonds; Tm = –26° C; Tb = 179° C. Benzaldehyde dissolves in water in the proportions of 0.3 g : 100 g; it is miscible with alcohol, ether, and other organic solvents. Benzaldehyde is easily oxidized (even in air) into benzoic acid, C6H5COOH; however, the addition of 0.1 percent hydroquinone inhibits oxidation. Benzaldehyde combines with sodium bisulfite, hydrocyanic acid, and other molecules by a CO bond. When benzaldehyde is boiled with an alkaline solution, benzyl alcohol and benzoic acid are formed (the Cannizzaro reaction). In the presence of the CN ion, benzaldehyde enters into benzoin condensation. The condensation of benzaldehyde with acetaldehyde under the action of a base yields cinnemal-dehyde, C6H5CH=CHCHO; condensation with phenols and aromatic amines yields derivatives of triphenylmethane.

Benzaldehyde in the form of a glycoside of amygdalin, which breaks down in water to form benzaldehyde, glucose, and hydrocyanic acid, is contained in the pits of bitter almonds and apricots, peaches, and other fruits. Benzaldehyde is obtained by the oxidation of toluene or the hydrolysis of benzylidene chloride, C6H5CHCl2. The method of obtaining benzaldehyde from benzene and carbon monoxide under the action of aluminum chloride is of great significance. Benzaldehyde is used as a fragrant substance, for the synthesis of cinnemaldehyde and benzoin, and in the production of dyes of the triphenylmethane series.

IA. F. KOMISSAROV

benzaldehyde

[benz′al·də‚hīd]
(organic chemistry)
C6H5CHO A colorless, liquid aldehyde, boiling at 170°C and possessing the odor of bitter almonds; used as a flavoring agent and an intermediate in chemical syntheses.