noun
definition
A chemical compound (C6H5CHO) consisting of a benzene ring with an aldehyde substituent.
definition
Any of various derivatives of benzaldehyde.
example
benzaldehydes with polar substituents
Examples of benzaldehyde in a Sentence
With ammonia, benzaldehyde does not form an aldehyde ammonia, but condenses to hydrobenzamide, (C 6 H 5 CH) 3 N 2, with elimination of water.
The oxidation of benzaldehyde to benzoic acid when exposed to air is not one of ordinary oxidation, for it has been observed in the case of many compounds that during such oxidation, as much oxygen is rendered " active " as is used up by the substance undergoing oxidation; thus if benzaldehyde is left for some time in contact with air, water and indigosulphonic acid, just as much oxygen is used up in oxidizing the indigo compound as in oxidizing the aldehyde.
Benzaldoximes.-The a-oxime (benz-anti-aldoxime) is formed by the action of hydroxylamine on benzaldehyde.
It is prepared by oxidizing cinnamyl alcohol, or by the action of sodium ethylate on a mixture of benzaldehyde and acetaldehyde.
In 1832 he published, jointly with Willer, one of the most famous papers in the history of chemistry, that on the oil of bitter almonds (benzaldehyde), wherein it was shown that the radicle benzoyl might be regarded as forming an unchanging constituent of a long series of compounds obtained from oil of bitter almonds, throughout which it behaved like an element.
It can be prepared by the reduction of phenyl propiolic acid with zinc and acetic acid, by heating benzal malonic acid, by the condensation of ethyl acetate with benzaldehyde in the presence of sodium ethylate or by the so-called "Perkin reaction"; the latter being the method commonly employed.
In making the acid by this process benzaldehyde, acetic anhydride and anhydrous sodium acetate are heated for some hours to about 180 C., the resulting product is made alkaline with sodium carbonate, and any excess of benzaldehyde removed by a current of steam.
Benzaldehyde is a colourless liquid smelling of bitter almonds.
On account of the readiness with which it condenses with various compounds, benzaldehyde is an important synthetic reagent.
One of the earliest, if not the earliest, was the investigation, published in 1830, which proved the polymerism of cyanic and cyanuric acid, but the most famous were those on the oil of bitter almonds (benzaldehyde) and the radicle benzoyl (1832), and on uric acid (1837), which are of fundamental importance in the history of organic chemistry.
Distillation of its calcium salt gives benzophenone with small quantities of other substances, but if the calcium salt be mixed with calcium formate and the mixture distilled, benzaldehyde is produced.
Thus by using benzene, benzaldehyde and anthracene are obtained.
It combines with benzaldehyde, in the presence of hydrochloric acid, to form 2-benzyl-hydroquinone.
Chromic acid oxidizes it to benzoic acid and benzaldehyde.
It is an oily liquid, with an odour resembling that of benzaldehyde.
On reduction it yields hexahydrotoluene; oxidation with dilute nitric acid or chromic acid gives benzoic acid; whilst chromyl chloride and water give benzaldehyde.
Boiled with solution of potassium chromate and sulphuric acid, it evolves an odor of benzaldehyde.
They do not polymerize, and in the presence of caustic alkalies do not resinify, but oxidize to alcohols and acids (see Benzaldehyde for Cannizzaro's reaction).
In the case of aromatic aldehydes, acids are also obtained by means of " Cannizzaro's reaction " (see Benzaldehyde).
Chlorination in the cold gives orthoand para-chlortoluenes, but at the boiling point the side chain is substituted (see Benzaldehyde).