Benzaldehyde industrial preparation

Ethanediol. See Ethylene glycol Ethanoic acid. See Acetic acid Ethanol, 128, 130, 580-581 acidity of, 135, 740-741 and benzaldehyde, acetal from, 669 biological oxidation of, 600—602 chemical shifts, 606 conversion to diethyl ether, 592 dehydration of, 182 dipole moment of, 130, 863 by fermentation, 580-581 hydrogen bonding in, 130-131 industrial preparation of, 223, 581 physical properties of, 130, 132-133, 580 reduction of aryl diazonium salts by, 894, 907... 

On an industrial scale, cinnamaldehyde is prepared almost exclusively by alkaline condensation of benzaldehyde and acetaldehyde. Self-condensation of acetaldehyde can be avoided by using an excess of benzaldehyde and by slowly adding acetaldehyde [154]. 

One of the earliest perfumery materials to be produced industrially was benzaldehyde, prepared from toluene in 1866. In 1868 coumarin was first synthesized, soon to be followed by heliotropin, ionone, and vanillin. The first nitro musks appeared in 1888, and amyl salicylate in 1898. Since then, for the last hundred years, the history of perfumery has been dominated by the creation of new aromatic chemicals. 

This reaction, known as the Gatterman-Koch reaction, does not work with phenolic or amino aromatic species due to complex formation with the Lewis acid. It does work well with aromatic hydrocarbons and is used industrially to prepare benzaldehyde and, as here, p-tolualdehyde. 

The commercial value of this synthesis was increased when it was found that benzaldehyde could be prepared directly from toluene. Like the preceding synthesis of Baeyer, however, it has proved too expensive for a general industrial process though it is still used in some cases. 

Air oxidation of toluene gives predominantly benzoic acid. This is used in perfumery for the preparation of benzoate esters, benzo-phenone and various other compounds, but this use is dwarfed by the other industrial uses of benzoic acid. It is used in many different ways, for instance, as a precursor for nylon monomers. Crude benzoic acid contains a small amount of benzaldehyde, which is easily extracted from it. In view of the huge volume of benzoic acid produced, the volume of benzaldehyde recovered makes a substantial contribution to that used by the perfumery industry. 

Chlorination of toluene under radical conditions (either through the use of an initiator or by photolysis) gives a mixture of mono-, di- and trichlorotoluene. In practice in the perfumery industry, the reaction is run with an excess of toluene present, which means that benzyl chloride is the major product. A little benzal chloride is produced and can be separated and hydrolysed to give benzaldehyde. The major use of benzyl chloride is in the production of benzyl alcohol and its esters. The alcohol is produced by hydrolysis of the chloride. The esters can be prepared by esterification of the alcohol, but it is better economically to prepare... 

Aldehydes and ketones, which are produced by different methods and starting materials, are important carbonyl compounds that are widely used as such and for further processing [1], For example, cyclohexanone can be prepared upon cyclohexane oxidation, dehydrogenation of cyclohexanol at high temperature, or via catalytic oxidation of cyclohexanol under milder conditions. Acetophenone can be produced by the Hock process or be obtained via ethylbenzene oxidation with dioxygen, whereas benzaldehyde is produced industrially by toluene oxidation or by hydrolysis of benzal chloride in the presence of different acids and/or metal salts (i.e., tin(II), tin(IV), iron, or zinc chlorides) [1],... 

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