Perfume Ingredients Derived from Toluene

The alkylation of toluene to give hydrocinnamic derivatives is discussed in the previous section alongside the same reaction of benzene. 

Air oxidation of toluene gives predominantly benzoic acid. This is used in perfumery for the preparation of benzoate esters, benzophenone 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 and this is easily extracted from it. In view of the huge volume of benzoic acid produced, the volume of benzaldehyde recovered from it 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 

Claisen ester condensation gives cinnamic acid and its esters, the most important of which is methyl cinnamate, followed by benzyl cinnamate. 

cinnamaldehyde R = CjHn, amylcinnamic aldehyde R = C6H13, hexylcinnamic aldehyde 

Chlorination of toluene under radical conditions (either through the 

R = H cinnamaldehyde R = n-amyl amylcinnamic aldehyde R = n-hexyl hexylcinnamic aldehyde 

Addition of chloroform to benzaldehyde followed by esterification with acetic anhydride gives the trichloro derivative known as rose crystals or, more commonly by the misnomer, rose acetone. Such misnomers are not uncommon with older fragrance materials. Some 

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