Toluene chloride

It was first described in 1608 when it was sublimed out of gum benzoin. It also occurs in many other natural resins. Benzoic acid is manufactured by the air oxidation of toluene in the liquid phase at 150°C and 4-6 atm. in the presence of a cobalt catalyst by the partial decarboxylation of phthalic anhydride in either the liquid or vapour phase in the presence of water by the hydrolysis of benzotrichloride (from the chlorination of toluene) in the presence of zinc chloride at 100°C. 

The benzene used in this preparation should be reasonably free from toluene therefore use a sample of benzene supplied by dealers as crystalUsable benzene, i.e.y one which crystallises readily when cooled in ice-water. It should preferably be dried over calcium chloride and, immediately before use, filtered through a fluted filter-paper. The pyridine should also preferably be dried over solid potassium hydroxide and redistilled. 

In the following preparation, the oxidation of benzyl chloride instead of toluene is therefore given in order to reduce the time required. It should be borne in mind, however, that the procedure is othenvise independent of the nature of the side chain. 

Although benzenesulphonyl chloride has for simplicity been used in the above discussion, tolucne-/>- sulphonyl chloride, CHaCeH SO Cl, is more frequently used in the laboratory, owing to its much lower cost, the latter being due in turn to the fact that toluene-p-sulphonyl chloride is a by-product in the commercial preparation of saccharin. Toluene-p sulphonyl chloride is a crystalline substance, of m.p. 68° the finely powdered chloride will, however, usually react readily with amines in the Schotten-Baumann reaction it does not react so readily with alcohols, but the reaction may be promoted considerably by first dissolving the chloride in some inert water-soluble solvent such as acetone. 

Required Phenol, 0-4 g. 10% sodium hydroxide, 2-5 ml. toluene-/)-sulphonyl chloride, 0-9 g. acetone, 4 ml. 

Toluene p ulphonyl chloride reacts with aqueous ammonia to give the... 

Required Toluene-/)-sulphonyl chloride, 5 g. ammonium carbonate, 10 g. 

The p-methylacetophenone is readily prepared by the Friedel-Crafts reaction cf. p. 254), toluene being treated with acetyl chloride in the presence of alumfnium chloride. The toluene is employed in considerable excess so that it... 

METHYLACETOPHENONE. Required Toluene, 250 ml. acetyl chloride, 35 ml. aluminium chloride, 40 g. 

During this period hydrogen chloride continues to be liberally evolved, and the product darkens considerably in colour. Now pour the product cautiously into 500 ml. of dilute hydrochloric acid and 100 g. of chipped ice in a separating-funnel, and shake the mixture thoroughly this operation removes the dark colour, and the toluene solution becomes yellow. Run off the lower acid layer, and extract the toluene three times with water. Finally dry the toluene solution over calcium chloride. 

A) Toluene -sulphonates. For directions, using an acetone solution of toluene-/) Sulphonyl chloride, see p. 249 use o 3-o 5 g. of the phenol. Note that the chloride should be dissolved in a minimum of acetone, otherwise separation of the ester may be slow and incomplete. 

Z>) Toluene-p-sulphonylotion (p. 247). Proceed as in 3(a), but using 1 5 g of toluene-p-sulphonyl chloride, either finely pow dered or in concentrated acetone solution. Note. The sulphonyl derivative of a primary amine is soluble in aqueous sodium hydroxide, and the final solution must be diluted and acidified to precipitate the product. Recrystallise and take the m.p. (M.ps., pp. 550-551.)... 

Benzene-sulphonylotion. Benzene-sulphonyl chloride, which can be used in place of toluene-/>-sulphonyl chloride, is liquid at room temperature and consequently reacts rapidly when the reaction mixture (as in 3(a)) is vigorously shaken. In general, however, the toluene-/>-sulphonyl derivatives crystallise even more readily than the benzene-sulphonyl analogues, and have lower solubilities and higher m.ps. 

C) Benzoyl and Toluene-sulphonyl Derivatives. Proceed as in (3) above, using benzoyl or toluene p-sulphonyl chlorides benzene"Sul-phonyl chloride can be similarly used (see 3 above). (M.ps., pp. 550 -551.)... 

Toluene. Toluene, e from sulphur compounds, may be purchased. If required dry, it is treated with anhydrous calcium chloride, followed by sodium wire (see under Benzene, 15). 

The distillate contains alcohol, toluene and water, and may be dried with anhydrous potassium carbonate and used again for esterification after the addition of the necessary quantity of alcohol alternatively, the toluene may be recovered by washing with water, drying with anhydrous calcium chloride or anhydrous magnesium sulphate, and distiUing. 

In the absence of catalysts, toluene when treated with chlorine (or bromine) at the boiling point, preferably with exposure to sunlight or other bright light source, undergoes halogenation in the side chain. The entrance of the first chlorine atom, for example, proceeds at a much faster rate than the entrance of the second chlorine atom so that in practice the major portion of the toluene is converted into benzyl chloride before appreciable chlorination of benzyl chloride occurs ... 

Rapid side-chain chlorination of toluene proceeds in the dark with sulphuryl chloride in the presence of dibenzoyl peroxide (0-001-0 005 mol per mol of SOjCl,) as catalyst ... 

Method 2. In a 500-ml. rovmd-bottomed flask, fitted with an efficient reflux condenser, place 92 g, (106 ml.) of toluene, 68 g. (41 ml.) of redistilled sulphuryl cldoride and 1 g, of dibenzoyl peroxide (Section IV,196). Reflux gently, when a vigorous reaction takes place the reaction is complete in 30 minutes. Isolate the benzyl chloride as described in Method 1. The yield is 50 g. 

Benzal chloride (benzylidene chloride). Use 100 g. of toluene and continue the passage of chlorine imtil the increase in weight of the flask and contents is 74 g. or, alternatively, until the temperature rises to 187°, Collect the benzal chloride at 204 208° or at 104 105°/30 mm. Pure benzylidene chloride has b.p. 206°,... 

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