Synthesis of benzyl chloride

Preparation of benzyl chloride

Preparation of benzyl chloride by chlorination of toluene with chlorine

Preparation of benzyl chloride

To the round bottom flask fitted with a reflux condenser, stirrer and gas inlet tube 100 g toluene and 5 g phosphorus pentachloride are placed. The flask before reaction is weighed. The reaction mixture is warmed to gentle boiling, and at the same time a rapid current of dry chlorine is passed in toluene. The chlorine is bubble until the weight of the flask have increased by about 35 g. The chlorine absorption is accelerated by the action of sunlight. Benzyl chloride is then fractionally distilled from unchanged toluene. The fractions passing over between  160-190° C is collected. In order to purify the product redistillation is applied. Colorless liquid with an irritating smell boiling point 176° C. The portions boiling above 185° C consist mostly of benzal chloride, C₆H₅CHCl₂, and phenylchloroform  C₆H₅CCl₃.

The war gases chemistry and analysis, by M. Sartory, 129, 1939.

Preparation of benzyl chloride by chlorination of toluene with chlorine without using phosphorus pentachloride

Device for the chlorination of toluene is shown below; it is placed in the window so that the sun’s rays fall directly onto the ball unit. Chlorination of toluene can be carried out also in the light of quartz lamp. The end of the reflux condenser is connected by means of tubes with the device for absorption of hydrogen chloride.

A glass apparatus for the preparation of benzyl chloride

The flask was charged with 200 g (about 2 moles) of toluene and heated in an oil bath to reflux. The vapors of toluene come through the tube 2 into the bowl, where it is mixed with chlorine. The resulting benzyl chloride is condensed and flows through the tube 1 back into the flask. Unreacted toluene is condensed in the reflux condenser and returned to the flask. When benzyl chloride is formed the boiling point of the liquid in the flask increases, the oil bath temperature should be raised gradually to reflux of the toluene. Chlorination is considered completed when the temperature of the oil bath reached 170-180° C and reflux of toluene stops. The reaction flask was disconnected and distillation column attached with Liebig condenser for the distillation of crude benzyl chloride. At first, unreacted toluene was distilled off, then the fraction boiling in the range 158-188° C and consisting mainly of benzyl chloride. Above a temperature of 188° C a small amount of distilled products higher chlorination. The fraction boiling at 158-188° C, is distilled again, collecting benzyl chloride, boiling at 176-181° C. Yield, 200 g (72% of theory).

Препаративная органическая химия, Вульфсон Н.С., 186-187, 1959 (Preparative organic chemistry, Wolfson N. S., 186-187, 1959)

preparation of benzyl chloride

To prepare the benzyl chloride a molar ratio of toluene to sulfuryl chloride of 1.2:1 is used. After the addition of 0.002 mole of benzoyl peroxide or, still better, azo-bis-isobutyronitrile (referred to 1 mole of sulfuryl chloride) the toluene and the sulfuryl chloride are heated to the boil in a round-bottomed flask with a very efficient reflux condenser and a calcium chloride tube. At intervals of 1 hr, the same amount of chain initiator is added. The reaction is complete in 8-10 hours and  when no further evolution of gas can be observed. The mixture is allowed to cool and is washed with water and it is then dried with magnesium sulfate and fractionated through a 20-cm Vigreux column yielding 80% of benzyl chloride, b.p. 61°C/10mm; n20/D 1.5390.

Organicum. Practical Handbook of Organic Chemistry, by Heinz Becker, Werner Berger and Günter Domschke, Addison-Wesley Pub. Co, 170, (1973)

Related Syntheses:

Synthesis of 2-chlorobenzyl chloride Synthesis of 2-methylbenzyl chloride Synthesis of 4-chlorobenzyl chloride Synthesis of benzal chloride Synthesis of 2-nitrobenzyl chloride