AROMATIC COMPOUNDS 253 



Benzal Chloride, QH 5 . CHC1 2 . 



This compound is prepared by the further action of chlorine upon 

 boiling toluene, until chlorine corresponding to the equation, 



C 6 H 5 . CH 3 + 2 C1 2 = C 6 H 5 CHC1 2 + 2 HC1, 

 has been absorbed. 



It can be obtained by the action of phosphorus pentachloride upon 

 benzaldehyde : 



C 6 H 5 . CHO + PC1 5 = C 6 H 5 CHC1 2 + POC1 3 . 



Benzal chloride is a colourless liquid of boiling-point 206 ; it is 

 also used for making benzaldehyde. 



Benzotrichloride, C 6 H 5 . CC1 3 , or Phenylchloroform. 



By the further action of chlorine upon toluene, benzotrichloride is 

 formed : 



C 6 H 5 CH 3 + 3 C1 2 = C 6 H 5 CC1 3 + 3 HC1. 



It is a liquid which boils at 213 and is converted into benzoic acid by 

 boiling with water. 



Benzyl Alcohol, C 6 H 5 . CH 2 OH. 



Benzyl alcohol occurs as such and also as ester with benzoic and 

 cinnamic acids in the resin storax, in balsam of Tolu and balsam of 

 Peru. 



It is the chief type of an aromatic alcohol in which the 

 hydroxyl group is present in the side chain (compare phenol). 



Preparation. 



As an alcohol it may be obtained by reducing the corresponding 

 aldehyde, benzaldehyde : 



C 6 H 5 . CHO + H 2 = C 6 H 5 . CH 2 OH, 



or by the action of water and aqueous alkalies upon benzyl chloride : 

 C 6 H 5 CH 2 C1 + H 2 O = HC1 + C 6 H 5 . CH 2 OH. 



Benzyl alcohol is usually obtained by the action of aqueous po- 

 tassium hydroxide upon benzaldehyde : 



2 C 6 H 5 CHO + KOH = C 6 H 5 CH 2 OH + C 6 H 5 COOK. 



Benzaldehyde is shaken up with four times the amount of potash dissolved 

 in about an equal weight of water. The emulsion which is formed is allowed 

 to stand for twenty- four hours. On the addition of water, the potassium ben- 

 zoate dissolves ; the solution is extracted with ether, the ether dried and the 

 benzyl alcohol obtained by distillation. 



Properties. 



Benzyl alcohol is a colourless liquid of boiling-point 206 ; it is 

 not easily soluble in water, but dissolves in alcohol and ether. It 

 behaves like ethyl" alcohol with sodium and phosphorus pentachloride. 

 It forms esters with acids or acid anhydrides, etc., e.g. benzyl bromide, 

 benzyl acetate. 



