Yan Name and Maryott — Chlorination of Benzene. 169 



according to the above calculations, a ten per cent current 

 yield would produce. Such effects, if present, could not be 

 wholly masked by experimental errors, and would be plainly 

 evident in the curves of fig. 2. From their absence we may 

 conclude that if electrolytic chlorination played any part in 

 the results, the current yield was below ten per cent. 



One other point remains to be considered ; the possible influ- 

 ence of cathodic reduction. A test of benzene hexachloricle* 

 was carried out by dissolving 3 grams of this substance with 

 15 grams of sodium acetate in 200 cc of acetic acid, and elec- 

 trolyzing with 0*2 ampere, using the same cell as in the 

 experiments just described. After 14 hours 10 cc of the solution 

 gave with silver nitrate '0058 gram of silver chloride, a current 

 yield of about 1*5 per cent. The reduction is therefore very 

 slow. ISTo reduction of either monochlor- or p-clichlorbenzene 

 was produced under similar conditions. 



It is, therefore, probable that a small amount of reduction, 

 affecting only the addition chlorine, actually took place in 

 experiments 1-4. This is confirmed by the fact that in experi- 

 ment 4 the percentage of addition chlorine shows a slight fall 

 during each electrolytic period. A simple calculation, based 

 on the magnitude of this depression, proves, however, that the 

 effect of the cathode reduction upon the values of the velocity 

 constants was almost negligible and not such as to demand any 

 modification of our previous conclusions. 



In the hope of subsequently identifying the principal reaction 

 products, the liquid remaining at the close of experiments 2, 3 

 and 4 had been in each case shaken with aqueous sulphurous acid 

 and the benzene layer preserved. Fractional distillation of the 

 combined liquids so obtained gave monochlorbenzene, but no 

 certain indication of dichlorbenzene. From the oily residue a 

 small quantity of crystals separated which proved to consist 

 largely of the beta modification of benzene hexachloride. An 

 analysis of O04 grm. gave 72*68 per cent of chlorine; theory 

 for C 6 H 6 C1 6 , 73-17 per cent. 



Summary. 



1. Electrolysis of benzene in a solution of lithium chloride 

 in glacial acetic acid gave chlorinated benzenes with current 

 yields, under favorable conditions, of 50 to 70 per cent. Both 

 addition and substitution chlorine were present in the product, 

 the latter predominating. There was, however, nothing to show 

 that the effects were not due to the secondary action of chlorine 

 previously set free by the current and dissolved in the liquid. 



*The sample used had a melting point of 157° (corr.) and therefore consisted 

 almost exclusively of the a form. 



Am. Jour. Sci.— Fourth Series, Vol. XXXV, No. 206.— February, 1913. 



12 



