158 Van Name and Maryott — Chlorination of Benzene. 



no porous cell was used, but on account of the slowness of this 

 reaction* and the low concentration of the hexachloride, its 

 effect upon the results must have been very small. 



In interpreting the results of Table I the following chlorina- 

 tion experiments, carried out under similar conditions but 

 without electrolysis, are important. A slow current of chlorine 

 gas was passed through the solution for the stated time in the 

 same cell used for the electrolytic experiments (fig. 1), the con- 

 denser and all exposed parts of the cell being carefully wrapped 

 in black paper to exclude light. 



Exp. 18. Solution : Acetic acidf 50 cc , benzene 50 cc , LiCl 

 about 3-5 grm. Temp. 15°. Time, 24 hours. Yield : Substi- 

 tution chlorine 1*856 grm., addition chlorine 1-1Y6 grm. (equiva- 

 lent to 61*3 and 38*7 per cent of the total chlorination, respec- 

 tively). 



Exp. 19. Solution as in Exp. 18. Temp. 80°. Time, 15 hours. 

 Yield : Substitution chlorine 2*939 grm., addition chlorine 0*866 

 grm. (7*7*2 and 22*8 per cent). 



Exp. 20. Solution : Acetic acid 120 cc , LiCl 6 grm., no benzene. 

 Temp. 110°. Time, 24 hours. Yield: 0*370 grm. of chlorine 

 substituted in the acetic acid. 



The formation of such considerable amounts of both substi- 

 tution and addition chlorine in experiments 18 and 19, under 

 conditions where actinic effects must have been negligible, can 

 only be ascribed to the lithium chloride, or to the acetic acid, 

 or to both. A hypothesis which seems to fit these and our 

 later results is that lithium chloride accelerates the substitution 

 process catalytically. LasarewJ has reported a similar effect 

 of the other alkali chlorides. 



Experiment 20 shows that acetic acid is also chlorinated in 

 the presence of lithium chloride, though much less readily than 

 benzene. 



It is evident from these results that the chlorination 

 observed in the experiments of Table I may have been largely, 

 or perhaps even wholly due to the secondary action of the dis- 

 solved chlorine always present in the liquid. The absence of 

 any apparent relation between current density and yield sup- 

 ports this view, and the higher yields obtained with platinum 

 electrodes may well be due to the presence of platinic chloride, 

 which would perhaps act as a chlorine carrier. In short, while 

 these experiments do not disprove, they certainly do not prove 

 the possibility of the electrolytic (anodic) chlorination of ben- 

 zine. Schleuderberg's results with benzene are equally incon- 



* See page 169. 



f Here, and in all subsequent references to acetic acid, the glacial acid is 

 to be understood. 



% J. Euss. Phys. Chem. Soc, xxii, 387 (Ber., xxiii, 546, R.). 



