Van Name and Maryott — Chlorination of Benzene. 167 



Table VI. 

 Chlorination in Acetic Acid Solution. 



Monochlorbenzene at 10'4° 

 Initial concentrations : C H CI, *147 

 LiCl, 1-76 



t 

 min. 





 180 

 540 



AgCl from 

 10 cc 



grm. 



•2178 



•2198 



•2223 



•2228 



•2295 



•2282 



mean 

 •2188 



•2226 



•2288 



Difference, 

 AgCl 

 grm. 



•0038 

 •0062 



p-Dichlorbenzene at 

 10-4° 



t 

 hours 



16 



AgCl from 

 10 cc 



grm. 

 •2337 

 •2341 

 •2321 

 •2315 

 •2325 

 •2333 



mean 

 •2339 



•2318 



•2329 



when calculated as above. Table YI also shows that under 

 similar conditions p-dichlorbenzene is not appreciably chlor- 

 inated. The rate of chlorination of benzene hexachloride was 

 not tested. 



We may now consider whether the results of Table Y give 

 any evidence of anodic chlorination. If the chlorination were 

 more rapid during the electrolytic periods it would tend to 

 increase the slope of those sections of the curves in fig. 2 

 which precede the crosses, and to decrease the slope of those 

 which follow them, thus forming peaks and hollows in regular 

 succession. The results do not confirm this, for the breaks in 

 the curves occur in a wholly unsystematic manner and are in 

 most cases too small in comparison with the errors of experi- 

 ment to have any weight as evidence of a disturbing effect. 

 It is, however, important to know how large the current yield 

 would have to be, under the conditions, to produce distinct 

 breaks in the direction of the curve. The magnitude of the 

 effect to be expected may be calculated as follows : In experi- 

 ment 4, period 2, for example, 0*4: ampere hour is equivalent 

 to '00746 mols of chlorine, which, assuming a 10 per cent 

 current yield, would convert '000746 mols of benzene into 

 monochlorbenzene. As the volume of liquid was here 300 cc , 

 this would decrease the benzene concentration by *0025 mols 

 per liter. The observed value of x at the end of this period 

 was *1339, the decrease due to the non-electrolytic reaction, 

 therefore, '1314. Similarly, at the end of period 4 (volume 

 230 cc ), the value of x corrected for a 10 per cent current yield 

 becomes *2434. If the velocity constants of experiment 4 are 

 now recalculated, using these corrected values of x for the 

 ends of periods 2 and 4, respectively (but not at the beginning 

 of 3 and 5), we obtain the figures given in Table YII, column 

 5, which represent, subject to the experimental error, the vary- 



