B.— CHEMISTRY. 



43 



in concentrated sulphuric acid. The shift in the absorption band towards 

 the longer wave-lengths on change of solvent is very marked. The 

 addition of a little (4 eq.) strong sulphuric acid to the alcoholic solution 

 makes no measurable difference in the absorption curve, and no sulphona- 

 tion takes place in that solution. On the other hand the ether undergoes 

 sulphonation in the concentrated sulphuric acid solution, the reaction 

 velocity being very slow indeed at 15° and rapid at 50°. 



Now the alcoholic solution of anisole is strongly fluorescent, the 

 emission band having the same frequencies as the absorption band B in 

 fig. 2, that is to say, the frequency of the fluorescence of the alcoholic 

 solution is the same as the frequency of the characteristic absorption band 

 of the sulphuric acid solution. The suggestion may at once be made that the 

 final activated state produced when the ether in alcoholic solution absorbs 

 its characteristic quantum h)^, is that activated state which enters into 



2.200 24 26 28 3,000 32 34 36 38 4,000 42 34 36 38 4,000 4 2 



WAVE -NUMBERS 

 Fig. 2. 



the sulphonic acid reaction. In other words, the irradiation of the alcoholic 

 solution, to which a little sulphuric acid has been added, by light of the 

 frequencies of the absorption band A should induce the formation of the 

 sulphonic acid. This was proved to be the case. The acidified alcoholic 

 solution of anisole was irradiated with the light from a quartz mercury 

 lamp for 96 hours, after which the solution was diluted with water and 

 neutralised with barium hydroxide. After filtration from the insoluble 

 barium sulphate, the solution was extracted with ether in order to remove 

 any unchanged anisole. None, however, was recovered. On evaporation 

 the barium salt of the sulphonic acid was obtained in approximately 

 quantitative yield and there was no evidence of the formation of ethyl- 

 sulphuric acid. 



In fig. 2 the curve C represents the absorption curve of the sulphuric 

 acid solution of anisole after it has been allowed to remain at 50° for a 



