138 Cellulose 



resembles the quinone chloride above described, but the re- 

 action with this halogen is relatively incomplete. After remov- 

 ing the brominated product by hydrolysis with alkaline solutions, 

 and again exposing to bromine water, further reaction of the 

 same kind ensues. Proceeding in this way the lignone con- 

 stituent is completely removed as alkali soluble derivatives, 

 and cellulose is isolated. 



If, on the other hand, the lignocellulose be dissolved in 

 the ZnCl 2 .HCl reagent (p. 9) and bromine added, the con- 

 ditions are more favourable for combination. On precipitating 

 by water, after standing some time, a brominated derivative is 

 obtained, containing 10*2 p.ct. Br (equivalent to 4-5 p.ct. Cl). 

 After standing 16 hours, during which period the cellulose 

 is largely hydrolysed to soluble derivatives, a brominated 

 derivative is obtained, containing 19-5 p.ct. Br (equivalent 

 to 8 p.ct. Cl). Even under these conditions, therefore, the 

 bromine is taken up in considerably less proportion than 

 the chlorine. When the lignone is completely isolated 

 from the cellulose, e.g. by digestion with alkalis at elevated 

 temperatures, it is then brominated in higher proportion. 

 Compounds C 17 H, 4 Br 4 O 6 , C 1<5 H 12 Br 4 O 5 , CsjH^gB^Oio have 

 been obtained from the non-cellulose of esparto, isolated from 

 the alkaline by-products of the papermaker's boiling or pulping 

 process (p. 209 ; J. Chem. Soc. 41, 94). 



(3) Iodine. The lignocelluloses absorb iodine from its 

 aqueous solution and are coloured a deep brown. The re- 

 action has been quantitatively investigated, showing that jute 

 takes up 12*5 p.ct from decinormal solution in potassium iodide, 

 but the proportion varies according to the concentration of 

 the solution and conditions of the digestion. When these are 

 kept uniform the proportion of the halogen absorbed is con- 

 stant. The resulting compound, however, is of a loose descrip- 

 tion, the iodine being easily removed by solvents. 



