JACKSON AND CALVERT. — DERIVATIVES OF BENZOL. 123 



VI. 



CONTRIBUTIONS FROIVI THE CHEMICAL LABORATORY OF 

 HARVARD COLLEGE. 



ON THE BEHAVIOR OF CERTAIN DERIVATIVES OF 

 BENZOL CONTAINING HALOGENS. 



By C. Loring Jacksox and Sidney Calvert. 



Presented May 9, 1894. ^ 



Introduction. 



It is a well known fact that in substituted aromatic compounds the 

 firmness with which atoms of haloijen are attached to the benzol ring: 

 is diminished bj the presence of nitro groups in certain positions, so 

 that these atoms can be replaced by reagents, which would have no 

 effect on them if the nitro groups had been absent. It has also been 

 shown that certain other negative radicals exert a similar loosening 

 effect : these are the two oxygen atoms in substituted quiuoues — 

 chloranil and bromanil are very reactive bodies — the hydroxyl groups 

 in phenols,* and especially in substituted resorcine,f and also probably 

 carboxyl.t The object of the research described in the present paper 

 was to determine whether such a loosening effect could be produced 

 by less negative radicals, and for this purpose we have taken up the 

 study of derivatives of benzol, in which the substituting radicals are 

 halogens only, so that both the radicals removed and those which 

 make the removal possible belong to this same class, and the latter 

 are distinctly less negative than any of those enumerated above. The 

 amount of work already done in this field is meagre. Balbiano § found 

 that paradibrombenzol was converted into parabromphenetol, brom- 

 benzol, and a little benzol, when it was heated to 190° with sodic 

 ethylate. The same substance with sodic methylate at 150° gave 



* Armstrong and Harrow, Journ. Cheni. Soc, 1886, p. 447. 

 t Jackson and Dunlap, Tliese Proceedings, XXIX. 228. 

 t Rahlis, Ann. Cliem., CXCVIIL 112. 

 § Gazz. Chim., XL 401. 



