118 ILLINOIS STATE ACADEMY OF SCIENCE 



POSITIVE REACTIONS OF HALOGENS 

 ATTACHED TO CARBON 



Ben H. Nicolet, University of Chicago 



"When the halogen atoms of an organic halogen com- 

 pound can be removed by hydrolysis, they are usually re- 

 placed by hydroxyl, and appear in the solution as halide 

 ions. This is often expressed by calling these halogens 

 negative. In a number of cases, however, the hydrolysis 

 of halogen compounds takes a different course, resulting 

 in the replacement of halogen by hydrogen, and the ap- 

 pearance of the halogen liberated as HOX or an equiva- 

 lent form. This behavior is well described by calling 

 such halogens "positive". In neither case is there any 

 intention of implying that, in the original compound, 

 the halogen was necessarily either negative or positive 

 to a degree sufficient to produce measurable ionization 1 . 



In most, if not in all, of the cases in which the halogen 

 is attached to an amino or imino nitrogen, or to oxygen, 

 the halogen is positive; this has long been recognized, 

 and even made the basis of quantitative determinations 

 of such compounds. Positive halogen attached to carbon 

 has been recognized in certain aliphatic compounds 2 . 



In the aromatic series, a considerable number of the 

 iodo and bromo-compounds show evidence of containing 

 positive halogen, and it is in general possible to predict 

 which will show this behavior 3 . A striking example is 

 3-iodo-4-aminobenzoic acid, which, as observed by 

 Wheeler and Liddle 4 , undergoes the following reaction 

 when heated "for a few minutes" with hydrochloric acid. 



AWl /VH^ Ufa 



CO^H CO^H e-Qji 



1 Cf., for the use of this idea of polar valence in organic compounds, 

 Stieglitz, J. Am. Chem. Soc. U, 1293 (1922), and earlier papers; and Lewis, 

 Valence and the Structure of atoms and Molecules (1923), particularly pp. 

 83 and 132. 



2 Nef, Ann. 308, 329 (1899); Howell with Noyes, J. Am. Chem. Soc. h , 

 991 (1920) ; Macbeth find others, J. Chem. Soc. 119, 1356 (1921) ; 121. 892, 

 904, 1109, 1116, (1922). 



3 Nicolet, J. Am. Chem. Soc. iS, 2081 (1921). 

 4 Am. Chem. J. 1,2, 453 (1909). 



