124 PROCEEDINGS OP THE AMERICAN ACADEMY. 



according to Blau * parabromphenol, parabromanisol, aud a little 

 hydroquinone dimethylether. Blauf also fouud that symmetrical tri- 

 brombeiizol gave with sodic methylate at 130° symmetrical dibrom- 

 phenol and the corresponding anisol as principal products. These 

 results indicate that the atoms of bromine in these di-and tribromben- 

 zols exert some loosening effect, as monobrombenzol must be heated 

 to 200° before it reacts with sodic methylate ; j but all these actions 

 take place in sealed tubes, and even the maximum difference between 

 their temperatures of reaction and that of monobrombenzol is not very 

 great, only 70°. We decided therefore, in taking up this subject, to 

 try to obtain reactions in open vessels, that is, under conditions which 

 would have prevented all action with monobrombenzol, and to do this 

 it was obvious that we must increase the number of the atoms of 

 halogen which are to produce the loosening effect. We selected for 

 our first experiment accordingly the tribromiodbenzol having the 

 constitution Br.H. Br.I.Br.H, as in this compound we have iodine 

 as the element to be removed, and this is usually less strongly at- 

 tached to the ring than bromine or chlorine, and the three atoms of 

 bromine which are to produce the loosening effect are in the most 

 favorable positions for this purpose (two ortho and one para). Tri- 

 chloriodbenzol would probably have been even better, because chlo- 

 rine is more negative than bromine, but we preferred the bromine 

 compound on account of the great difficulty of preparing the trichlor- 

 aniline in quantity. 



Upon trying a variety of reagents with the unsymmetrical tribrom- 

 iodbenzol, we obtained negative results with all except two, sodic 

 ethylate and sodic methylate. Tliese converted it into symmetrical 

 tribrombenzol, melting point 119°, by replacing the iodine with hydro- 

 gen, the sodic etliylate acting to some extent even in the cold, more 

 freely when the solution in alcohoi and benzol was boiled under a 

 return condenser, while the sodic methylate did not act in tlie cold, 

 and only to a limited extent boiling. The unsymmetrical tetrabrom- 

 benzol Br. ILBr.Br.Br.H, which differs from the preceding compound 

 only in having an atom of bromine in place of the iodine, was also 

 partially converted into symmetrical tribrombenzol by boiling with 

 sodic ethylate, but there was much less action than with the iodine 

 compound, the tetrabrombenzol undergoing about as much substitution 

 when the solution was boiling, as was the case with the tribromiodbenzol 

 in the cold. The tribromchlorbenzol Br.H.Br.Cl.Br.H, on the other 



* Monatsli. f. Chem., VII. 627. t Ibid., 630. | Ibid., 636. 



