188 Proceedings of the Royal Irish Academy. 



2. Dibromide of JDianisyliciene-diacestoresorcinol dimethylether. 



This compound was the only product isolated in an attempt which was 

 made to prepare the corresponding tetrabromide. 



One gram of the dimethylether was dissolved in 10 c.cs. of chloroform, 

 and - 7 gram of bromine (four atoms) was added to the solution. The colour 

 of the bromine disappeared almost immediately, apparently without evolution 

 of hydrobromic acid. The colourless solid which separated after addition of 

 absolute alcohol was recrystallized several times from a mixture of chloroform 

 and alcohol. 



A determination of bromine in the compound by Stepanow's method gave 

 the following results : — 



- 2121 substance on treatment with sodium and alcohol 



gave an amount of sodium bromide which required 6 - 7 c.cs. of 



N 



r« AgN0 3 for complete precipitation 



corresponding to Br 25'2 

 CjsHisOeBri requires Br 41"1 

 C 26 H 26 6 Br, requires Br 25-8 

 C 28 H 21 6 Br 2 requires Br 25-95 



The bromine percentage 25 - S corresponds to the formula (VI . 



.CO . CH : CH . C 6 H 4 . OCH 3 

 (CH 3 0) 2 C 6 H< 



x CO . CHBr. . CHBr. . CeHj . OCH 3 



and the bromine percentage 2595 to the formula (VII). 



,CO . CBr : CH . C 6 H 4 . UCH 3 

 '\C0 . CBr : CH . C,H« . OCH 3 



(CH 3 0) 2 C 6 H 2 < 



It is probable that an unstable tetrabromide is first formed, and that in 

 the subsequent crystallizations it splits off two molecules of hydrobromic acid 

 forming the dibromide. A similar phenomenon, observed by Miss O'Neill 

 in the case of dipiperonylidene-diacetoresorcinol-dimethylether, will be 

 described later. 



The dibromide crystallizes from a mixture of chloroform and alcohol in 

 colourless needles, which melt at 166-168° C. It is almost insoluble in cold 

 alcohol, ether, or ligroin and sparingly soluble in chloroform. 



On heating the substance with concentrated hydriodic acid an almost 

 black resinous solid was obtained which did not crystallize. 



