ON THE STUDY OF HYDRO-AROMATIC SUBSTANCES. 135 
The Study of Hydro-aromatic Substances.—Report of the Com- 
mittee, consisting of Professor W. H. PERKIN (Chairman), 
Professor A. W. CrossuEy (Secretary), Dr. M. O. FORSTER, 
Dr. H. R. Le Sueur, and Dr. A. McKENzIE. 
1. Bromozylenols obtained from dimethyldihydroresorcin.1—During 
the past year work has been largely concerned with the transformation 
of certain hydro-aromatic substances into bromoxylenols. These con- 
versions were originally noticed? during the action of phosphorus 
pentabromide on dimethyldihydroresorcin, when the main initial pro- 
ducts are not bromoxylenols, but are hydro-aromatic in nature, the prin- 
cipal ones isolated being dibromo- and tribromodimethylcyclohexenones. 
As the original reaction is very complicated, it was decided to study 
the transformations using the pure above-mentioned cyclic ketones, and 
as a result of the work so far concluded it has been established that: 
(a) The action of heat on dibromodimethylcyclohexenone (I) gives 
rise to 5-bromo-o-3-xylenol (II) and 6-bromo-o-4-xylenol (ITT). 
C(CH,). 
CH, He see CH, 
CH, : Br SH co CH, 
a Br ~ 
Br OH oa Br OH 
II. Ill. 
In the first of these rearrangements a methyl group has wandered, 
as previously noted, from carbon atom 1 to carbon atom 2; but in the 
second case from carbon atom 1 to carbon atom 6. 
(b) The action of dilute alcoholic potassium hydroxide on dibromo- 
dimethyleyclohexenone gives rise to 5-bromo-o-3-xylenol and 
4: 5-dibromo-o-3-xylenol (V). 
(c) Tribromodimethyleyclohexenone (IV) gives, under the influence 
of heat or alcoholic potassium hydroxide, mainly 4: 5-dibromo-o-3- 
xylenol (V) and another bromoxylenol, which has not, so far, been 
characterised. 
C(CH;), CH, 
3 HC fe | CHBr CH, 
BrC \ a co Br OH 
C Br Br 
IV. V. 
The constitutions of 5-bromo-o-3-xylenol, 6-bromo-o-4-xylenol, and 
4: 5-dibromo-o-3-xylenol have been definitely established by synthetic 
methods.* 
2. Derivatives of isopropyldihydroresorcin.—The method for the 
preparation of isopropyldihydroresorcin * has been improved so as to 
yield 75 per cent. of the theoretical amount of the dihydroresorcin. 
1 Proc. C.8., 1912, 28, 332. 2 J.C.S., 1903, 83, 110. 8 J.C.8., 1913, 108. 
4 J.C.S., 1902, 81, 675. 
