108 REPORTS ON THE STATE OF SCIENCE. 
If this hydrocarbon has the constitution represented by formula XV., then 
on treatment with bromine it would give rise to 3: 4-dibromo-l : 1-di- 
methylhexahydrobenzene (XVI.), which, on treatment with a reagent 
CH,.CH =CH 
Joe a CH—C ~y 
CMe; CHBr > CMe, CH 
*\cH, — CH,/ \cu, . cHY 
(XVL) (XVIL.) 
capable of removing the elements of hydrogen bromide, should yield 
1 ; 1-dimethyl-***-dihydrobenzene (XVII.).! But though the hydrocarbon 
obtained by the action of quinoline on the dibromodimethylhexahydro- 
benzene had the odour and gave the colour reaction characteristic of 
1 ; 1-dimethyl-A’**-dihydrobenzene, it has been proved by analysis and 
a study of its oxidation products to be an undoubted mixture of dimethy]l- 
dihydro- and dimethyltetrahydro-benzenes. 
Being under the misapprehension that the dibromodimethylhexahydro- 
benzene, from which the mixture of hydrocarbons had been prepared, 
was a homogeneous substance, the oxidation products expected were 
as-dimethylsuccinic acid, resulting from the oxidation of the dimethyldi- 
hydrobenzene, and /3)3-dimethyladipic acid, from the oxidation of the 
dimethyltetrahydrobenzene. 
CH,—CH 
CMe,< Ncupr > OMe Ncu > 
on cr.” \cH,. CH,” 
OH,. CO,H 
CMe 
CH,. CH, . CO,H. 
Instead there were actually obtained ua-dimethyladipic and as- 
dimethylsuccinic acids. This at once proved that the tetrahydrobenzene 
contained in the mixture of hydrocarbons must have been 1 : 1-dimethyl- 
A’-tetrahydrobenzene, and therefore that the supposed 1 : 1-dimethy]l- 
A*-tetrahydrobenzene, which formed the starting point of this investiga- 
tion, was not a homogeneous substance, but consisted of a mixture 
of 1 : 1-dimethyl-A?-tetrahydrobenzene and 1 : 1-dimethyl-A?-tetrahydro- 
benzene. If this were so, then on oxidation a mixture of aa- and 
PB-dimethyladipic acids would be obtained, and, as it had been found 
CH, . CO,H 
: +> OMe 
\GH,. CH,% “\cH,. CH, . CO,H 
CO,H 
CMe SoH, Z CMe 
CH,. CH, OH,. CH. CH,. CO,H. 
Q° 
possible, contrary to the statement of Blanc,” to separate these two acids,® 
a further quantity of 20 grams of dimethyltetrahydrobenzene‘ was pre- 
pared and oxidised with potassium permanganate.? There was uo diffi- 
culty in proving that the solid product obtained consisted of a mixture of 
aa- and /33-dimethyladipic acids, in which the latter largely predominated, 
thus proving definitely the correctness of the above inference regarding 
the composition of the substance previously described as 1 : ]-dimethyl- 
A3-tetrahydrobenzene. 
1 J.C.S., 1902, 81, 832. * Bull. Soe. chim., 1905 [iii], 33, 889. 
% Crossley and Renouf, J.C.S., 1906, 89, 1552. 
4 Tbid., 1905, 87, 1499. 5 Thid., p, 1502. 
