ON THE STUDY OF HyDRO-AJJOMATIC SUBSTANCES. 225 



tion, ammonia is evolved in both of the possible directions, giving rise to 

 a mixture of A^-'-dihydrobenzeue (XI) and A^ ■ ^-dihydrobenzene (XIl) 



/CH : CHv yCHj . CH(NHjK 



CH/ >CHj ^- CH,< >CH, -^ 



\CH : CIK \CHj . CHCNHj)/ 



(XI) (X) 



CIIj . CH*^ 

 (XII) 



and they therefore conclude that ' the (/ewi-dimetliyl group influences the 

 position taken up by the double bonds,' 



/CH„ . CH(NH..)\ /CH : CH. 



CMe./ ' ■ >CH.. -> CMe./ \CH„. 



\CHj.CH(NHj)/ \CH : CH-^ ' 



If this is so, why does it not influence the position of the double 

 bonds when hydrogen bromide is eliminated from dibromodimethyl- 

 hexahydrobenzene ? For this is a reaction strictly analogous to the 



/CH : CH. /CH, . CHBr 



CMe,< >CH, «- CMe„<^ >CH„ 



\CH : CH^^ ^CH, . CHBr/ ' 



/CH : CH\ 

 ^CH„. CH^ 



C.Me.< "^CH . 



reaction used by Harries and Antoni, and yet it takes place in both 

 ways, giving rise to a mixture of the two possible hydrocarbons in equal 

 amounts. The presence of the (7e»i-dimethyl group certainly does not 

 exercise any apparent influence in this case, nor in the position of the 

 double bond formed when 3-bromo-l : 1 -dimethylhexahydrobenzeue loses 

 the elements of hydrogen bromide.' 



Harries and Antoni state that 2 grams of their diraethyldihydro- 

 benzene gave, on treatment with a nitrating mixture, 06 gram of 

 trinitro-7n-xylene, which might be regarded as a proof that dimethyl- 

 dihydrobenzene (H and A) does not contain the £/em-dimethyl group, for 

 though many cases of the wandering of a methyl group in derivatives of 

 gieni-dimethyldihydroresorcin have been recorded,''^ no single instance has 

 been observed in which a methyl group has wandered into anything 

 but an ortho- position. Moreover, dimethyldihydrobenzene (C and B) 

 undoubtedly contains dimethyl - Ji''=' - dihydrobenzene, and under the 

 influence of a nitrating mixture it is this hydrocarbon which is converted 

 into the two possible trinitro-o-xylenes. 



Recent Work on Hydro-aromatic Substances. 



Iiydrocarbo7is. — Methylenecyclohexane (I) has been submitted to 

 detailed investigation by Faworsky and Borgmann,^ who conclude that 

 the hydrocarbons of this supposed constitution, previously described by 

 Sabatier, VVallach, and Zelinsky and Gutt, are in reality mixtures of 

 methylenecyclohexane and 1 : methyl- -'-tetrahydrobenzene (II). For 

 the preparation of the pure hydrocarbon cyclohexylcarbinol, obtained by 



' J.C.S., 1906, 89, incr.. 2 Ibid., 1904, 85, 264 ; 1906, 89. 875. 



" Ber., 1S07, 40, 4863. 



1908. Q 



