260 REPORTS ON THE STATE OF SCIENCE. 



2. The Action of Phosphorus Pentachloride on Trimethyldihydro- 

 resorcin. — In the nature of the substances produced, this reaction ' re- 

 sembles closely that of phosphorus pentachloride on dimethyldihydro- 

 resorcin,'^ for two bodies are obtained, one hydro-aromatic, namely 3 : 5-di- 

 chloro-1 : 1 : ■2-trimet]iyldihydrobenzene (8), and the other aromatic, namely 

 3 : 5-dichloro-l : 2 : 6-trimethylbenzene (9). 



.CCCHj) = CCL yCCCHa) = CCK 



(8) (CH3), . C< )>CH (9) CH3 . C<( \CH 



\CH, CCl-^ ^C(CH3)-CC1'^ 



But whereas, in the case of dimethyldihydroresorcin about 75 per 

 cent, of the theoretical yield of the hydro-aromatic dichloride is formed 

 and only a very small proportion of the aromatic substance, with trimethyl- 

 dihydroresorcin the result is reversed, the principal product being dichloro- 

 trimethylbenzene. 



Dichlorotrimethyldihydrobenzene can be converted into dichlorotri- 

 methylbenzene under the influence of phosphorus pentachloride or bromine, 

 and it has been ascertained that during this conversion the wandering methyl 

 group passes into an ortho position, as has already been observed with 

 several derivatives of dimethyldihydroresorcin.^ This has been proved 

 by analogy, and by a study of the properties of the aromatic dichloride 

 and of the possibility of directly esterifying the dichlorobenzenetricarb- 

 oxylic acid (dichlorohemimellitic acid) obtained by oxidising dichloro- 

 trimethylbenzene with nitric acid in sealed tubes. 



Recent Work on Hydro-aromatic Substances. 

 By Professor A. W. Crossley. 



Hydrocarbons. — In a paper entitled 'Derivatives of Cyclohexene' 

 Brunei "* gives a resum6 of work already published, together with a 

 description of certain new derivatives. 



1 : 2-, 1 : 3-, and 1 : 4-dimethyltetrahydrobenzene3* have been obtained 

 by the action of zinc chloride on the hydroxydimethylhexahydrobenzenes 

 mentioned below. They give the corresponding hexahydrobenzenes 

 when treated with hydrogen in presence of reduced nickel. 



Alcohols. — 4-keto-l-methylhexahydrobenzene reacts energetically with 

 organomagnesium compounds ^ to form tertiary alcohols of the general 

 formula 



<CH3 — CHg^ 

 >C . OH . R 

 ch,-ch/ 



Alcohols in which R=CH3, C,U^, C3H7, C,H,,, CgH,;, CeH,, and 

 CgHj.CHj are described, and also the substituted tetrahydrobenzenes 

 obtained from them, generally by the dehydrating influence of zinc 

 chloride. An exception was noted in the case of magnesium isobutyl 

 bromide, which gives i-ise almost exclusively to butylene and hydroxy- 

 methylhexahydrobenzene. 



4-hydroxy-l : 2-dimethylhexahydrobenzene, 4-hydroxy-l : 3-dimethyl- 

 hexahydrobenzene, and 2-hydroxy-l : 4-dimethylhexahydrobenzene have 



' Crossley and Hills, J. C. S., 1906, 89. 



2 Crossley and Le Sueur, J. G. S., 190;J, 81, 826, 1533. 



' J. C. S., 1902, 81, 1534 ; 1904, 85, 264. 



* Ann. Chivi. Phtjs., 1905 [viii], B, 200. 



'jSabatier and Mailhe, Comj>t. Rend., 1905, 141, 20. 



« JUd., 1906, 142, 438. 



