505 



some time in tlio |)reseiu'c of an immense excess of alnniiniuin 

 chloride. 



A transformalion of cyclo-hexanc or of a mixture of benzene and 

 hydrogen into methylcyclo-peiitane at a high pressure and tempera- 

 ture has been observed, however by Ipatiew and Kizner. 



Ipatievv ') heated quantities of 40 grams of C,,Hi2 with 3 grams 

 of AljOj at 500 — 510^ and under a pressure of 70 atm. and could 

 liberate from a total of 700 grams a little of the cyclo-pentane 

 derivative ; in addition a great many aromatic compounds and 

 unsaturated hydrocarbons had formed. • 



Also this experiment does not say much more but that the hydro- 

 carbons are possible in presence of each other which, moreover, 

 does not signify much as, like in A soman's investigation, there is 

 here no question whatever of an equilibrium attained. Both experi- 

 ments prove that Al^Oj and AlCl^ are bad catalysts for the saturated 

 carbon-carbon bond, which could not be expected to be otherwise ^). 



Of much more importance is the observation that benzene is con- 

 verted into niethyicyclo-pentane when it is heated at 280° in a 

 sealed tube with an excess of HI '') because from this it follows 

 that at 280° and under pressure the cyclo-pentane derivative is more 

 stable than the cyclo-hexane or the mixture of ^\B.g and hydrogen. 



Of a pure catalysis there is. however, also no question in this 

 case as a very large excess of HI and I.^ has been employed here; 

 moreover, this superior action of iodine over AICI3 is in harmony 

 with the fact that the element can unite with hydrocarbons as well 

 as with hydrogen to form dissociable compounds under conditions 

 which are not far removed from that of the discussed transformation 

 (H. J. Prlns I.e.). 



In order to study the relation of the two isomers at the ordinary 

 pressure we will hax'e to choose in any case a C-C-activator such 

 as nickel exen if we run the risk that a part of the system attains 

 the methane equilibrium. 



The fact that not much methylcyclo-pentane can have formed in 

 the transformation of the cyclo-he.xene into benzene and cyclo- 

 hexane at 180° as studied by us, is, moreover, shown from the 



1) B. 44, 2987 (1911). 



-; On the other hand the large quanlilies of higher condensation products of 

 an aromatic character show that AICI3, in particular, activates the unsaturated 

 bonds. As soon as a saturated hydrocarbon begins lo lose hydrogen under tlie 

 influence of AIGI3 this property must lead to the actually observed complications. 



3) N. N. Kizner. Gent. Bl. 1897 II, 344. 



