491) 



Chemistry. — ''IVu' sidhHUy of ri.c/o hi/droctii'hoiis in connection 

 with their coafiguration. The trdnsfoi-niatioa of ci/cio-he,vene 

 into benzene and ci/clo-he.vane." (Contribution to tlie knowledge 

 of catalytic phenomena). Hy Prof. J. Böksp:ken and K. H. A. 

 SiLLEvis. (Communicated by Prof. A. F. Holleman.) 



(Communicated in the meeting of October 25, 1913). 



1. When studying the stability of hydrocarbon compounds below 

 400*^ and in the presence of catalysts account must be taken of the 

 fact that under those circumstances there is only one real stable 

 equilibrium^) namely 



CH, > C (graphite) + 2H„ 



which, below 400°, is practically situated entirely at the methane 

 side. 



Hence, if this gas is generated from an arbitrary hydrocarbon, 

 this will be a proof that the catalyst employed is capable of causing 

 the real equilibrium under the conditions of the experiment. 



Experience has now taught that under the influence of definite 

 conditions, transformations may occur and equilibria be possible 

 without methane being evolved or carbon being separated. 



All these latter equilibria are metastable and the possibility of 

 their realization is closely connected with a judicious choice of con- 

 ditions and catalyst. In order to choose properly we must first ask 

 which catalysts are the most suitable for definite changes. ^) 



In the hydrocarbons we are dealing with three kinds of bonds: 

 the C-C-, the C-H-, and the H-H-bond. In order to attain the real 

 equilibrium the catalyst must be able to exert au action on all bonds 

 (to effect a dislocation)-) which is only possible when, under the 

 conditions of the catalysis, it does not unite to form stable compounds 

 with the elements or combinations thereof which are to be "activated". 



On the other hand they should be substances which, under some- 

 what modified conditions, can unite with carbon as well as with 

 hydrogen (H. J. Prins). ') 



1) M. Mayer and V. Altmayer. B 40, 2134 (1907) ; v. Wartenberg Z. ph. Uh. 

 61, 366 (1908) 63, 269 (1909). 



-) 1 refer to the dissertation from H. J. Prins, Delft 1912, wherein, supported 

 by the principle of reciprocity, lie has endeavoured to give an explanation of the 

 catalytic phenomena. 



8) Recueil 29, 86 (1910). 



