460 
CHEMISTRY: GOMBERG AND SCHOEPFLE 
that these compounds are monomolecular to the extent of 15%, 80%, 
and 100%, respectively.^ From these results one might infer that the 
dissociation of the hexa-arylethane into free radicals is greatly favored 
by the complexity or the weight of the aryl groups, — the dissociation 
becoming apparently more manifest also in proportion to the number 
of such groups. But the hypothesis that the dissociation of the hexa- 
arylethanes is proportional to the complexity of the aryl groups becomes 
wholly untenable when one compares triphenylmethyl with phenyl- 
xanthyl, CeHsC <^ O , which is monomolecular to the extent of 
82%.9 Is the union of the two phenyl groups the paramount influ- 
ence in this case? If so, why should a substance constitutionally 
so closely related to the xanthyls as phenyl-biphenylene-methyl^ 
, be completely dimolecular?^<^ 
It is obvious that from the few facts known to us at present it is diffi- 
cult, if not wholly impossible, to formulate the relation between the 
complexity of the aryl groups in the hexa-arylethanes on the one hand 
and the tendency of these ethanes toward dissociation into free radicals 
on the other. 
The Problem of this Investigation. — In order to obtain some further 
knowledge as to the factors governing the equilibrium between the di- 
and the mono-molecular phases of triarylmethyls, we decided to select 
for our study a related set of compounds. The following triarylmethyls 
were prepared for this purpose: 
1. (C6H5)3C Triphenylmethyl. 
2. (CeHs) 2C • C10H7 a-Naphthyl-diphenyhnethyl. 
✓C6H4> 
3. CsHs . C<' yO Phenyl-xanthyl. 
<C6H4V 
/'-Tolyl-xanthyl. 
<C6H4V 
/>-Chlorphenyl-xanthyl. 
C6H4/ 
