19, 6 Cole: Dissociation of Hexaphenylethane 685 
Lewis’s nomenclature will be used in a few cases where it is 
desired to emphasize the supposed electron positions. 
The normal structure of hexaphenylethane is accordingly the 
following: 
H H H H 
e un Ph Ph be Me 
(6) \ (3’) li) lie) (97 \ (6) 
A. H—C Cc—C+—c=—cC 
\ eg ea ag 
Wor vie Ph Ph ve ie 
H H H H 
(All the phenyl groups have the same structure as those given 
in detail.) 
The three strongly negative phenyl groups attached to carbon 
atom (1) draw six of its shell electrons away from the kernel. 
Consequently the remaining two electrons, namely those shared 
by carbon atoms (1) and (2), are held very firmly by the kernel 
of (1). Similarly these two electrons are held very firmly by 
the kernel of carbon atom (2). It therefore follows from the 
Lewis-Langmuir theory of valence that hexaphenylethane can- 
not possibly dissociate without a rearrangement of one or more 
of the phenyl groups. This conclusion is thoroughly substan- 
tiated by the experimental evidence that dissociation of this and 
similar compounds does not occur without color. The chromo- 
_ phoric nature of the quinoid form of the benzene ring has long 
been established. The reason for the formation of a quinoid ring 
is generally that electrons are pulled toward two atoms connect- 
ed to para or ortho carbon atoms. In the case under discussion 
it is evident that the strong pull of electrons toward one atom 
attached to each ring [carbon atoms (1) and (2)] is sufficient 
under certain conditions to cause rearrangement and consequent 
dissociation. 
In nonionizing solvents such as benzene, rearrangement and 
dissociation occur symmetrically. One electron between C (3) 
and C (4) is pulled to a position between C (2) and C (38), 
resulting in a quinoid ring in which C (6) lacks one electron. 
The electrons shared between C (1) and C (2) are now no longer 
held firmly by C (2), which momentarily has nine electrons in 
its shell. Therefore C (1) and,C (2) separate symmetrically, 
each retaining one electron of the shared pair. A double bond 
