Chichibabin’s hydrocarbon

In connection with Chichibabin s hydrocarbon it is appropriate to mention that there is little or no resonance between states of different multiplicity.4 Thus the singlet-triplet transition represented by the covalent and diradical structures of the hydrocarbon is a true equilibrium and not an example of resonance. 

The addition product (II) is also called Chichibabin s hydrocarbon and should not be confused with Chichibabin s (diradical) hydrocarbon of formula I. 

We have already seen that triphenylmethyl radical reacts both with itself to form Chichibabin s hydrocarbon (formula II, not the diradical) and with halogens and oxygen. The reactions of the stable radical are important because of the expectation that radicals too unstable to isolate will betray their presence by giving similar products. 

Sodium amalgam rather than sodium is used in the preparation of triphenylmethyl from the halide the mercury prevents the formation of sodium triphenylmethyl and of Chichibabin s hydrocarbon. 

The type of reactivity shown by the formation of Chichibabin s hydrocarbon extends to the activation of substituents other than hydrogen as well. For example, molecular silver will not usually remove fluorine from organic compounds, not even from triphenylmethyl fluoride. Yet the radical parafluorophenyldiphenylmethyl reacts with molecular silver to give silver fluoride.88... 

The case of Chichibabin s hydrocarbon (CflH5)2-CC6H4—CeH4-C (C6H5)a is somewhat more complicated. This hydrocarbon is deeply coloured and readily reacts with oxygen and for these reasons the suggestion was made that it may exist in the form of the bi-radical XIX,... 

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