Some mechanisms of electrophilic and radical substitution reactions

This mechanism provides an explanation for the relative reactivities observed for different ferrocenes in that the ease of oxidation of the iron depends on the nature of the ring substituents. A similar mechanism is proposed for the cyanation of ferrocene by HCN in the presence of ferric chloride and tet ydrofuran. It is suggested that the ferric ion oxidizes the HCN to a CN radical and ferrocene to the ferrocenium cation which then react, viz.. 

Another example is the arylation of ferrocene by aryldiazonium salts for which the mechanism given below and overleaf has been proposed. Other intermediates such as [( r-C5H5)2Fe+—N2Ar] may be involved [326]. 

The above examples show that there is no mechanistic distinction between radical and cationic substitution reactions. 

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Some mechanisms of electrophilic and radical substitution reactions Electrophilic substitution reactions have been proposed to occur by a general reaction path in which the attacking electrophilic group interacts first with the iron atom [287]. 

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