Inverted Volcano Minimum Type Reactions

Inspection of Table 6.1 shows the following rule for inverted volcano type reactions  

Rule G4 A reaction exhibits inverted volcano (minimum rate) type behaviour when the kinetics are positive order in both the electron acceptor (A) and electron donor (D) reactant. 

In the context of Langmuir-Hinshelwood type kinetics, Rule G4 can be expressed as  

Three additional mles, also derived from experiment can be formulated  

Rule G5 The above rules G1-G4 apply also when D and A are both electron acceptors or electron donors. In this case D is always the stronger electron donor or weaker electron acceptor and A is always the weaker electron donor or stronger electron acceptor. 

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From Eq. (86), one can study the dependence of catalytic reactions on catalyst work function. Four types of rate-work function dependence have been identified experimentally, that is, electrophobic (3r/3 > 0), electrophilic (3r/3 < 0), volcano (where the rate exhibits a maximum with varying ) and inverted volcano type, where the rate exhibits a minimum with varying <1> (Fig. 52). 

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