Strangeness changing reactions

As far as the rate of reaction is concerned, the change of kinetic order with temperature, and the strange shape of the Arrhenius plot (Figure 16) indicate that the nature of the rate controlling processes changes with temperature. 

There is something strange about this nitrogen pentoxide reaction. The reaction is the best example of a first-order gas phase reaction that we have and yet, according to equation (1), two molecules of nitrogen pentoxide are involved. Why should this, then, not be a second order reaction If it is a second order reaction we should expect the specific reaction rate to change markedly with pressure and depend on collision frequency. The best answer is given as follows ... 

Notice that there is no change in pH—a proton is lost from carbon and gained on oxygen. The reaction is known as enolization as it is the conversion of a carbonyl compound into its enol. It is a strange reaction in which little happens. The product is almost the same as the starting... 

The lifetimes given above relate to positronium in vacuum. In the medium a new possibility of destruction appears the positron bound in Ps can annihilate with one of strange electrons having appropriate (opposite) spin orientation. The process is called pick-off and leads to two quantum annihilation. If the medium is paramagnetic, another process shortening the o-Ps lifetime is possible the interaction with magnetic moments can transform o-Ps into p-Ps, which decays almost immediately (conversion process). Both e and Ps can participate in chemical reactions with molecules of the medium changing the Ps formation probability... 

The deprotonation of M-H to give M and H+ is one quite common dissociation reaction in which the pair of electrons of the bond goes to the metal. The metal doesn t change its total electron count, and its oxidation state decreases by 2. It s strange to think of a deprotonation as causing a reduction of the metal. The conundrum arises because of the oddities of the language that is used to describe metal complexes. The oxidation state of a complex with a M-H bond is calculated as if the bond were polarized toward H (i.e., M+ 11 ). Thus, when metal hydrides are deprotonated, it seems as if the metal is gaining electrons (from the hydride) that it did not have previously. 

Only two experimental investigations have been carried out to study isotope effects in unimolecular reactions at low pressures. Weston has studied the tritium isotope effect in the isomerization of cyclopropane to propylene, while Gray and Pritchard have studied the individual rates of decomposition of octadeutero-cyclobutane and unlabeled cyclobutane. Few details of the work by Gray and Pritchard are available. The isotope effect does not appear to change much with pressure. Strangly enough these authors find that the reaction exhibits an inverse isotope effect with A (QHs)/ (QD8) = I... 

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