Propinquity effects order

Propagation of errors, 40, 48, 248 Propinquity effect, 263, 365 Protol5Tsis, 147, 148 Proton inventory technique, 302 Proton transfer, 166 direct, 148 extent of, 346 fast, 97, 146, 173 isotope effect in, 296 partial, 395 Proximity effect, 365 Pseudo-first-order rate constant, 23 Pseudo-first-order reaction, 61 Pseudo-order rate constant, 23 Pseudo-order reaction, 23 Pseudo-order technique, 26, 78 Pulse NMR, 170... 

The Sn2 mechanism is a second-order nucleophilic substitution whose rate depends on the concentrations of both the alkylating agent and the nucleophilic site. Busulphan 12.31), which is one of the few agents reacting by this mechanism, achieves this result by a propinquity effect without prior ionization, thus ... 

Amide hydrolysis is not only subject to acid and base catalysis, but may be also brought about by a neighbouring group in the amide, the so-called propinquity catalysis effect. Wolfrom et a/.238 were among the first to suggest this possibility, in order to explain the observed hydrolysis of aldonamides, viz. 

Propinquity (proximity) effects are important in reaction rate enhancement. In the case of the following compounds, anhydrides (products formed on removal of water) form at different rates. Arrange the compounds in order of their rates of anhydride formation and explain the reasons for the ordering. 

---