Bases strong, proton-specific

Pathway b is the specific base catalyzed (HO -catalyzed) hydrolysis. This bimolecular 5n2 reaction leads to the alcohol and nitrate. A peculiar pathway is carbonyl elimination (Fig. 9.1,c). This bimolecular reaction is catalyzed by strong bases and produces a dismutation of the two moieties, the organic group being oxidized to a carbonyl compound and nitrate being reduced to nitrite. Note that proton-catalyzed hydrolysis does not appear in Fig. 9.1 since this mechanism either does not occur or is negligible. 

Nucleophilicity. A distinction is usually made between nucleophilicity and Lowry-Bronsted basicity [213]. The latter involves specifically reaction at a proton which is complexed to a Lewis base (usually H2O), while the former refers to reactivity at centers other than H. Linear correlations have been shown for gas-phase basicity (proton affinity) and nucleophilicity of nitrogen bases toward CH3I in solution [214] where the solvent is not strongly involved in charge dispersal. In each case, reaction of the base/nucleophile... 

Polymer electrolyte fuel cell (PEFC) is considered as one of the most promising power sources for futurist s hydrogen economy. As shown in Fig. 1, operation of a Nation-based PEFC is dictated by transport processes and electrochemical reactions at cat-alyst/polymer electrolyte interfaces and transport processes in the polymer electrolyte membrane (PEM), in the catalyst layers consisting of precious metal (Pt or Ru) catalysts on porous carbon support and polymer electrolyte clusters, in gas diffusion layers (GDLs), and in flow channels. Specifically, oxidants, fuel, and reaction products flow in channels of millimeter scale and diffuse in GDL with a structure of micrometer scale. Nation, a sulfonic acid tetrafluorethy-lene copolymer and the most commonly used polymer electrolyte, consists of nanoscale hydrophobic domains and proton conducting hydrophilic domains with a scale of 2-5 nm. The diffusivities of the reactants (02, H2, and methanol) and reaction products (water and C02) in Nation and proton conductivity of Nation strongly depend on the nanostructures and their responses to the presence of water. Polymer electrolyte clusters in the catalyst layers also play a critical... 

The difference between the most kinetically favoured cyclisations is easily seen in the type of base needed to cyclise chloro-alcohols to three- and five-membered cyclic ethers (epoxides and THFs). Chloroethanol 19 cyclises only as the oxyanion specific base is needed, i.e. a strong enough base to remove the OH proton completely. By contrast, 4-chlorobutanol cyclises by general base catalysis the proton is removed during the cyclisation 22 and weak bases will do.1, 2... 

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