Surface groups, interaction with protons

The MOH species which is present on the surface of the metal oxide is amphoteric in nature and has a tendency to attract both acidic and basic species. These active groups interact with either OH or groups of the analyte solution. These surface interactions lead to a protonation or deprotonation of the MOH groups and develop a surface charge which is equal to the pH of the analyte solution. The ion-sensitive CuO film thus contains surface sites which can specifically interact with H ions (hydrogenate) after interaction with an electrolyte solution. The CuO surface charge and surface potential depend on the protonation or deprotonation of these sites which is equal to the pH of electrolyte solution. 

ENDOR lines predicted by improved DFT calculations for methyl protons at 03(13 ) located at 16.5 MHz were broad and not observable due to incomplete averaging of the methyl proton couplings due to a hindering environment. Thus, the methyl groups at the C5(5 ) and C9(9 ) are located away from the surface of the pore and rapidly rotate, while those at 03(13 ) interact with the surface. Steric hindrance by the terminal bulky trimethyl cyclohexene rings preclude attainment of the requisite distance between Cu2+ and the C7=C8 and C8 =C7 bonds. 

Then, contrary to our previous hypothesis, the reaction proceeds via a Bai2 displacement of aniline on DMC. The product, mono-A -methyl aniline (PhNHMe), plausibly adsorbs into the zeohte in a different way with respect to anihne, because different H-bonds (N H — O-zeolite) take place with the solid. As recently reported by Su et al., A-methyl amines also may interact with NaY by H-bonding between the protons of the methyl group and the oxygen atoms of the zeolite this probably forces the molecule a bit far from the catalytic surface in a fashion less apt to meet DMC and react with it. This behavior can account for the mono-A-methyl selectivity observed, which is specific to the use of DMC in the presence of alkali metal exchanged faujasites in fact, the bis-A-methylation of primary aromatic amines occurs easily with conventional methylating agents (i.e., dimethyl sulfate). ... 

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