Hydroxyl group coverage

Analysis of the surface coverage revealed an average of 0.4 ionic liquid fragments nm 2, corresponding to the involvement of approximately 35% of all the hydroxyl groups of the pre-treated silica gel. 

Amido alcohol functional groups increase the surface hydrophilicity and thereby reduce interactions with biological membranes or proteins. The amino alcohols chosen (HNR1R2, where Rj and R2 each have at least one hydroxyl group) must provide the best compromise between hydrophilic coverage and viscosity while retaining high solubility. 

The dehydration reactions initiated by eliminating a hydroxyl group from an enediol are discussed in the present article. The products (usually dicarbonyl compounds) of these eliminations are normally transient intermediates, and undergo further reaction. The final products formed are determined by the carbohydrate reacting, the conditions of reaction, and the character of the medium. Except for a Section on analytical methods (see p. 218), the subject matter is restricted to aqueous acids and bases. The presence of compounds other than the carbohydrate under study has only been considered where it has helped to elucidate the mechanism involved. The approach here is critical and interpretative, with emphasis on mechanism. An attempt has been made to demonstrate how similar reactions can logically lead to the various products from different carbohydrates a number of speculative mechanisms are proposed. It is hoped that this treatment will emphasize the broad functions of these reactions, an importance that is not fully recognized. No claim is made for a complete coverage of the literature instead, discussion of results in the articles that best illustrate the principles involved has been included. 

The relative coverage of the free hydroxyls as a function of temperature is equal to one minus the relative coverage of the bridged hydroxyl groups. 

Activation energies for the coverage of surface hydroxyl groups on silica gel... 

Boehm et al.2 29 utilized this reaction to evaluate the hydroxyl group concentration at the surface of Aerosil. They found a maximal hydroxyl coverage of 3.1 OH/nm2 for a pretreatment temperature of 450 K. In the same period, also Uytterhoeven,30 Elmer31 and Folman14 have investigated the reaction of silica with SOCl2. 

Inelastic scattering of neutrons yields neutron scattering spectra that measure the vibrational energy levels of the material under study. For example, the chemisorption of water on Raney nickel was shown by inelastic scattering both to produce hydroxyl groups and to chemisorb water molecules on the surface at less than monolayer coverages. 

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