Solution reactivity properties

Chemical relaxation methods can be used to determine mechanisms of reactions of ions at the mineral/water interface. In this paper, a review of chemical relaxation studies of adsorption/desorption kinetics of inorganic ions at the metal oxide/aqueous interface is presented. Plausible mechanisms based on the triple layer surface complexation model are discussed. Relaxation kinetic studies of the intercalation/ deintercalation of organic and inorganic ions in layered, cage-structured, and channel-structured minerals are also reviewed. In the intercalation studies, plausible mechanisms based on ion-exchange and adsorption/desorption reactions are presented steric and chemical properties of the solute and interlayered compounds are shown to influence the reaction rates. We also discuss the elementary reaction steps which are important in the stereoselective and reactive properties of interlayered compounds. 

As already stated, speciation is the characteristic distribution of various ionic and/or neutral species in an aqueous solution. Speciation calculation, allowing practical estimation of the reactive properties of an aqueous solution, acidity, redox state, the degree of saturation of the various solids, and so on, is carried out on a thermodynamic basis starting from the chemical composition of the solution of interest and using the reaction constants of the various equilibria of the type seen in equation 8.19. 

Since grafting stabilizes species that would be too reactive in solution (in general, by allowing for isolated sites), and supported species may present catalytic properties unknown to the molecular chemistry, a lack of data concerning d(0) metal complexes derived from Nb and Cr is astonishing. Hopefully, the knowledge accumulated so far will be an incentive to develop the surface organo-metallic chemistry of these elements as well as the surface chemistry of the rare earths. 

Clearly, the effect of the solvent on a chemical reaction is much larger than previously assumed. In solution, the behaviour of ions and molecules is dictated mainly by the solvent and only to a lesser extent by their intrinsic properties. This will be elaborated on in subsequent Sections. A comparison of gas-phase reactivities and solution reactivities is given in Section 5.2. 

Theoretical calculations share with gas-phase kinetic and thermodynamic measurements the common aim of the understanding of the intrinsic reactivity properties of heteroaromatic compounds. The purpose of this subsection is to consider the predictive value of theoretical methods insofar as ionic substitution reactions on simple heteroaromatics are concerned. The topic under discussion is inherently limited by the wide range of interest in the understanding of the principles of these processes in solution. It is exactly in this field that an appropriate amount of data concerning gas-phase structural and reactivity properties of heteroaromatic compounds is at present available from modern experimental techniques that can be tested against theoretical predictions. 

By this approach, a variety of tritiated positive ions have been generated under largely different experimental condition, i.e., from a dilute gas state to dense gases and to liquids. The reactivity properties of such ions toward organic substrates have been evaluated by an extension of the mechanistic and kinetic tools typical of classical solution-chemistry studies. 

On the other hand, five-membered heteroaromatic molecules are the model structures first employed for kinetic investigation of the reaction mechanism in gas-phase heteroaromatic substitutions. While comparison of the relevant kinetic data with most common ion-neutral body collision theories and with theoretical predictions appears quite promising, nevertheless, accurate modeling of intrinsic reactivity properties of heteroaromatic compounds demands a more complete research effort, mainly directed to comparing the kinetic behavior of heteroaromatic compounds toward electrophilic and nucleophilic species (83IJM225 84JOC764) in the gas phase and in solution. 

Transfer of Solution Reactivity Properties to Electrode Surfaces... 

Returning to the question posed in the title, it seems evident that solution reactivity properties can be transferred to an electrode surface but with certain caveats. From the results described here, individual Ru-bpy sites appear to retain their intrinsic redox characteristics and their ability to undergo facile electron transfer. In addition, some of the more complex chemical reactions known for Ru-bpy complexes, including ligand-based reactions like RuNO+RuNC - RuONOo, and oxidation of azide, also occur in the films. It is also notable that the catalytic abilities of the Ru -NC>2 or RuIV-o groups can be transferred to the electrode-polymer interface. 

---