Condensed-phase chemistry

Wang Y A and Carter E A 2000 Orbital-free kinetic-energy density functional theory Theoretical Methods in Condensed Phase Chemistry (Progress in Theoretical Chemistry and Physics Series) ed S D Schwartz (Boston Kluwer) pp 117-84... 

Chemical reaction dynamics is an attempt to understand chemical reactions at tire level of individual quantum states. Much work has been done on isolated molecules in molecular beams, but it is unlikely tliat tliis infonnation can be used to understand condensed phase chemistry at tire same level [8]. In a batli, tire reacting solute s potential energy surface is altered by botli dynamic and static effects. The static effect is characterized by a potential of mean force. The dynamical effects are characterized by tire force-correlation fimction or tire frequency-dependent friction [8]. 

Atmospheric particulates (sea salt, carbonaceous soot, and sulfuric acid aerosols) are known to provide a condensed phase for conq>lex heterogeneous chemistry to occur. Although the presence of atmospheric particulates are known to alter trace gas concentrations, details of the specific chemical mechanisms for condensed phase chemistry have not been identified. 

Wang, A., Carter, E.A., In Theoretical Methods in Condensed Phase Chemistry, Schwartz, S.D. (ed.), Dordrecht Kluwer, 2000, pp. 117-184. 

As already mentioned, the experimental studies were restricted to singly charged ions. While singly charged ions are involved in the majority of the important condensed-phase ion chemistry, there are many important processes involving multiply charged ions. Thus, doubly charged ions such as Mg2+, Ca2+, Fe2+, Co2+, Ni2+, Cu2+, etc. are of paramount importance in condensed-phase chemistry and biochemistry. 

In this regard, it should be noted at this point that one of the products identified by CGC/MS from these pyrolysis reactions was SbBr3- Furthermore, the data presented concerning the importance of the polymer substrate in the degradation of the DBDPO and the proposed chain radical transfer mechanism [7] would suggest that the condensed phase chemistry could be much more important in antimony oxide/organohalogen flame retardant systems than had been previously thought. 

There has been tremendous progress in the development and practical implementation of useful continuum solvation models in the last five years. These techniques are now poised to allow quantum chemistry to have the same revolutionary impact on condensed-phase chemistry as the last 25 years have witnessed for gas-phase chemistry. 

In chapter 1, Profs. Cramer and Truhlar provide an overview of the current status of continuum models of solvation. They examine available continuum models and computational techniques implementing such models for both electrostatic and non-electrostatic components of the free energy of solvation. They then consider a number of case studies with particular focus on the prediction of heterocyclic tautomeric equilibria. In the discussion of the latter they focus attention on the subtleties of actual chemical systems and some of the danger in applying continuum models uncritically. They hope the reader will emerge with a balanced appreciation of the power and limitations of these methods. In the last section they offer a brief overview of methods to extend continuum solvation modeling to account for dynamic effects in spectroscopy and kinetics. Their conclusion is that there has been tremendous progress in the development and practical implementation of useful continuum models in the last five years. These techniques are now poised to allow quantum chemistry to have the same revolutionary impact on condensed-phase chemistry as the last 25 years have witnessed for gas-phase chemistry. 

The pristine environment of the gas phase can give some surprising reactions, viewed from the perspective of condensed-phase chemistry (2). Silver nitrate dissolved in acetonitrile added to a solution of benzenethiol in acetonitrile gives an immediate white precipitate and a brown gas is given off. The insoluble polymeric layered silver thiolate (3) is formed as the solvent abstracts a proton forming nitric acid the acid attacks the solvent. 

S.D. Schwartz (ed). Theoretical Methods in Condensed Phase Chemistry, 69-90, 2000 Kluwer Academic Publishers. Printed in the Netherlands. 

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