Adsorption behavior and mechanism of perfluorinated compounds on various adsorbents--a review.

This review focuses on polymers with upper critical solution temperature (UCST) in water or electrolyte solution and provides a detailed survey of the yet few existing examples. A guide for synthetic chemists for the design of novel UCST polymers is presented and possible handles to tune the phase transition temperature, sharpness of transition, hysteresis, and effectiveness of phase separation are discussed. This review tries to answer the question why polymers with UCST remained largely underrepresented in academic as well as applied research and what requirements have to be fulfilled to make these polymers suitable for the development of smart materials with a positive thermoresponse.

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Polymers with Upper Critical Solution Temperature in Aqueous Solution

The thermodynamics of the hydrophobic effect, as measured primarily through the temperature dependence of solubility, is reviewed, and then a class of models that incorporate the basic mechanism of hydrophobicity is described. These models predict a quantitative relation between the free energy of hydrophobic hydration and the strength of the solvent-mediated attraction between pairs of solute molecules. It is remarked that the free energy of attraction being just of the order of the thermal energy kT may be important for the effective operation of the hydrophobic effect in proteins. Deviations from pairwise additivity of hydrophobic forces are also briefly discussed.

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The hydrophobic effect

Reviews Environmental Contamination and Toxicology

One may discover a stone tool by chance but it takes more than luck to make a car or cell phone. With the advance of nanoscience, the synthesis of increasingly sophisticated nanostructures demands a rational design and a systems approach. In this Review, we advocate the distinction between thermodynamically and kinetically controlled scenarios, that is, whether a product forms because it is the most stable state or because the pathway leading to it has the lowest energy barrier. Great endeavours have been made to describe the multiple concurrent processes in typical nanosynthesis phenomena, so that the mechanistic proposals in the literature are brought into a common framework for easy contrast and comparison.

Thermodynamics versus Kinetics in Nanosynthesis

The majority of introductory chemistry and organic chemistry textbooks state that oil and water don't mix because of enthalpic effects. These texts generally make the argument that the mixing process is endothermic, reasoning that the water-water hydrogen bonds that must be broken in order to accommodate the solute are much stronger than the subsequent solvent-solute dipole-induced dipole intermolecular forces that are formed. In fact, in most cases the mixing process is exothermic, so the immiscibility of the two liquids must be explained by a loss of entropy in the system. The widely accepted model explaining the hydrophobic effect invokes the formation of icelike clathrate hydrate "cages" around nonpolar solute molecules. Water molecules at the surface of these relatively rigid clathrate structures are strongly hydrogen-bonded to one another. The formation of these solvent "cages" explains why both Delta H and Delta S are negative for the solution process, and the endergonicity of solvation is thus due to entropy and not enthalpy. Authors should remove from their textbooks the incorrect enthalpic/hydrogen-bond explanation for the hydrophobic effect. Because aspects of the correct entropic/clathrate "cage" explanation lie beyond the scope of introductory or organic chemistry courses, it may be wisest to omit any detailed physical explanation of the "like dissolves like" phenomenon. If the overall format of the text permits, a brief discussion of solvation entropy effects might be included in the section dealing with the immiscibility of oil and water

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The Real Reason Why Oil and Water Don't Mix

https://jfallen.org/publications/pdf/Silverstein_1993_FEBS.pdf

Chloroplast thylakoid protein phosphatase reactions are redox‐independent and kinetically heterogeneous

Although it is generally true that thermodynamics do not influence kinetics, this is NOT the case for electron transfer reactions in solution. Marcus Theory explains why this is so, using straightforward physical chemical principles such as transition state theory, Arrhenius’ Law, and the Franck-Condon Principle. Here the background and applications of Marcus Theory are presented, with special emphasis given to biological redox reactions. Interesting conclusions that arise from the theory are also discussed. These include the nonlinear contribution of reorganization energy (λ) to the activation free energy (ΔG⧧), as well as the existence of a defined “normal range” of reaction cell potential (ΔE°): Only if ΔE° is within this range does a reaction of lower λ have a lower ΔG⧧; outside of this range, the lower-λ reaction will have the higher ΔG⧧.

Marcus Theory: Thermodynamics CAN Control the Kinetics of Electron Transfer Reactions

https://www.jfallen.org/publications/pdf/Silverstein_1993_BBA.pdf

Redox titration of multiple protein phosphorylations in pea chloroplast thylakoids

Since at least the 1960s, organic chemistry textbooks have featured pKa tables for organic acids that include values for H2O and H3O+ (15.74 and −1.74, respectively) that are thermodynamically and chemically indefensible. Here we trace this error back to Bronsted’s early contributions in the 1920s to the Bronsted–Lowry Theory of acids and bases. Organic chemists generally defend the use of these values by citing measurements of the equilibrium constant for the water + methoxide acid–base reaction that suggested that methanol (pKa = 15.54) is a stronger acid than water; from this, organic chemists have concluded that pKa of water must be 15.74 rather than 14.00. Here we discuss the problems that invalidate this conclusion, the most important being that it is based on the use of the pure liquid standard state (mole fraction = 1) that is quite different from the standard state for acidities determined in dilute solution (molality = 1). Using the latter standard state, the equilibrium constant for the water/m...

Todd P. Silverstein

Papers

The Real Reason Why Oil and Water Don't Mix

Chloroplast thylakoid protein phosphatase reactions are redox‐independent and kinetically heterogeneous

Marcus Theory: Thermodynamics CAN Control the Kinetics of Electron Transfer Reactions

Redox titration of multiple protein phosphorylations in pea chloroplast thylakoids

pKa Values in the Undergraduate Curriculum: What Is the Real pKa of Water?