Homogeneous solution phase

Soluble support-based synthetic approaches offer the advantages of both homogeneous solution-phase chemistry (high reactivity, ease of analysis) and solid-phase synthesis (large excess of reagents, simple product isolation and purification) [98,99]. As a representative example, PEG, one of the most widely used soluble polymers, has good solubility in most organic solvents (i.e., dichloromethane, acetonitrile, dimethylformamide, and toluene), but it... 

Reaction scale-up using the Voyager system in genuine continuous-flow format is achieved by the use of special coiled flow-through cells. The reaction coils are made of glass or Teflon (Fig. 3.24) with a maximum flow rate of 20 mL min-1 and operational limits of 250 °C or 17 bar. The continuous-flow format should only be used for homogeneous solution-phase chemistry, as slurried mixtures may cause prob-... 

Oxidation by ozone is a homogeneous (solution-phase) reaction, so oxidation rates are readily estimated using Equation (23) and second-order rates constants from the literature (151-154, 159,160). Thus, for a typical concentration of ozone used in drinking water disinfection operations (10 5 M), and the appropriate k for, say, benzene (from 152), we can estimate... 

In addition to mesostructured aluminophosphates, mesoporous silica was also discovered to form natural shapes [41 14], It was found that quiescent, acidic, dilute and homogeneous solution phase conditions were the key ingredients for morphogenesis of curved shapes in the mesoporous silica system. Acidity, concentration and temperature of a synthesis mixture caused... 

In this section, we derive PDT expressions for activity coefficients and standard state chemical potentials that are conventional in physical chemistry and chemical engineering thermodynamics. We assume here a single homogeneous solution phase composed of several components, and write the following conventional expression for the chemical potential of component a in this multicomponent solution ... 

What we mean in this report by equilibrium and disequilibrium requires a brief discussion of definitions. Natural physicochemical systems contain gases, liquids and solids with interfaces forming the boundary between phases and with some solubility of the components from one phase in another depending on the chemical potential of each component. When equilibrium is reached by a heterogeneous system, the rate of transfer of any component between phases is equal in both directions across every interface. This definition demands that all solution reactions in the liquid phase be simultaneously in equilibrium with both gas and solid phases which make contact with that liquid. Homogeneous solution phase reactions, however, are commonly much faster than gas phase or solid phase reactions and faster than gas-liquid, gas-solid and... 

The formation of a sparingly soluble phase and its equilibrium with the solution is a more complicated process than equilibration reactions in a homogeneous solution phase. 

Preliminary to a second-generation synthesis of the 3-(9-methyl-y-( 1 -4)-mannans, Kishi and co-workers screened a series of mannosyl phosphates for the influence of the 0-2 protecting group and the anomeric stereochemistry of the donor on the outcome of the glycosylation reaction. As may be seen from Scheme 26, the use of benzyl ether protection under these homogeneous solution-phase conditions gave selectivities that were insufficient, whereas the 2-benzoates gave exquisite a-selectivity.34... 

Below the binodal, homogeneous solutions phase separate into a dilute supernatant of isolated globules and a concentrated sediment (assuming that the polymer has higher density than the solvent). The overall composition of the dilute phase of isolated globules is the lower volume fraction... 

There are numerous variations on free solution CE (FSCE), such as micellar electrokinetic capillary chromatography (MECC or MEKC), where a moving, pseudostationary phase is added to the CE buffer, and secondary chemical equilibria or interactions ensue that effect separations of even neutral compounds, as well as ionic analytes. However, in general, CE utilizes truly homogeneous, solution phase separation approaches, without a stationary (permanent, fixed) phase, making it perhaps ideally suited for molecular recognition in searching combinatorial libraries. 

The azo coupling between diazonium ions and coupling components is an important reaction for synthesizing dye compounds [29,30]. Usually, this reaction proceeds in a homogeneous solution phase. However, in certain cases, the reaction in a two-phase system is advantageous, as many coupling components are lipophilic, while diazonium... 

From both academic and industrial perspectives, the critical deficiency of ZN catalysts remains an inability to produce fundamentally different polyolefin materials of unique structure or composition, at will, by applying a set of experimentally derived and theoretically validated first principles for the de novo design of new generations of ZN catalysts. As is often the case with heterogeneous catalysts, such advances have first required the development of homogeneous, solution-phase catalytic systems which, in the present case, are based on molecularly well-characterized... 

We start by first analyzing the mechanism for this reaction as it may occur over the metal surface and then describe mechanistic aspects of how it proceeds over in the homogeneous solution phase on organometallic Pd clusters. 

Fluorous scavenging is carried out under homogeneous solution-phase conditions and is advantageous over polymer-bound scavenging. The quenching process is fast and does not require a large excess of scavengers. ... 

An integral enthalpy of solution, Ai/(sol), is the enthalpy change for a process in which a finite amount soi of solute is transferred from a pure solute phase to a specified amount of pure solvent to form a homogeneous solution phase with the same temperature and pressure as the initial state. Division by the amount transferred gives the molar integral enthalpy of solution which this book will denote by A//m(sol,mB), where me is the molality of the solution formed ... 

Hill and Cass have previously asserted that the important rate of electron transfer between GOx and, in their case ferrocene mediator, can be determined in homogeneous solution phase by the use of electrocatalytic currents obtained from die steady-state GOx-glucose reaction, and working curves derived by hticholson and Shain relating diffusion limited and catalytic currents.(7,S) A priori, this approach... 

At high temperatures and under conditions of intimate contact in the homogeneous solution phase, or for heterogeneous systems in which the reactants are suspended in a molten salt, reactions usually proceed extremely rapidly. 

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