Selectivity kinetically-based

The reaction to form the palladium complex is similar to that reported for amine salts, although here, because a bidentate chelating ligand is used, no chlorine atoms are retained in the complex, and the system is easy to strip. Also, as both reactions involve initial ion pair extraction, fast kinetics are observed with 3-5 min contact time to reach equilibrium at ambient temperature. The extraction conditions can be easily adjusted in terms of acidity to suit any relative metal concentrations and, because the reagent is used in the protonated form, good selectivity over base metals, such as iron and copper,... 

When the metalation of 2-fluoropyridine (8) was carried out at lower temperatures (-60°C), aside from the product of addition 13, evidence for the DoM product 12 was obtained by a TMSC1 quench experiment (Scheme 4). Complete chemospecificity was achieved only with the more selective LDA base at -75°C. [81JOC4494,81JOM(215)139]. Whereas the soft character of n-BuLi favors nucleophilic reactivity, the hard LDA leads to preferential protophilic attack. The stronger kinetic basicity... 

There are two general classes of selectivity equilibrium-based and kinetically based. Both types depend on specific interactions of the analyte molecule with the selective layer. In addition, there is also physical selectivity based on the highly specific interaction of the molecule with the electrostatic and electromagnetic fields. The topic of selectivity is broad enough to deserve its own chapter. We examine issues pertaining to selectivity in Chapter 2. 

The bromination depicted in Figure 1.29 proceeds via an unsymmetrical allyl radical. This radical preferentially (80 20) reacts to yield the bromination product with the more highly substituted C=C double bond. As this reaction proceeds under kinetic control, the selectivity is based on product development control the more stable (since higher alkylated) alkene is formed more rapidly than the isomer. 

Adsorption. The adsorption properties for selected AlP0,-based molecular sieves are summarized in Table VIII. The adsorption data are arranged for each structure-type in order of increasing adsorbate size. The large pore structure-types (5, 36, 46) with pores defined by 12-rings of oxygen readily adsorb neopentane (kinetic dia. 0.62 nm>. The 5 and 46 structure-types have been... 

In general, this effect is sufficient to allow selective kinetic deprotonation of methyl ketones, that is, where the distinction is between Me and alkyl. In this example, unusually, MeLi is used as a base LDA was probably tried but perhaps gave poorer selectivity. The first choice for getting kinetic enolate formation should always be LDA. 

In this context the supramolecular crystalline [15-22] or hybrid materials [23-35] can be prepared and constitutionally self-sorted by using an irreversible kinetic process like crystallization or sol-gel polymerization. The self-selection is based on constitutional internal interactions of library components, resulting in the dynamic amplification of self-optimized architectures, during the phase change process. With all this in mind, the second part will be devoted to sol-gel resolution of dynamic molecular supramolecular libraries, emphasizing recent developments, especially as pursued in our laboratory. 

In considering the application of process kinetics to anaerobic system design, this paper describes (1) the kinetic model employed, (2) the microbiological and biochemical evidence used as the basis for selecting the process rate-limiting step, (3) available kinetic information for that step, and (4) an illustrative example of kinetic based process design. 

Biological solids retention time (Oc) has been suggested in this paper as the kinetic based parameter of choice for use in design and control of fiuidized culture continuous fiow biological processes. The value of Oc selected for design of the process, (Oc ), directly determines the volume of reactor needed for a conventional digester system and a given waste fiow (Q) since the value of Oc is equal to the hydraulic retention time (0). The relationship between Oc and the reactor volume for the system with recycle is more complex and involves consideration of the effects of solids recycle rate and recycle solids concentration. 

MDEA is preferred for selective H2S removal and lack of degradation from COS and CS2. The selectivity is based on the kinetic effect that H2S is absorbed more quickly than CO2. Solution rates are lower than for non-selective designs, reducing both investment and operating costs. MDEA also permits the use of carbon steel, where other amines might require the use of stainless steel. 

Selected kinetic data for the thermal decompositions of metal azides (based on Table 1 of Fox and Hutchinson [18])... 

Kinetic-based methods employing catalytic (especially enzymatic) reactions are inherently more selective than many comparable chemical equilibrium methods. For example, of the approximately sixty oxidizable sugars and their derivatives, only two OS-D-glucose and 2-deoxy-D-glucose) are enzymatically oxidized by glucose oxidase at a significant rate. The oxidation of all others, including the isomeric... 

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