Kinetics of formation

Studies on the kinetics of formation of S2F2Q and reviews of appHcable Hterature have been reported (124—126). Other work has concentrated on the use of cell culture evaluation methods for assessing cytotoxic activity of SF decomposition products (127,128). Several laboratories seek to provide methods for accurately determining S2F2Q in operating electrical units (57). 

AH gg = —43.03 kJ/mol ( — 10.28 kcal/mol) including heat of solution, at standard state m = V) and may require a heat sink to prevent boiling of the reaction mixture. A 30% by weight suspension of MgO in 20°C water boils in the absence of any heat sink. The time to reach boiling is dependent on the reactivity of the MgO raw material, and this time can be only several hours for the more reactive grades of MgO. Investigations of the kinetics of formation of magnesium hydroxide by hydration of MgO have been reported (79). 

The kinetics of formation and hydrolysis of /-C H OCl have been investigated (262). The chemistry of alkyl hypochlorites, /-C H OCl in particular, has been extensively explored (247). /-Butyl hypochlorite reacts with a variety of olefins via a photoinduced radical chain process to give good yields of aUyflc chlorides (263). Steroid alcohols can be oxidized and chlorinated with /-C H OCl to give good yields of ketosteroids and chlorosteroids (264) (see Steroids). /-Butyl hypochlorite is a more satisfactory reagent than HOCl for /V-chlorination of amines (265). Sulfides are oxidized in excellent yields to sulfoxides without concomitant formation of sulfones (266). 2-Amino-1, 4-quinones are rapidly chlorinated at room temperature chlorination occurs specifically at the position adjacent to the amino group (267). Anhydropenicillin is converted almost quantitatively to its 6-methoxy derivative by /-C H OCl in methanol (268). Reaction of unsaturated hydroperoxides with /-C H OCl provides monocyclic and bicycHc chloroalkyl 1,2-dioxolanes. 

In the kinetics of formation of carbides by reaction of the metal widr CH4, the diffusion equation is solved for the general case where carbon is dissolved into tire metal forming a solid solution, until the concentration at the surface reaches saturation, when a solid carbide phase begins to develop on the free surface. If tire carbide has a tirickness at a given instant and the diffusion coefficient of carbon is D in the metal and D in the carbide. Pick s 2nd law may be written in the form (Figure 8.1)... 

It was found that the region of formation of the chalcogenide halides depends on the pH, the solvent concentration, and the ratios of the initial components in the charge. Temperature and pressure have practically no influence on the phase formation in these systems (285). The use of bromine (283) and SeBr2 as the solvent leads to a different mechanism, having different kinetics of formation and different growth-forms of the crystals (285). 

The kinetics of formation of phosphonates by reaction of o-dinitrobenzene with phosphites have been examined. The energy of activation for the reaction increases as the nucleophilicity of the phosphite decreases, e.g. ethyl diphenylphosphinite 14kcalmol"S diethyl phenylphosphonite 16 kcalmol S and triethyl phosphite 21kcalmol . An intermediate of the type (61), formed by nucleophilic attack of the phosphite, was proposed. In (61) there is a particularly favourable electrostatic interaction. That p-dinitrobenzene is unreactive, is thought to stem from the fact that this compound cannot form an intermediate with such a stabilizing factor. 

Christian, T.J. et al.. Kinetics of formation of di-D-difructose dianhydrides dining thermal treatments of inulin, J. Agric. Food Chem., 48, 1823, 2000. 

Considerable attention has been directed to the formation of nitroarenes that may be formed by several mechanisms (a) initial reaction with hydroxyl radicals followed by reactions with nitrate radicals or NO2 and (b) direct reaction with nitrate radicals. The first is important for arenes in the troposphere, whereas the second is a thermal reaction that occurs during combustion of arenes. The kinetics of formation of nitroarenes by gas-phase reaction with N2O5 has been examined for naphthalene (Pitts et al. 1985a) and methylnaphthalenes (Zielinska et al. 1989) biphenyl (Atkinson et al. 1987b,c) acephenanthrylene (Zielinska et al. 1988) and for adsorbed pyrene (Pitts et al. 1985b). Both... 

R. L. Christiansen, V. Bansal, and E. D. Sloan, Jr. Avoiding hydrates in the petroleum industry Kinetics of formation. In Proceedings Volume, pages 383-393. SPE Tulsa Univ Centen Petrol Eng Symp (Tulsa, OK, 8/29-8/31), 1994. 

For a number of copolymers, whose kinetics of formation is described by nonideal models, the statistics of alternation of monomeric units in macromolecules cannot be characterized by a Markov chain however, it may be reduced to the extended Markov chain provided that units apart from their chemical nature... 

R =c-C4Hg) to give vinyl acetylenes. The kinetics of formation of... 

Davies, M. S. Thomas, D. S. Hegmans, A. Berners-Price, S. J. Qu,Y. Farrell, N. A Comparison of the kinetics of formation of 1,4-interstrand crosslinks by the trinuclear clinical agent BBR3464 Preassociation and evidence of conformational flexibility J. Am. Chem. Soc. submitted for publication. 

Polyether complexation. The kinetics of formation of polyether crown, cryptand and related complexes have received considerable attention. Since formation rates are often quite fast, techniques such as temperature-jump, ultrasonic resonance, and nmr have typically been used for such studies. 

An investigation of the kinetics of formation of the Li+ and Ca2+ complexes of cryptand 2.1.1 using stopped-flow calorimetry suggests that complexation occurs initially at one face of the cryptand such that the metal is only partially enclosed (to yield an exclusive complex). Then follows rearrangement of this species to yield the more stable product, containing the metal ion inside the cryptand (the inclusive product) (Liesegang, 1981). X-ray diffraction studies have indeed demonstrated that exclusive complexes are able to be isolated for systems in which the metal is too large to readily occupy the cryptand cavity (Lincoln et al., 1986). 

The kinetics of formation and dissociation of the Ca2+, Sr2+ and Ba2+ complexes of the mono- and di-benzo-substituted forms of 2.2.2, namely (214) and (285), have been studied in water (Bemtgen et al., 1984). The introduction of the benzene rings causes a progressive drop in the formation rates the dissociation rate for the Ca2+ complex remains almost constant while those for the Sr2+ and Ba2+ complexes increase. All complexes undergo first-order, proton-catalyzed dissociation with 0bs — kd + /ch[H+]. The relative degree of acid catalysis increases in the order Ba2+ < Sr2+ < Ca2+ for a given ligand. The ability of the cryptate to achieve a conformation which is accessible to proton attack appears to be inversely proportional to the size of the complexed metal cation in these cases. 

The nature of the nucleation site as well as the kinetics of formation and dissociation of the H-induced and stabilized platelets have yet to be experimentally studied in detail. However, their generation in float-zone (Johnson and Herring, 1988b) as well as Czochralski-grown (Fig. 8) silicon argues against the involvement of oxygen or carbon in platelet nucleation. 

In the oxidation of isopropyl alcohol, the kinetics of formation of hydrogen peroxide for [H202] = 0.7 mol L 1 is described by the equation [58]... 

A deeper insight into the operation of the oxygen-atom effect as well as a further assessment of its dependence on chain length is provided by an investigation of Illuminati et al., (1981) on the kinetics of formation of benzo-crown ethers (54a) and of the analogous non-cyclisation reaction (54b)... 

Kinetics of formation of the dinuclear iron(III) complex [(tpa)Fe (p-0)(p-urea)Fe(tpa)]s+ tpa = tris(2-pyridylmethyl)amine were investigated in relation to the suggestion that urease action in vivo involves an intermediate containing Ni (p - O H) (p -ur e a) Ni. The mechanism of formation of the di-iron species from [(tpa)(H20)Fe(p-0)Fe(0H)(tpa)]3+ is proposed to involve three reversible steps (350). Three kinetically distinct steps are also involved in the deposition of FeO(OH) in... 

Gypsum, 4 582-601 5 467, 785t 23 576 forms and composition, 4 583t hardness in various scales, 7 3t in Portland cement, 5 467 in Portland cement hydration, 5 477t thermal reduction of, 23 577 thermodynamics and kinetics of formation- decomposition, 4 586-588 Gypsum board, 4 600-601 Gypsum processes, obtaining sulfur from, 23 576-577... 

Terpyridine ligands are known to form mono- and Ins-complexes with a wide variety of transition metal ions [321]. The stability constants and the kinetics of formation of these different complexes strongly depend on the nature of the used metal ions [322], In this respect, Rum is known to form a very stable mono-complex with one terpyridine ligand, while Ru11 only forms a stable bzs-complex with two terpyridine ligands [323]. 

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