Competitive mechanism

The kinetics of the decomposition of the 4-chlorobenzenediazonium ion under strict exclusion of oxygen (< 5 ppb 02, Schwarz and Zollinger, 1981) are compatible with the CIDNP results, subject to the reservation mentioned already, namely that CIDNP as a probe does not necessarily give results for all pathways, whereas kinetic measurements are normally related to the sum of all competitive mechanisms. The first reaction observable with conventional kinetic methods is the formation of the (E )-diazoate (t1/2 ca. 200 min), but it is also first-order with respect to the diazonium ion concentration. 

In Ihe s) tems for decompositicni of multiple otganic add substrates, the decomposition of acetic add was inhibited by the presence of butyric add tfarough a competitive mechanism, and the decomposition rate was correlated well by a puely competitive inhibition model as given by the bellowing equation. 

KOBAYASHI Y, SUZUKI M, SATSU H, ARAI S, KARA Y, SUZUKI K, MIYAMOTO Y, SHIMIZU M (2000) Green tea polyphenols inhibit the sodiiun-dependent glucose transporter of intestinal epithelial cells by a competitive mechanism. JAgric Food Chem. 48 5618-23. 

The mechanism of the nucleophilic substitution of a-halogenosulphoxides depends on structural factors and the nature of a nucleophile and may occur according to two competitive mechanisms a direct 8 2 substitution and an elimination-addition process . Thus, chloromethyl and bromomethyl sulphoxides react with alkoxide and mercaptide anions via an 8, 2 mechanism to give the corresponding a-alkoxy and a-alkylthiomethyl sulphoxides 502, respectively (equation 305). Optically active a-alkoxymethyl and a-alkylthiomethyl sulphoxides can also be obtained in this way - . 

As expected, borylaminoborazines behave like 2,4,6-trialkylaminoborazines. Two competitive mechanisms occurred during the thermal condensation in vacuo the formation of direct B N bonds between two borazinic rings and the formation of three-atom bridges of the N B N type between two rings (scheme 16).53... 

Anaerobic Azo-dye is converted batchwise. Dye conversion was described in agreement with [41], Inhibition by oxygen was taken into account according to a non-competitive mechanism. 

The plot eepjod = f(eeaux) in an enantioselective reaction is a simple operation that can sometimes be very informative from both synthetic and mechanistic perspectives. This plot is now widely used in mechanistic discussions concerning enantioselective catalysis. However, some cautions are needed, since this approach has to be combined with additional studies in order to get firm conclusions. If linearity is observed, one cannot reach conclusions on the mechanism, since even with species involving several chiral auxiliaries one may remain linear, as in the ML2 model with g = 1 in Eq. (7.3). If there are deviations from linearity, this could be a piece of information on the mechanism, for example, aggregations at some level of the chemical system, or some competitive mechanisms. References 27, 44, and 68 are only three among many published examples. 

Meyer WL, Capshew CE, Johnson JH, Klusener AR, Lobo AP, McCarthy RN, rearrangement of a-btomocamphotic anhydride. 2. Competitive mechanism in the formation of lautolenic acid,Chem 42 527—534, 1977. 

The data have been interpreted in terms of two competitive mechanisms. One of them corresponds to a direct proton transfer along the dihydrogen bond W-H- H-Cl with the slow formation of [W3S4Cl3(dmpe)3]+ and H2. The pathway at high acid concentrations requires a second HCl molecule, forming a dihydrogen-bonded system ... 

There are three biochemical mechanisms of CYP inhibition competitive, mechanism-based, and metabolite-intermediate-complex (Fig. 5.3). Each type of inhibitor differs in the nature of CYP binding. Competitive inhibitors are reversibly bound and can be competed off of the docking site if another substrate of higher affinity is present at a higher concentration. Therefore,... 

The ability of the Y group to be eliminated results apparently from the superposition of two factors on the one hand, the specific leaving ability of the Y group, and on the other, the possibility of intramolecular interactions between the Y group and the phosphorus atom. Further, the EHa mechanism is favoured by low hydroxide ion concentration680,719, since it is first order with respect to hydroxide ion, whereas the competitive mechanisms or p] are second order. 

The inhibition of COX-1 and COX-2 does not follow a competitive mechanism like other nonsteroidal antiinflammatory drugs but rather is due to a covalent enzyme inhibition via acetylation. After absorption, acetylsalicylic acid is hydrolyzed to salicylate which itself still shows some COX inhibition. Both compounds are bound (80-90%) to plasma proteins. The plasma elimination half-life is about 15 min for acetylsalicylic acid and between 3 and 22 h for salicylate depending on the dose (Needs and Brooks, 1985). 

Various techniques for solubilization are discussed in other chapters in this book, and will not be considered individually here. When one particular technique does not give a satisfactory outcome, a combination of techniques should be considered. However, it is important to keep in mind that a combination of techniques may not always give a synergistic effect because of competitive mechanisms. 

It is interesting also to compare the results of the present experiment, which shows directly that a competitive mechanism occurs in the co-adsorption of NO and CO, with previous studies on several surfaces of the platinum group metals. On Pt(lll) and Pt(110), Lambert and Comrie (65) have inferred from thermal desorption data that gaseous CO displaces molecular NO from the surface and causes also a conversion between two thermal desorption states of molecular NO. Similarly, Campbell and White (55) report that adsorbed CO inhibits the oxidation of CO by NO at low temperature on polycrystalline Rh. They attribute this to the occupation of sites by CO which are required for NO adsorption and dissociation. Conrad et al. (66) have used UV-photoelectron spectroscopy to observe directly the displacement of molecular NO by gaseous CO from Pd(110) and polycrystalline Pd surfaces. Thus, it appears that adsorption of molecular CO and NO is competitive on these... 

At room temperature, well below Tg, a brittle failure is generally observed. The ductile behavior appears when yielding becomes a competitive mechanism of deformation. At high speeds the brittle stress is not too much affected but ductile-brittle transition to higher temperatures. 

De-excitation of a fluorophore occurs via different competitive mechanisms described in the Jablonski diagram. The global rate constant, which is the inverse of the fluorescence lifetime, can be considered equal to the sum of the different rates of the competitive mechanisms. Thus, one can write ... 

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