Reactive trapping

The efficacy of RF in stabilizing small rings is well illustrated by the fact that the azete from trifluoro-l,2,3-triazine is considerably more reactive. Trapping experiments were unsuccessful and a polymer was isolated at room temperature. The dimer (41) forms an observable anion with CsF, which confirmed the endo structure [87CC1699 90JCS(P1)975, 90JCS(P1)983], In contrast, trifluoro-l,2,4,-triazine is resistant to vapor phase photoysis and flow pyrolysis [87JCS(P1) 1251]. 

Generating 6 from 6,6-dibromobicydo[3.1.0]hexane (35) with methyllithium in the presence of styrene, Moore and Moser [55] observed the first [2 + 2]-cycloaddi-tions of 6. Bottini et al. extended the variety of compounds able to trap 6 to 1,3-cyclo-hexadiene [54, 60], furan, 2-methyl furan, 1,3-cyclopentadiene and methyl-substituted 1,3-butadienes [54], In all these reactions, the dimer 38 of 6 is a byproduct or, as in the case of the less reactive trapping agents, even the main product. Hence it is advisable to use a reaction partner of 6, if it is a liquid, as the solvent. 

Although the kinetic rate and energy partitioning are qualitatively consistent with a pure ER process, other aspects of the experiments and most of the theory (see discussion below) imply that the abstraction is more properly described as a combination of ER and HA reactions. The large a for abstraction is inconsistent with theoretical studies of a pure ER process as this requires a direct hit of the incoming H(D) with the adsorbed D(H) [380,381]. There is also no way to reconcile formation of homonuclear products with a pure ER process. In addition, similar kinetic experiments on other metals, e.g., Ni(100) [146], Pt(lll) [147,382], etc., are not even in qualitative agreement with the simple ER rate law above. In those cases, it is necessary to develop more sophisticated HA kinetic mechanisms to describe the kinetics experiments [383-385]. The key parameter of these kinetic models is the ratio of reaction to non-reactive trapping, pr/ps. For pr/ p, = 1, the HA kinetics looks very much like the simple ER case, and this is the reason H(D) + D(H)/Cu(lll) has such simple kinetics. 

Design Parameters. In a diffusion denuder an airstream, in laminar flow, contacts a surface (e.g., the inner wall of a tube) coated with a sorptive or reactive trapping medium for the gaseous pollutant of interest. Fine particles, which have diffusion coefficients more than 4 orders of magnitude smaller than those for gases, penetrate the denuder with high efficiency. Forrest et al. (40) reported losses of 0.2-2.2% for particles between 0.3 and 0.6 xm and about 4-5% for 1- to 2- xm particles. 

The wealth of productive bond-forming processes that radiate from this one intermediate can make planning a synthesis route around alkynyliodonium/alkylidenecarbene chemistry a daunting prospect. The key to steering the alkylidenecarbene down a desired pathway involves exploiting proximity effects to juxtapose an appropriately reactive trap near the carbene terminus. These constraints in carbene reactivity... 

Among the reactive trapping agents, only D P-unsaturated esters and nitriles that reduced with potentials in the range of -2.7 to -2.9 V proved to be effective other alkenes whose redox potential fell outside the range of-2.7 to -2.9 V (vs. Ag/AgNOs) window were unreactive. 

Solvent attack by a radical is a trapping reaction. If a standard AB diffuses to a radius / of 5R. that is. v — 4R — 20 A. then the probability that escape lias occurred is 0.80 (equations 7.20 and 7.22). In the absence of more reactive traps than the solvent (lor typical alkyl radicals. 7 10 s 1). escape... 

Although some successful syntheses have been realized at relatively high temperatures with transient carbenoids and very reactive trapping reagents like carbonyl compounds and chlorotrimethylsilane, halocarbenoid chemistry is in general performed below — 80 °C with preformed carbenoids. 

Reactive Trapping of 3,3 -Dichiorobenzidine Decomposition Products in Poiyethyiene-Based... 

Tamaki Y, Furube A, Murai M, Kara K, Katoh R, Tachiya M (2006) Direct observation of reactive trapped holes in Ti02 undergoing photocatalytic oxidation of adsorbed alcohols evaluation of the reaction rates and yields. J Am Chan Soc 128(2) 416-417... 

---