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Reaction mechanisms, searching

Such techniques mean that the chemical literature may be used more effectively, and that its use can be partially automated. Might this lead to a way of automating organic synthesis To make most molecules there are many strategies which may be successful. If each reaction of each strategy can be evaluated for similarity to a reaction recorded in the literature, it should be possible to develop a route to most molecules by mechanically searching the chemical literature, so that suitable precedent is found for every transformation. [Pg.53]

The present investigation was carried out in order to extend eel to other types of transition metal compounds including organo-metallics. In addition to the search for new systems the modification of a well-known eel was used to learn more about the reaction mechanism. [Pg.160]

When the reactivity functions are applied to 8 in Fig. 33, the two reactions most favored by the reactivity function lead back to 47 and 48. Both reactions are endothermic and thus unfavorable in the direction leading to 8. In synthesis design, endothermic retroreaetions should be preferred. Therefore, in searching for a synthesis of 8, the compounds 47 and 48 are attractive precursors based on considerations of electronic effects, favorable reaction mechanisms for the conversion of 47 or 48 to 8 can be established. Furthermore, these conversions are thermochemically favorable. [Pg.70]

One example of the application of in situ electrochemical epr concerns the study of the Kolbe reaction. As was discussed in section 1.3, the Kolbe reaction involves some extremely complex processes and considerable effort has been expended in the search for the identities of the radical intermediates. Evidence for such intermediates remains sparse but one system that has provided such evidence is the electro-oxidation of triphenyl acetic acid (TPA) at a platinum electrode in acetonitrile (Waller and Compton, 1989). The case history of epr in the study of this system is a very good example of the application of the technique to provide details of a reaction mechanism. In... [Pg.200]

A good deal of this work had no impact in the development of models of molecular structure and the elucidation of reaction mechanisms one reason was Perrin s own coolness to quantum wave mechanics. 108 Another, according to Oxford s Harold Thompson, who studied with Nernst and Fritz Haber, was that researchers like Lecomte "did not know enough chemistry he was a physicist." 109 Perrin, too, approached physical chemistry as a physicist, not as a chemist. He had little real interest or knowledge of organic chemistry. But what made his radiation hypothesis attractive to many chemists was his concern with transition states and the search for a scheme of pathways defining chemical kinetics. [Pg.147]

In searching for the simplest mechanism to explain these observations and this rate form, Michaelis and Menten (1913) came up with the two-step elementary reaction mechanism... [Pg.613]

In all above mentioned applications, the surface properties of group IIIA elements based solids are of primary importance in governing the thermodynamics of the adsorption, reaction, and desorption steps, which represent the core of a catalytic process. The method often used to clarify the mechanism of catalytic action is to search for correlations between the catalyst activity and selectivity and some other properties of its surface as, for instance, surface composition and surface acidity and basicity [58-60]. Also, since contact catalysis involves the adsorption of at least one of the reactants as a step of the reaction mechanism, the correlation of quantities related to the reactant chemisorption with the catalytic activity is necessary. The magnitude of the bonds between reactants and catalysts is obviously a relevant parameter. It has been quantitatively confirmed that only a fraction of the surface sites is active during catalysis, the more reactive sites being inhibited by strongly adsorbed species and the less reactive sites not allowing the formation of active species [61]. [Pg.202]

This also characterizes the very style of the experimental studies. Even until recently the hydrodynamic theory of the detonation velocity, which was excellently confirmed in experiments, created a sense of contentedness and did not inspire the search for the chemical reaction mechanism or investigation of the conditions at the detonation wave front. If our paper brings about new experimental studies which penetrate deeper into the essence of the phenomenon, then our task will have been accomplished. [Pg.445]

In the same publication, a method for the parallelization of TAP experiments was also indicated. It was stated that ...high-throughput transient kinetics carried out in addition to high-throughput catalyst synthesis and testing both accelerate the search for new catalytic materials and bring fundamental insights into reaction mechanisms. ... [Pg.118]

Industrial research in this area is devoted mainly to the synthesis of Pc or PcM (M = Cu, Ni, Fe, Al, etc.) starting from urea and phthalic anhydride (or its derivatives) as the most cheap precursors. A survey of the literature shows that most of the articles and patents (among them Refs. 40 49) in the phthalocyanine area during the last 15 years are devoted to searching for the optimal conditions for Pc or PcM (M = Cu, Fe, Al, etc.) preparation, as well as the study and applications of different phthalocyanine modifications [50-56], synthesis of various Pc-substituted derivatives [57 66], study of reaction mechanisms of Pc formation [9,10,18,19,29,30], and much more relevant information generalized in a recent book [67]. [Pg.390]

Progress in decoding the mechanism of cytochrome P-450, which catalyzes epoxidation and hydroxylation of various hydrocarbons, has stimulated the search for comparatively simple and effective iron porphyrin systems [20-24], The reaction mechanism of monooxygenation can be illustrated by the following diagram ... [Pg.235]

One may expect that future work on the electrochemistry of diamond should take two paths, namely, an extensive investigation (search for new processes and applications of the carbon allotropes in the electrochemical science and engineering) and intensive one (elucidation of the reaction mechanisms, revealing the effects of crystal structure and semiconductor properties on the electrochemical behavior of diamond and related materials). It is expected that better insight into these effects will result in the development of standard procedures for thin-film-electrodes growth, their characterization, and surface preparation. [Pg.263]

Empirical Rate Expression and Search for a Reaction Mechanism. Based on the steady state results, the initial rate expression can be represented as ... [Pg.273]

Application of pulse radiolysis to polymers and polymerization was motivated at first by the success of radiation-induced polymerization as a novel technique for polymer synthesis. It turned out that a variety of monomers could be polymerized by means of radiolysis, but only a little was known about the reaction mechanisms. Early studies were, therefore, devoted to searching for initiators of radiation-induced polymerization such as radicals, anions and cations derived from monomers or solvents. Transient absorption spectra of those reactive intermediates were assigned with the aid of matrix isolation technique. Thus the initiation mechanisms were successfully elucidated by this method. Propagating species also were searched for enthusiastically in some polymerization systems, but the results were rather negative, because of the low steady state concentration of the species of interest. [Pg.38]

In search of model systems for iron hydrogenases, Sellmann et al. (67) investigated the interaction of I e(hdt)2 2 with H+, H2, and H . Formation of H2 was observed in the reaction with H+. The reaction mechanism was proposed to follow a step-wise protonation, forming a thiol-hydride complex and H2 is proposed to form via heterolytic elimination from the metal hydride species (Scheme 6). Theoretical calculations suggest that concerted H2 elimination from a dithiol species is thermally forbidden (67). [Pg.284]


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