Catalytic simplified reaction scheme

Scheme6.13.1 Simplified reaction scheme of catalytic o-xylene oxidation to phthalic acid anhydride. [A more complex network with o-tolualdehyde and phthalide anhydride as intermediates is proposed by Calderbank, Chandrasekharan, and Fumagalli (1977), Anastasov (2002,2003) and Fiebig and Kuchling (2009)].

Fig. 7 Simplified reaction scheme for the catalytic oxidation of butene on a catalyst...

Sharma et al. (2005) developed a ID two-phase model for the analysis of periodic NOx storage and reduction by C3H6 in a catalytic monolith, based on a simplified kinetic scheme. They focused on the evaluation of temperature and reaction fronts along the monolith and their effect on NOx conversion. Kim et al. (2003) proposed a phenomenological control-oriented lean NOx trap model. 

Unlike the case of catalytic mechanism discussed in the previous section, the theoretical study of CE and EC mechanisms (see reaction scheme 4.IVb, c) in double potential pulse techniques is much more complex than that corresponding to a single potential pulse since the surface concentrations of the species involved in these reaction schemes corresponding to the application of the first potential pulse are time dependent (see also Sects. 3.4.2 and 3.4.3). Due to this, only simplified situations of these mechanism are considered in this section under planar diffusion conditions. The treatment of both mechanisms at other geometries can be found in [76-79]. 

A plausible, simplified mechanism for these catalytic oxidations includes two catalytic redox cycles (Scheme 4.61). The reaction starts with the initial oxidation of Phi to PhIO and then to PhI02 by the Oxone/Ru(III,V) system. The in situ generated highly active monomeric PhI02 species is responsible for the actual oxidation of organic substrates by known mechanisms [98,99],... 

Hydrogen peroxide catalyses the reaction between [Cr(H20)6] and edta and the Cr i-edta complex accelerates the decomposition of the substrate. In the absence of edta, the analysis of the kinetic trace suggests that Cr v and/or Cr are catalysts for the decomposition reaction in acidic media. The rate of oxygen evolution decreases markedly in the presence of edta, suggesting that the complexes are less active catalysts for the decomposition process. Any catalytic edta-containing species are considered as having chromium in an oxidation state greater than +3. A detailed reaction scheme for the redox process may be simplified to include the reactions (ox=oxidation, sub=substitution) ... 

Initial mechanistic analysis of the Strecker reaction catalyzed by a urea-based organocatalyst (Scheme 3.18) revealed that the catalytic activity is provided by the urea functionality of structurally complex catalyst 1. However, further studies revealed a bifunchonal character of urea and thiourea-based catalysts " as well as the possibility of multiple mechanistic pathways in catalysis of nucleophile-electrophile addition reactions. " Simplified but sufficiently effective (thio)urea catalysts 4a and 4b were used in the hydrocyanation reaction (Scheme 3.19) that was subjected to a combined experimental and computational study. °... 

Any heterogeneous catalytic reaction can be represented by a simplified scheme ... 

Involvement of trans-PtH2L2 in the catalytic cycle was confirmed by the wgs reaction, employing trans-PtH2L2 as the catalyst precursor, from which was also isolated trans-[PtH(C0)L]0H as its BPh salt. The following two processes (eq. 15,16) would complete the catalytic cycle. The formation of Pt3(C0)3L4 (v(C0) 1840,1770 enf ) in the reaction of PtH2L2 with CO is considered indirect evidence for the intermediacy of the coordinatively unsaturated Pt-(C0)L2. A simplified scheme of the cycle may then be depicted... 

Systematic investigations of the catalyst structure-enantioselectivity profile in the Mannich reaction [72] led to significantly simplified thiourea catalyst 76 lacking both the Schiff base unit and the chiral diaminocyclohexane backbone (figure 6.14 Scheme 6.88). Yet, catalyst 76 displayed comparable catalytic activity (99% conv.) and enantioselectivity (94% ee) to the Schiff base catalyst 48 in the asymmetric Mannich reaction of N-Boc-protected aldimines (Schemes 6.49 and 6.88) [245]. This confirmed the enantioinductive function of the amino acid-thiourea side chain unit, which also appeared responsible for high enantioselectivities obtained with catalysts 72, 73, and 74, respectively, in the cyanosilylation of ketones (Schemes 6.84 and 6.85) [240, 242]. 

Scheme 2 Simplified catalytic cycle for palladium-catalyzed aerobic oxidation ( oxidase ) reactions...

This reaction is used in the production of hydrogen in several commercial processes. It is an example of a heterogeneous catalytic reaction, hut the principles derived from it are also applicable to homogeneous and enzymatic catalytic reactions. A simplified scheme fur the reaction is given as follows ... 

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