Decomposition three-step

Model based on the variation of the number of active" coordination sites at the catalyst surface. The growth of tubules during the decomposition of acetylene can be explained in three steps, which are the decomposition of acetylene, the initiation reaction and the propagation reaction. This is illustrated in Fig. 14 by the model of a (5,5) tubule growing on a catalyst particle ... 

The second pathway consists of three steps, but provides the same type of final decomposition products ... 

Correspondence factor analysis can be described in three steps. First, one applies a transformation to the data which involves one of the three types of closure that have been described in the previous section. This step also defines two vectors of weight coefficients, one for each of the two dual spaces. The second step comprises a generalization of the usual singular value decomposition (SVD) or eigenvalue decomposition (EVD) to the case of weighted metrics. In the third and last step, one constructs a biplot for the geometrical representation of the rows and columns in a low-dimensional space of latent vectors. 

A preferable, three-step, procedure for preparing anhydrous bis(2,4-pentanedionato)zinc, m.p. 127°, in good yields involves (1) the preparation of bis(2,4-pentanedionato)zinc hydrate from zinc sulfate heptahydrate and 2,4-pentanedione in aqueous solution in the absence of heat, (2) conversion of the bis(2,4-pentanedionato)zinc hydrate into a bis (2,4-pentanedionato) zinc-methanol adduct, and (3) decomposition of the methanol adduct. 

According to the literature the thermal decomposition of NaAlH occurs in a three-step reaction ... 

It is well established in the literature [67, 70, 85-89] that hydrogen desorbs from a pure, uncatalyzed LiAlH hydride in a three-step decomposition very similar to that of NaAlH, the first of which goes through the melting of LiAlH ... 

Six years later, the same authors reported an improved version of their earlier synthesis of ellipticine (228) (527) (Scheme 5.197) by using the l-(p-methoxybenzyl)-5,6-dihydropyridone (1197) as 3,4-pyridyne surrogate (702,703). Thus, the dimethyl-furoindole 544 was treated with the unsaturated lactam 1197 (prepared from 5-valerolactam in three steps) in the presence of trimethylsilyl triflate (TMSOTf) to afford the carbazole 1199 as a single product in 40% yield. The low yield is presumably a consequence of decomposition of the intermediate adduct 1198 during... 

Co-oxidation of indene and thiophenol in benzene solution is a free-radical chain reaction involving a three-step propagation cycle. Autocatalysis is associated with decomposition of the primary hydroperoxide product, but the system exhibits extreme sensitivity to catalysis by impurities, particularly iron. The powerful catalytic activity of N,N -di-sec-butyl-p-phenylenediamine is attributed on ESR evidence to the production of radicals, probably >NO-, and replacement of the three-step propagation by a faster four-step cycle involving R-, RCV, >NO, and RS- radicals. Added iron complexes produce various effects depending on their composition. Some cause a fast initial reaction followed by a strong retardation, then re-acceleration and final decay as reactants are consumed. Kinetic schemes that demonstrate this behavior but are not entirely satisfactory in detail are discussed. 

The thermochemical behaviour of G2 (figure 5) is in some aspects different from products synthesised with CTAB [5] (not shown graphically, but listed in table 3). Both have a rather simple mechanism of decomposition with three steps of mass losses and an overall mass loss between 53 and 55%. 

Processes are under development to manufacture methylene diphenyl diisocyanate (MDI) without using toxic and corrosive phosgene. The proposed process schemes usually consist of three steps alkoxycarbonylation of nitrobenzene or aniline with CO and an alcohol to alkyl plienylcarbamate, condensation of the carbamate, and then thermal decomposition of the resulting urethane to MDI. For example, the condensation of methyl N—phcnylcarbamate (MPC), and IICHO into methylene diphenyl diurethane (MDU) is carried out in the presence of an acid catalyst. 

Thermal Decomposition. Wattenburg (Ref 48) observed that NaNs must be heated to 250° before decompn starts and that formation of NajN is a necessary stage in the decompn of NaNj to Na and Na. According to Garner Marke (Ref 69) the decompn in a vac at 257-365° was similar to that of KN3, but the catalytic effect of Na vapor was small. Decompn followed an induction period and then occurred in two or three steps (Refs 89 108). Audubert (Refs 72 80) noted that intense UV radiation was emitted during slow thermal decompn of NaNj and KN, (Ref 71). In a closed system the nature of gas or its absence had no effect but in a moving current of gas UV radiation was more intense (Ref 76). Bonnemay (Ref 100) detd the effect of bases and neutral salts on decompn rate. Thermal decompn of NaN3 has been studied extensively by Yoffe (Ref 131) and by Jacobs Tompkins (Ref 139)... 

When one follows the reaction arrows in Figure 9.12 from the bottom upward, the following important information can be noted In an acidic water-containing solution 0,0-acetals are hydrolyzed to give carbonyl compounds and alcohols. Such a hydrolysis consists of seven elementary reactions. First, the hemiacetal A (Nu = OR3) and one equivalent of alcohol are produced from the 0,0-acetal and water in an exact reversal of the latter s formation reaction, i.e., through a proton-catalyzed SN1 substitution (in four steps). What follows is a three-step decomposition of this hemiacetal to the carbonyl compound and a second equivalent of the alcohol. 

Fig. 16.30. Pd(0)-catalyzed arytation of a copper acetytide at the beginning of a three-step synthesis of an ethynyt aromatic compound. Mechanistic details of the C,C coupling Step 1 formation of a complex between the catalytically active Pd(0) complex and the arylating agent. Step 2 oxidative addition of the arylating agent and formation of a Pd(II) complex with a cr-bonded aryl moiety. Step 3 formation of a Cu-acetylide. Step 4 trans-metalation the alkynyl-Pd compound is formed from the alkynyl-Cu compound via ligand exchange. Step 5 reductive elimination to form the -complex of the arylated alkyne. Step 6 decomposition of the complex into the coupling product and the unsaturated Pd(0) species, which reenters the catalytic cycle anew with step 1.

Radical Polymerization. Free radical polymerization consists of three steps, initiation, propagation, and termination or chain transfer. Initiation consists of two steps, decomposition of the initiator to form a radical species, followed by addition of the initiator to the first monomer unit. 

The proposed reaction mechanism will consist of three steps (1) eollisional aetivation, (2) eollisional deactivation, and (3) spontaneons decomposition of the aetivated moleeule. Thus... 

Mal tseva et al. investigated the decomposition of Ca(AlH4)2 by DTA experiments which showed several exothermic and endothermic reactions associated with hydrogen evolution [182]. From in situ X-ray diffraction studies and DSC analysis of solvent-free Ca(AlH4)2, it is evident that the decomposition proceeds in three steps (Eqs. (5.37)-(5.39)) [76] ... 

Addition polymerization involves three steps initiation, propagation, and termination. During initiation, either radicals (Figure 5.9) or ionic species are generated from the controlled decomposition of an initiator molecule. The reactive intermediates are then sequentially added to the C—C bonds of monomers to propagate the growing polymer chain. Free-radical polymerization is the most common method currently used to synthesize polymers from vinyl-based monomers. 

Comersion of olefins into ethylene ketals. Hunt and Rodchcaver have described a method for conversion of olefins into ethylene ketals. Three steps are involved I) solvomercuration, 2) transmetalation, and 3) decomposition of the organopalladium intermediate. 

The best fits for the one step and the three step formal reaction model are displayed in Figure 6. Formal reaction models with parallel reactions always yielded worse fits than equivalent models with series reactions. This confirms results fiom an investigation of Virhegyi et al. on the thermal decomposition of 4-methyl-D-glucurono-D-xylan... 

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