Decomposition routes

Direct Meutra.liza.tion, Because of the avadabiHty of by-product ammonium salts, the double decomposition routes are usually more favorable economically for ammonium chloride manufacture. However, where surplus hydrogen chloride is available, the direct neutralisation process has been used (15)... 

This double decomposition route was developed in Germany and has been used in the UK since 1971. 

CH2CMe3, or -CH2SiMe3) often leads to stable complexes since this prevents at least one facile decomposition route namely y3-elimination. 

Thiophenols may also be synthesized via the photochemical decomposition route 156). Thus, treatment of arylthallium ditrifluoroacetates with an aqueous solution of potassium Ar,AT-dimethyldithiocarbamate led in quantitative yields to the formation of the corresponding aryl AT,A -dimethyl-dithiocarbamates. Subsequent photolysis in aqueous acetone then led to disulfides which were reduced to the thiophenols. A small amount of aryldithiocarbamate formed as a by-product in the photolysis was converted to the same thiophenol by hydrolysis. The overall reaction sequence is illustrated in Eq. (18). 

Figure 4.1 Synthetic scheme for production of iron-oxide NPs using a thermal-decomposition route. From reference [32] with permission.

A large number of NHC complexes tolerate moisture, air, and elevated temperatures [1, 2]. The stability of these compounds is, however, still limited. One of the most important decomposition route for these complexes is the reductive elimination of 2-aIkyl or 2-aryl substituted azolium salts from NHC complexes with alkyl or aryl groups in cA-position to the NHC ligand. This route can be considered as the reverse reaction of the previously discussed oxidative addition of C2-X bonds to transition metals and has been reviewed [94, 123]. 

The major difference between copper and other transition metals is the CO2 selectivity. Several investigations [120, 123, 124] showed that CO concentrations up to 25% could be achieved during CSRM, a result comparable to the decomposition route. The influence of the support was demonstrated to be significant. The high CO concentrations obtained for these transition metals make them highly unsuitable for fuel cell applications. 

Since dithio- and selenocarbamates and their derivatives are used so widely in the deposition of thin films and nanoparticles that a mechanistic study of their decomposition behavior was carried out by O Brien et al. [ 107]. Wold et al. [78] studied the decomposition products of Zn(S2CNEt2)2 using gas-chromatography mass spectrometry (GC-MS) and their reported deposition path shows clean ehmination of ZnS from the precursor (Eqs. 1 and 2 below). However, the proposed decomposition route is somewhat different to the step-by-step fragmentation observed in the electron-ionization mass spectrometry (EI-MS) of the compoimd, (Eq. 3). This difference can be attributed to inherent differences between the two techniques. 

Methylquinoline radical cations (111) and (112) may involve azabenzotropylium (113) or pyridotropylium cations (114) in their decomposition routes (67JOC997), while McLafferty rearrangements are well represented, for example where three-carbon side chains (or longer) are present (67JOC997, B-71MS364), as shown for molecular ions (115), (116) and (117). 

Thiourea (SC(NH2)2), the sulphur analogue of urea, is the most commonly used sulphur precursor. There are a number of possible decomposition routes for thiourea in aqueons solntion (it is invariably nsed in alkaline solntions). Probably the most important is... 

Recently, the primary processes were investigated using pulse radiolysis with two extractant-alkane systems (182, 292). Transient optical absorption spectra proved that in the presence of ligands like TODGA, the excited species of -dodecane (singlet excited state and radical cation) disappeared immediately. Results showed that an energy transfer occurred from the excited alkane to the extractant molecule (TBP, TOPO, or amide), which constituted an additional decomposition route, as described in the following set of reactions ... 

The masked dendralenes 36 are crystalline compounds, stable at room temperature, from which, as hoped, the hydrocarbons 37 could be released on demand in good yields by high-temperature pyrolysis. No solvent is required in these cheletropic reactions which facilitates the work-up. The dendralenes 37 obtained, up to [8]dendralene, have been completely characterized by the usual spectroscopic and analytical methods and can, although they tend to polymerize, be handled under the usual laboratory conditions (see below). The sulfolene decomposition route has recently been applied to the synthesis of many other cross-conjugated compounds, among them the hydrocarbons 39-42 (Scheme 7) [12]. 

Ammonium perchlorate and ammonium dinitramide can decompose by similar routes, but perchlorate, in particular, has several other decomposition pathways available. One decomposition route of ADN produces ammonium nitrate andN20 [138],... 

The first question is which decomposition route is preferred, via formate or formyl,... 

H. BockandB. Solouki,Angew. Chem., 93,425 (1981) Angew. Chem., Int. Ed. Engl., 20,427 (1981), report on application of PE spectroscopy to determine thermal decomposition routes to detect unstable intermediates and to optimize heterogeneously catalyzed reactions (142... 

The fragmentation patterns of compounds (47a-d) have also been studied, with the loss of N2 being the primary decomposition route of both doubly and singly charged molecular ions <85OMS(20)416>. 

A rather indirect mode of reaction accounts for 60% of the product trans-stilbene (reaction sequence 1, 2, 4, 5, and 6 in Table VII). The importance of this path may be traced to both the low disproportionation/recombination ratio for resonance stabilized radicals, and the high rate constant for 3-bond scission of the intermediate radical recombination product, 1,2,3,4-tetraphenylbutane. Analogous decomposition routes involving formation of an adduct, followed by irreversible destruction of the adduct, may be important reaction paths in many other coal related reaction systems. 

Solar light absorption by the adsorbate may induce chemical changes in the molecule depending on its chemical nature. This process may be an important decomposition route for herbicides showing absorption spectra at A, > 295 nm. Heterocyclic N-containing compounds, phenoxy acids, dinitroanilines, propanil (S -dichloropropionanilide) and benzoic acids are very sensitive to photodecomposition. 

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