Decomposition patterns, thermal

Water is, of course, a particularly difficult solvent to remove from solvates (i.e., hydrates). Thermal decomposition patterns for solvates containing such solvents as tetrahydrofuran suggest that thermal treatment of such solvates may prove a feasible route to anhydrous trihalides. 

Thiadiazoles are generally quite stable to heat due to the aromatic nature of the ring. Their thermal stability is influenced by the nature of the 3- and 5-substituents <65AHC(5)l 19>. Mass spectral decomposition patterns of substituted 1,2,4-thiadiazoles are discussed in Section 4.08.3.5. Photochemical behavior of 1,2,4-thiadiazoles has not been studied to date. 

The probable thermal decomposition patterns of CaC204H20 deduced using the thermogram (obtained in air) given below (Atomic weights of Ca, C and O may be assumed to be 40,12 and 16 respectively). 

A similar decomposition pattern is observed with thermally generated alkoxy radicals whose order of ease of radical elimination increases in the manner H < CsH6 < CH3 < C2H5 < (CH3)2CH < (CH3)3C < ring fission. See ref. 23 also, E. R. Bell, J. H. Raley, F. F. Rust, F. H. Seubold, and W. E. Vaughan, Discussions Faraday Soc., 10, 242 (1951). 

The products of lipid oxidation in monolayers were also studied. Wu and coworkers (41) concluded that epoxides rather than hydroperoxides might be the major intermediates in the oxidation of unsaturated fatty acids adsorbed on silica, presumably because of the proximity of the substrate chains on the silica surface. In our work with ethyl oleate, linoleate and linolenate which were thermally oxidized on silica, the major decomposition products found were those typical of hydroperoxide decomposition (39). However, the decomposition patterns in monolayers were simpler and quantitatively different from those of bulk samples. For example, bulk samples produced significantly more ethyl octanoate than those of silica, whereas silica samples produced more ethyl 9-oxononanoate than those of bulk. This trend was consistent regardless of temperature, heating period or degree of oxidation. The fact that the same pattern of volatiles was found at both 60°C and 180°C implies that the same mode of decomposition occurs over this temperature range. 

Characteristic thermogram patterns were obtained10 by TPD MS, which allows us to observe details of BSA decomposition and the two monosaccharides in the condensed state. Thermal decomposition patterns for several components of the BSA mass spectrum in condensed and adsorbed states are presented in Figures 4 and 5. After individual adsorption of BSA on fumed silica the pattern of BSA decomposition changed slightly, and could still be used to identify the nanocomposites. The only exception is the temperature dependence of mass line at 34 M/z, which corresponds to the molecular ion H2S+ resulting from decomposition of sulfur-containing amino acids of BSA. 

Similar decomposition patterns can be proposed for secondary radicals derived from 2 in the initiating hydrogen abstraction Step 1. Thermal aromatization of 6-ring cyclic dienes containing one exocyclic and one endocyclic double bonds is a facile process at 550°-600°C. The reaction involves fast double bond isomerization to a conjugated cyclohexadiene, followed by dehydrogenation (30, 31,32). 

Thermal Decomposition Patterns in Methylammonium Cation-Exchanged Y-Type Faujasites... 

We now report results of a study of the thermal decomposition patterns in the 4 methyl-substituted ammonium (MA) exchanged Y-type faujasites, detailed transformation of the TTMA form, and the resulting generation of protonic acidity. 

The reactivity of the ethenediazonium salt 9.100 towards the nucleophiles mentioned shows that it has the properties of the corresponding carbocation, since it can ethylate the nucleophile and is prone to attack at the C()ff)-atom of the original ethene-l-diazonium ion. The thermal decomposition pattern is typical of that for an oxonium salt. Reactions with amines are similar to those of ketene acetals. No product that could be explained in terms of an azo coupling reaction, e.g., with 2-naphthol, could be observed. The electrophilicity of the diazonio group is, therefore, low. N-Azo coupling products with azide ions have been postulated with good arguments, however, by Kirmse and Schnurr (1977) with certain short-lived ethene diazonium intermediates produced from nitroso oxazolidones. 

E. Dovble-Bond Addition Reactions Reactions of recoil tritium atoms in alkenes have been studied and have brought to light an additional reaction type. The energetic tritium atom can add to the double bond. Urch and Wolfgang (1959) have substantiated this hot addition by studying scavenger and moderator effects in alkenes. Decomposition of the hot radical once formed follows a pattern similar to that of the decomposition of thermally excited free radicals, namely... 

The principal applications of TGA/DTGA in polymers are (2) determination of the thermal stability of poljuners, (2) compositional analysis, and (3) identification of pol5miers from their decomposition pattern. Also, TGA curves are used to determine the kinetics of thermal decomposition of poljuners and the kinetics of cure... 

Figine 10 compares the thermal stability of the polymer matrix of GMAEVC and epoxy resin cured at different temperatures. The cured matrix shows thermal stability up to 300°C and three decomposition products between 300°C-400°C. The decomposition pattern of the matrix cured at higher temperature shows a decrease of the peak at 316°C and an increase of the peak at 381°C. This result indicates that curing at higher temperature produces high molecular weight products more abundantly than the matrix cured at lower temperature. 

From the thermal decomposition of mono- and dihydrazinium phosphates it appears that both salts decompose through the intermediate formation of N2H5HP2O6 leading to metaphosphoric acid. Further, their decomposition patterns follow the corresponding decomposition pattern of ammonium salts. However, hydrazinium phosphate salts are of interest as superior flame retardants because of the hydrophilic nature or hygroscopic property of the hydrazinium ion. This supports dehydration more efficiently and limits the production of hydrocarbon gases, thereby promoting flame retardancy (see Chapter 6, Section 6.2.4). 

Isoxazoles, isoxazolines, isoxazolidines and benzisoxazoles are all thermally stable, distilling without decomposition, but the stability of the system depends on the substitution pattern. For example, aminoisoxazoles distill unchanged but the isoxazole carboxylic acids usually decompose at or above their melting points without giving the corresponding isoxazole. 

Chain reactions such as those described above, in which atomic species or radicals play a rate-determining part in a series of sequential reactions, are nearly always present in processes for the preparation of thin films by die decomposition of gaseous molecules. This may be achieved by thermal dissociation, by radiation decomposition (photochemical decomposition), or by electron bombardment, either by beams of elecuons or in plasmas. The molecules involved cover a wide range from simple diatomic molecules which dissociate to atoms, to organometallic species with complex dissociation patterns. The... 

Interaction between niobium oxide and fluorides, chlorides or carbonates of alkali metals in an ammonium hydrofluoride melt, yielded monooxyfluoroniobates with different compositions, MxNbOF3+x, where they were subsequently investigated [123-127]. According to DTA patterns of the Nb205 - 6NFL HF2 - 2MF system, (Fig. 18) a rich variety of endothermic effects result from the formation of ammonium monooxyfluoroniobate, its thermal decomposition and its interaction with alkali metal fluorides. The number of effects decreases and separation of ammonium ceases at lower temperatures and when going from lithium to cesium in the sequence of alkali metal fluorides. 

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