Preliminary thermolysis studies

We report here some of our recent results in the second of these areas. Specifically, the synthesis, structure, reactivity, and preliminary thermolysis studies of several new mono-and diborylamines based on the 2-phenyl-l,3,2-diazaboracyclohexane ring system (1) are described. 

We report here the results of our recent studies of poly(alkyl/arylphosphazenes) with particular emphasis on the following areas (1) the overall scope of, and recent improvements in, the condensation polymerization method (2) the characterization of a representative series of these polymers by dilute solution techniques (viscosity, membrane osmometry, light scattering, and size exclusion chromatography), thermal analysis (TGA and DSC), NMR spectroscopy, and X-ray diffraction (3) the preparation and preliminary thermolysis reactions of new, functionalized phosphoranimine monomers and (4) the mechanism of the polymerization reaction. 

The trimeric indium antimonide single-source precursor [Et2InSb(SiMe3)2]3, prepared from Et2InCl and Sb(SiMe3)3, was shown in a preliminary study to form InSb nanocrystals (average particle size 10 nm) by solid-state thermolysis at 400 °C under a static vacuum. However, the particles were contaminated with elemental indium.399... 

The numerous studies ofthe thermolysis reactions of Al(OR)3 have been summarized in the review by Piekos [1301]. They permit a conclusion that the the starting temperatures of decomposition are not constant but depend on the rate of heating and the time of preliminary treatment. The general scheme of decomposition proposed by Tishchenko includes for the first step the formation of ethers and A10 (0R)3.n. Next comes the dehydration of ethers ... 

In the case of PSSZ a more extensive study was carried out. In particular, it was shown that the nitrogen content of the ceramic is in good correlation with the value of x when x < 0.75. For X > 0.5 Si-Si-Si sequences were hardly detected. A PSSZ prepared with equimolar amounts of Me2SiCl2 and (ClHMeSi)2NH was converted into PCSZ upon thermolysis (temperature of the bath 425 °C, 8h), cross-linked by y-irradiation, then pyrolyzed to afford SiCN-based material containing a very small amount of oxygen [4a]. In a preliminary study carried out at the Laboratoire des Composites Thermostructuraux, F-33600 Pessac, France (Prof R. Naslain), SiCN fibers were obtained (tensile strength 2 400 MPa Young s modulus 235 GPa). 

Some stages of this multistep process (especially the particle growth) are similar to the mechanism of the metal vapor condensation on the polymer [1]. The thermolysis in the presence of polymers was in greater extent studied for carbonyls of cobalt (see, for example, references 56 and 57) and iron [53, 56-58] (Table 3.7) when the process proceeds by a direct Ma(CO) vaporization over polymers or by a preliminary adsorption on them. 

Thermolysis of sparteine N-oxides occurs readily when an aqueous acidic solution is heated in the presence of an excess of chloride ion. In the case of the N-16-oxide (7), alkaline work-up gives the carbinolamine (8) a study of the effect of the concentration of chloride ion and of the pH of the medium on the reaction rate led to the proposed mechanism (Scheme 2). Sparteine N-1-oxide and a-isosparteine N-1-oxide undergo similar jS-elimination reactions, but the products are enamines. A preliminary investigation of the thermolysis of sparteine epi-N- 16-oxide (9) showed that the carbinolamine (8) was the sole product, formed apparently by a yn-elimination. 

Preliminary study of pure mercaptide thermolysis behavior by thermal analysis... 

PRELIMINARY STUDY OF PURE MERCAPTIDE THERMOLYSIS BEHAVIOR 619... 

The mercaptide thermolysis may behave differently in the presence or absence of polymers [Conte et al., 2007]. However, in most cases, the inorganic phase generated by the thermal degradation of mercaptide molecules dissolved in polymer corresponds exactly to that resulting from the thermal degradation of pure mercaptide. Consequently, a preliminary study of neat mercaptide thermolysis by thermal analysis approaches [differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA)] is usually performed before nanocomposite preparation and characterization. 

The use of solar energy for experimental studies on H2S uncatalysed thermolysis indicated that a high degree of chemical conversion was attainable and that the reverse reaction during quench was negligible [6, 65, 66]. The recommended process temperature would be between 1300 and 1500°C. However, a preliminary economic assessment indicated that the capital cost of a plant employing effusion to separate H2 and H2S would be up to ten times higher than a similar capacity Claus plant. 

A key issue in studies of thermolysis kinetics in hitherto unexplored systems, including Hf-containing polymers, is the optimization of the experimental procedure. Preliminary thermodynamic analysis of the Hf-C-H-0 system offers the possibility of establishing the temperature stability limits of HfC and HfO. Earlier, thermodynamic studies of the Hf-C-H-O system were carried out in relation to hafnium acetylacetonate, which is used to prepare HfC [33]. The most convenient approach to producing hafnium-containing nanocomposites with the aim of... 

Instructions for the TLC of the phenols expected as products of thermolysis were abundantly available already Preliminary experiments owed that the phenol mixtures to be expected were best separated by double development using benzene in a run of IS cm. For speed and reproducibility this solvent gives the best results although superposition of phenol with m- and p-cresols and also some higher alkyl-phenols (cf. Table 8) is unavoidable. Partition-TLC on layers impregnated with formamide has been used successfully to separate these critical homolc ous or isomeric phenols 3°). We have studied thoroughly the scope of application and... 

---