Pyrolysis Techniques

Synthesis depends on gas-phase pyrolysis techniques , and interconversion is by electrochemical oxidation . Understanding of the mechanisms by which the boranes interconvert and build up into larger clusters is growing . 

A pyrolysis technique was investigated as a method for the chemical recycling of glass fibre-reinforced unsaturated polyester SMC composites. The proeess yielded liquid products and gases and also a solid residue formed in the pyrolysis of glass fibres and fillers. The solid residue was used as a reinforeement/filler in unsaturated polyester BMC composites, and the influenee on mechanical properties was studied in comparison with BMC prepared entirely from virgin materials. 

K. J. Vooehees, "Analytical Pyrolysis Techniques and Application", Butterworth, London, UK, 1984. 

Gas chromatography is widely applied in the paint and varnish industry for analysis of solvents, oils, resins, plasticisers and polymers (by pyrolysis techniques). GC-TCD and GC-FTD on capillary and packed columns are used for direct determination of solvents in paints [143,144], DIN ISO 11890-2 describes an officially approved GC test procedure for solvents in paints and varnishes (VOCs 0.1-15%). 

Espitalie, J., Marquis, F., Barsony, J., "Geochemical Logging by the Oil Show Analyzer" Analytical Pyrolysis - Techniques et Applications - Voorhees, Ed. Butterworth, Londres, (1984) ... 

Cavitation bubble pyrolysis technique Fe, Fe/Co, M02C, CoFe204 [8-10]... 

Thermal treatment synthesis technique of mists formed from ultrasonic atomizer (Ultrasonic spray pyrolysis technique) Y203-Zr02, NiO, ZnS, BaTi03-SrTi03, MoS2, BiV04 [11-14]... 

Fiber reinforced ceramics such as C/SiC, SiC/SiC can be manufactured by the polymer infiltration and pyrolysis technique at reasonable cost. The developed production technique allows the manufacturing of large and complex structures comparable to fiber-reinforced plastics. The material has excellent high temperature resistance, low density, and good damage tolerance, and is therefore well... 

One of the main problems of the pyrolysis technique is related to the low volatility of pyrolysis products arising from natural and some synthetic macromolecules. In fact, the polar acidic, alcoholic and aminic moieties are not really suitable for gas chromatographic analysis. Their poor volatility and their polarity cause a rather low reproducibility of the pyrograms, low sensitivity for specific compounds, and strong memory effects. Memory effects need to be borne in mind when the pyrolysis of polar molecules is performed. Polar pyolysis products may not be completely eluted by the gas chromatographic column, and... 

Huang Y, Eglington G, van der Hage ERE, Boon JJ, Bol R, Ineson P (1998) Dissolved organic matter and its parent organic matter in grass upland soil horizons studied by analytical pyrolysis techniques. Eur J Soil Sci 49 1-15... 

The polyaromatic hydrocarbons in the soil sample were quantitated by using an external standard of anthracene. The results reportedly for a polluted soil and sediment sample indicate that this flash evaporation-pyrolysis technique combined with gas chromatography-mass spectrometry is a valuable tool for rapidly screening polluted samples for virtually all types of anthropogenic contaminants except for heavy metals. 

The next three procedures provide useful synthetic intermediates. A stereospecific synthesis of ETHYL (Z)-3-BROMO-2-PROPENOATE affords an alternative vinyl bromide partner for the coupling chemistry in the preceding procedure. A very simple but elegant illustration of the flash vacuum pyrolysis technique is used to prepare BENZOCYCLOBUTENONE from o-toluoyl chloride. Another member of the functionalized indole family of synthetic intermediates is presented in a four-step procedure for 5-METHOXYINDOLE-2-ACETIC ACID METHYL ESTER. 

In the mid-1980s, Wentrup and co-workers, using flash vacuum pyrolysis techniques, were able to obtain direct evidence for N2S (29) as an unstable, primary product in the pyrolysis of 5-phenylthiatriazole <86JOC1908, 88JA3458). 

Experimentally, the kinetic data obtained from the pyrolysis of cyclobutane to ethene between 696 and 1007"C using a very low-pressure pyrolysis technique is consistent with a 1,4-diradical reaction route.82 A diradical process is also favored over a concerted pathway for the formation of nearly 1 1 mixtures of cis- and tranj-but-2-enes and [l,2-2H2]ethene from the thermal rupture of cb-l,2-dimethyl[cw,firn /-3,4-2H2]cyclobutane (5),83... 

The flash-pyrolysis technique has been especially useful for the synthesis of unstable benzo[c]furans the 1-methyl, 1,3-diinethyl, and 1-benzyl derivatives have been prepared in this way in quantitative yield. The UV and H-NMR spectra are in accord with their structures. These compounds are extremely reactive, resinifying rapidly on standing at room temperature. With 7V-phenylmaleimide, the Diels-Alder adducts 88 (endo, mp 201-201.6°C, 18%), 89 (exo, mp 153-153.5 C, 14%) and 90 [endo, mp 215 217 C. 60% (includes both endo and exo)] are obtained 87 (R = R = H, =... 

A pyrolysis technique has been employed to incorporate perhydropyrimidin-2-one (cyclic urea) groups into a polymer framework (74MI11108). Pyrolysis of po y(/-butyl A/-vinylcarba-... 

The a-pyrone adduct (430) on heating gave benzo[c]furan, isolated in 30% yield. Pyrolysis of l,4-oxido-l,2,3,4-tetrahydronaphthalene (431) at 650 °C and 0.1 Torr results in quantitative formation of benzo[c]furan. 1-Methyl-, 1,3-dimethyl-and l-benzyl-benzo[c]furanshave been prepared in quantitative yield by the flash pyrolysis technique (76TL2507). 

Two methods have been employed for the synthesis of thieno[3,2-fc]pyridine which use gas-phase pyrolysis techniques. Klemm and coworkers starting with 2-vinylpyridine prepared (261) in a manner (Scheme 81) (68JHC883) strictly analogous to the synthesis of thieno[2,3-c]pyridine (Scheme 69). Another convenient route to (261) consists of the... 

Pyrolysis techniques developed by Kroto et al. to produce sulphur and selenium doubly bonded species in a low pressure flow system where the lifetimes are of the order of seconds, enabled species such as H2CS ( ), F2CS (6), CH3CHS (7), CHaCHSe (8J, ... 

Several papers in this book and in the recent literature (3) discuss use of pyrolysis techniques coupled with gas chromatography and mass spectrometry to determine forms of organically bound sulfur, but these methods introduce an uncertainty due to the possible interconversion of these sulfur forms during the heating step. For example, it has been shown that when benzyl sulfide was heated to 290°C, tetraphenyl thiophene, hydrogen sulfide and stilbene were produced (4). Coupled with heat and mass transport limitation considerations, particularly for viscous liquids and solids, it is not unreasonable to question whether at least some of the thiophenic forms observed by these techniques were produced during the analysis and may not have been present in the original sample. 

As a recent modification, the Graebe-Ullmann synthesis of. y-carbolines under microwave irradiation has been conducted (Scheme 37). Yields of the reaction were comparable to those obtained by conventional heating at 150-210°C (30-81% yield), but the reaction times were significantly reduced <93TL2673>. Similarly, using flash vacuum pyrolysis techniques, nitroar-ylbenzotriazoles have been converted to pyridoindoles <88BSB245>. 

Correa-Lozano, B., Comninellis, C. and De Battisri, A. (1996), Physicochemical properties of Sn02-Sb205 films prepared by the spray pyrolysis technique. J. Electrochem. Soc., 143(1) 203-209. 

Tromp PJJ (1987) Coal pyrolysis - basic phenomena relevant to conversion processes Dissertation, University Amsterdam, FOM-Institute, Amsterdam Voorhees KJ (1984) Analytical pyrolysis - techniques and applications Butterworths, London 486 pp... 

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