Flame chemical synthesis

Decomposition Flame Arresters Above certain minimum pipe diameters, temperatures, and pressures, some gases may propagate decomposition flames in the absence of oxidant. Special in-line arresters have been developed (Fig. 26-27). Both deflagration and detonation flames of acetylene have been arrested by hydrauhc valve arresters, packed beds (which can be additionally water-wetted), and arrays of parallel sintered metal elements. Information on hydraulic and packed-bed arresters can be found in the Compressed Gas Association Pamphlet G1.3, Acetylene Transmission for Chemical Synthesis. Special arresters have also been used for ethylene in 1000- to 1500-psi transmission lines and for ethylene oxide in process units. Since ethylene is not known to detonate in the absence of oxidant, these arresters were designed for in-line deflagration application. 

As a result, there is a unique chance to utilize alternative reaction routes for chemical synthesis that so far have not been applied commercially, for reasons of safety or difficulties in process control or because it is fundamentally impossible to realize such reaction routes using macroscopic devices. This is the case, in particular, for controlled reactions in the explosive regime (Figure 6) (15). This is accessible by means of microreaction devices, since, due to their small characteristic dimensions, they act like flame retention baffles. Moreover, the small dimensions allow reactions to be performed at extremely high pressure, which is of importance for chemical processes using supercritical solvents. 

Many catalysts used in chemical synthesis can be treated in the same way, often the nitrous oxide/acetylene flame is used because of the refractory nature of the elements to be determined. Harrington and Bramstedt [56] have determined rhenium in electro-chemical surface catalysts by stripping the coating with molten potassium hydroxide/ potassium nitrate. This melt was extracted with hydrochloric acid, the residue was fused with sodium peroxide for further rhenium determination. Titanium, being the substrate on which the catalyst was coated, was added to the standards, an air/acetylene flame and 343.3 nm were used for the finish. 

SAFETY PROFILE Olefinic impurities may lend a narcotic effect or it may act as a simple asphyxiant. A very dangerous fire hazard when exposed to heat or flame. Can react with oxidizing materials. To fight fire, use CO2, dry chemical, water spray. Used as a fuel refrigerant, propellant, and raw material in chemical synthesis. 

Other Specialty Chemicals Synthesis of chlorprene Synthesis of allyltribromophenol, a flame retardant polymer Synthesis of prepolymers based on natural resources like lignin... 

M. C. Heine, S. E. Pratsinis Droplet and particle dynamics during flame spray synthesis of nanoparticles. Industrial Engineering Chemical Research 44, 6222-6232 (2005). 

An important topic of research is the introduction of the catalyst in the microreactor. In brief solid catalysts can be incorporated on the interior of micromachined reaction channels, prior to or after closure of the channel, by a variety of strategies anodic oxidation, plasma-chemical oxidation, flame combustion synthesis, sol-gel techniques, impregnation, wash coating, (electro-)plating, aerosols, brushing, chemical vapor deposition, physical vapor deposition and nanoparticle deposition or self-assembly. Some of these methods can be applied in combination with photolithography or shadow masking. 

Building on our experience with IGC and CVC, we have replaced the heat source by a flame in the Combustion Flame - Chemical Vapor Condensation (CF-CVC) technique. This technique offers several advantages over previous methods and has the potential to continuously generate non-agglomerated powders at high rates typical for industrial processes. These advantages have been exploited in other research and commercial flame synthesis processes for the production of diamond, carbon black, other particulates, and a variety of thin films, but not to date for the large scale production of nanoscale powders. 

Vinyl chloride has gained worldwide importance because of its industrial use as the precursor to PVC. It is also used in a wide variety of copolymers. The inherent flame-retardant properties, wide range of plastici2ed compounds, and low cost of polymers from vinyl chloride have made it a major industrial chemical. About 95% of current vinyl chloride production worldwide ends up in polymer or copolymer appHcations (83). Vinyl chloride also serves as a starting material for the synthesis of a variety of industrial compounds, as suggested by the number of reactions in which it can participate, although none of these appHcations will likely ever come anywhere near PVC in terms of volume. The primary nonpolymeric uses of vinyl chloride are in the manufacture of vinyHdene chloride and tri- and tetrachloroethylene [127-18-4] (83). 

Lindane is one of eight different hexachlorocyclohexane (HCH), C H Cl, isomers and its Chemical Abstract n.2cniQ is la, 2a 3P, 4a, 5a 6P-hexachlorocyclohexane [58-89-9] (y-HCH or y-BHC, ben2ene hexachloride) (80). Commercial products containing lindane are marketed as either a mixture of isomers or as the pure y-BHC isomer. Not unexpectedly, lindane is a highly stable lipophilic compound and it has been used extensively worldwide as an insecticide. In contrast, hexachloropentadiene, C Cl, is an extremely reactive industrial intermediate used as a chemical intermediate in the synthesis of a broad range of cyclodiene-derived pesticides, which include endosulfan, endrin, heptachlor, and several different organohalogen flame retardants (81). 

Ref 130, p 220) and by Great Britain (Vol 3, C498-R). These rockets utilized BlkPdr as proplnt, fuse (Ref 122) and as an expl. Up to the middle of the last century the history of pyrotechnics is the history of BlkPdr. Even now, as will be discussed in Section 7, large quantities of BlkPdr are used as an igniter. By the late 18 th century a new age in pyrotechnics commenced thru the synthesis of K chlorate (Vol 2, C190-R), the discovery of Fulminates (Vol 6, F216-R) and the identification of the minerals which would impart color to a flame. The discovery of electricity brought about pure chemicals and hence, better flame colors, new oxi-... 

The importance of adequate support by database reference material is well illustrated with the following case. After chromatographic separation (TLC, CC), the combination of >H/13C NMR, DI-MS (El), FTIR and HPLC (IJV/VIS, DAD and MS) a flame retardant in a Japanese polypropylene TV cabinet on the European market was identified as tetrabromobisphenol-,S -bis-(2,3-dibromopropyl ether) (TBBP-S) [168]. The result was verified by synthesis of reference material the product was finally identified as Non Nen 52 from Marubishi Oil Chemical Co., Ltd (Osaka), not registered in any spectral database. 

Uses. As a chemical intermediate for organic synthesis and as a laboratory reagent formerly used as a solvent and flame retardant. Currently, the major source of bro-modichloromethane in the environment is... 

Uses/Sources. Intermediate in organic synthesis, especially production of toluene diisocyanate and polymethylene poly-phenylisocyanate in metallurgy to separate ores by chlorination of the oxides and volatilization occurs as a product of combustion whenever a volatile chlorine compound comes in contact with a flame or very hot metal originally manufactured as an agent for chemical warfare during World War I... 

Jones AC (2002) Molecular design of improved precimsors for the MOCVD of electroceramic oxides. Journal of Materials Chemistry 12(9), 2576-2590 Jones AC, Chalker PR (2003) Some recent developments in the chemical vapour deposition of electroceramic oxides. Journal of Physics D-Applied Physics 36(6), R80-R95 Kammler HK, Madler L, et al (2001) Flame synthesis of nanoparticles. Chemical Engineering Technology 24(6), 583-596... 

Mueller R, Madler L, et al (2003) Nanoparticle synthesis at high production rates by flame spray pyrolysis. Chemical Engineering Science 58(10), 1969-1976... 

This CVD procedure is somewhat different from that used to deposit semiconductor layers. In the latter process, the primary reaction occurs on the substrate surface, following gas-phase decomposition (if necessary), transport, and adsorption. In the fiber optic process, the reaction takes place in the gas phase. As a result, the process is termed modified chemical vapor deposition (MCVD). The need for gas-phase particle synthesis is necessitated by the slow deposition rates of surface reactions. Early attempts to increase deposition rates of surface-controlled reactions resulted in gas-phase silica particles that acted as scattering centers in the deposited layers, leading to attenuation loss. With the MCVD process, the precursor gas flow rates are increased to nearly 10 times those used in traditional CVD processes, in order to produce Ge02-Si02 particles that collect on the tube wall and are vitrified (densified) by the torch flame. 

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