Halogen compounds specific compound

The effectiveness of aromatic or anaerobic degradation of halogenated compounds is compound bacteria specific (i.e., no universal applications). 

The high fluorine content contributes to resistance to attack by essentially all chemicals and oxidizing agents however, PCTFE does swell slightly ia halogenated compounds, ethers, esters, and selected aromatic solvents. Specific solvents should be tested. PCTFE has the lowest water-vapor transmission rate of any plastic (14,15), is impermeable to gases (see also Barrierpolymers), and does not carbonize or support combustion. 

Antimony trioxide (SbaOj). It is produced from stibnite (antimony sulphide). Some typical properties are density 5.2-5.67 g/cm- pH of water suspension 2-6.5 particle size 0.2-3 p,m specific surface area 2-13 m-/g. Antimony trioxide has been the oxide universally employed as flame retardant, but recently antimony pentoxide (SbaOs) has also been used. Antimony oxides require the presence of a halogen compound to exert their fire-retardant effect. The flame-retarding action is produced in the vapour phase above the burning surface. The halogen and the antimony oxide in a vapour phase (above 315 C) react to form halides and oxyhalides which act as extinguishing moieties. Combination with zinc borate, zinc stannate and ammonium octamolybdate enhances the flame-retarding properties of antimony trioxide. 

Gas chromatography/electrolytic conductivity detection (GC/ELCD) and gas chromatography/halogen-speciflc detection (GC/XSD) are specific for halogenated compounds and were effective for discriminating between sulfentrazone compounds and the matrix components. Operating conditions are listed below. 

Although the primary utility of active halogen compounds is to modify sulfhydryl groups in proteins or other molecules, the reaction is not totally specific. Iodoacetyl (and bromoacetyl) derivatives can react with a number of functional groups within proteins the sulfhydryl group of cysteine, both imidazolyl side chain nitrogens of histidine, the thioether of methionine, and... 

Reactive alkyl halogen compounds can be used to modify specifically hydroxyl groups in carbohydrates, polymers, and other molecules. Chloro- or bromo-derivatives of short alkyl chains... 

Detectors range from the universal, but less sensitive, to the very sensitive but limited to a particular class of compounds. The thermal conductivity detector (TCD) is the least sensitive but responds to all classes of compounds. Another common detector is the flame ionization detector (FID), which is very sensitive but can only detect organic compounds. Another common and very sensitive detector is called electron capture. This detector is particularly sensitive to halogenated compounds, which can be particularly important when analyzing pollutants such as dichlorodiphenyltrichloroethane (DDT) and polychlorobiphenyl (PCB) compounds. Chapter 13 provides more specific information about chromatographic methods applied to soil analysis. 

The noble gases are sometimes referred to as rare gases, which is not exactly accurate considering that argon makes up almost 1% of our atmosphere. Sometimes they are called inert gases, which is also not exactly correct since, under very specific conditions of temperature and pressure, some of them will combine with oxygen or the more reactive halogens to form compounds. 

Halogenated compounds Anthropogenic GOMS, ECGC, GC CIMS, specific methods... 

ESR of, 16 117 IR spectrum of, 16 117 NMR spectrum of, 16 117 peroxide derivatives of, 16 125-127, see also specific compounds preparation of, 16 115-118 properties of, 16 115-118 Raman spectra of, 16 117 reactions of, 16 118-125 with carbonyls and carbonates, 16 124 with complex anions, 16 125 with halogen-containing compounds, 16 121-123... 

---