Halogen containing compounds

Chlorine and chlorine-releasing compounds have been used in the disinfection of water supplies for more than a century. The di.scovery that hypochlorous acid (HCIO) is the active germicidal species that is formed when chlorine is dissolved in water led to the development and use of the first inorganic hypochlorite salts such as NaOCI and Ca(OCI) . Later, organic Af-chloro compounds were developed as disinfectants. These compounds release hypochlorous acid when dissidvcd in water, especially in the presence of acid. Two equally plausible mechanisms have been proposed for the germicidal action of hypochlorous acid the chlorination of amide nitrn- 

Halazone, U5P. p-Dichlorosulfamoylbenzoic acid is a white, cry.stallinc. photo.sensitive compound with a faint chlorine txlor. Halazone is only slightly. soluble in water at pH 7 but becomes very soluble in alkaline solutions. The sodium. salt of halazone is u.scd to di.sinfect drinking water. 

Oxychlorosene Sodium. Oxychlontsenc (Clorpaciin) is a complex of the sodium salt of dodccylbenzcncsulfonic acid and hypochlorous acid. The complex slowly relea.scs hypochlorous acid in. solution. 

A great deal of work has been done on the photodissociation dynamics of the halogen containing compounds. This is partially due to the production of halogen atoms and radicals that can be studied by TOF and partially due to the fact there are intense absorption bands in the ultraviolet and near ultraviolet region. These reasons, coupled with the fact that the spectroscopy of some precursor molecules is fairly well understood, have resulted in many workers looking at these compounds. Finally, some of these compounds have been studied as possible candidates for various types of lasers. 

Identification of chloro and bromo compounds is a relatively simple matter because of the unique isotopic pattern. The presence of fluoro and iodo compounds, although not easy, can be inferred from the conspicuously low [M - -1]/[M] ratio, which is due to the fact that F and I are monoisotopic. The molecular ion in aliphatic chlorides is visible only in lower monochlorides. With an increase in the number of chlorine atoms, the abundance of the molecular ion decreases further. The t-cleavage to expel a halogen atom often produces an abundant ion (e.g., the base peak in the mass spectrum of r-butyl chloride is C4H9+). The a-cleavage is of low consequence in alkyl chlorides, but the loss of an alkyl radical can be prominent when the alkyl chain is longer than four carbons the product is a flve-membered ring halonium ion  

The fragmentation reactions of alkyl bromides and iodides are similar to those of the corresponding chloro compounds. Losses of a halogen radical and an HX molecule are also observed, but to a different extent. The former is more common in bromo and iodo compounds, whereas the latter is common in chloro and fluoro compounds. 

if one understands the basic ion chemistry and the fragmentation directed by functional groups in simple molecules, one is reasonably prepared to interpret the spectra of more complex polyfunctional compounds. Further the fragmentation of EE ions is also seen in the product-ion spectra of [M - - H]+ ions produced by Cl, ESI, and FAB. 

In 1986, Sanyo Electric Company found that cyclic carbonates obtained by introducing halogens into EC can be used as solvents [84], which was followed by numerous reports on this topic [85-91]. In 1996, McMillan et al. from the National Research Council of Canada found an electrolyte that was compatible with graphite anode by utilizing fluoroethylene carbonate (60) [87] and propylene carbonate. The number of patent application for electrolytes consisting of fluoroethylene carbonate in combination with dinitrile compounds increased drastically around 2004. Details are described in Sect. 3.5.2 in the discussion of dinitriles. 

In 1999 Winter et al. from the University of Munster reported the results of analyzing SEI formed by chloroethylene carbonate (4) [89], In addition, in 1999, Inaba et al. from Kyoto University and in 2002 Arai et al. from Hitachi Limited reported that trifluoromethyl ethylene carbonate (61) forms SEI [90, 91]. 

In 1998, Ube Industries, Ltd. discovered that pentafluorobenzoates, such as methyl pentafluorobenzoate (62), can be used as additives in small quantities [92], Also, in 1999, Toyota Central R D Labs found that fluorinated benzoates, such as methyl 2,6-difluorobenzoate (63), can be used as additives in small quantities [93], and in 2002, Ube Industries, Ltd. found that pentafluorophenol compounds, such as pentafluorophenyl methanesulfonate (64) and methyl pentafluorophenyl carbonate (65), can be used as additives in small quantities [94]. 

Tschuikow-Roux, J. Phys. Chem., 1980, 84, 2146 T. Yano and E. Tschuikow-Roux, ibid., p. 3372. 

Intramolecular redistribution in S, p-difluorobenzene has been studied directly by observations of the fluorescence spectra in the presence of increasing concentrations of an efficient electronic quenching gas (in this case, 02). Under these conditions, emission is observed only from molecules that radiate during the interval between absorption and quenching, which, at high pressures of added gas (up to 30 kTorr), can be reduced to the ps time scale. Redistribution of vibrational energy is seen to take place with a rate constant of 10 s  

This year s group of publications upon the rare-gas halides includes a careful study of the ordering of the B and C states in XeCl, XeBr, and KrCl by observation of the temperature dependences of the C A and B A emissions. For KrCl, the alphabetic ordering of the states is confirmed, whereas the B state is found to lie above the C for the xenon halides. The value of Eq—Eb for XeCl, —130 35 cm differs considerably from that estimated from XeCl fluorescence measurements carried out at room temperature, 5.4 25 cm . The determination of the correct ordering of these states is of some importance, not only for overall modelling of the rare-gas halide laser systems, but also because if the C state lies sufficiently below the B, then lasing on the C A transition becomes possible, as has been shown in the successful operation of the XeF (C - A) laser at 470 nm. Measurements of the polarization of fluorescence from XeF(5) produced by 193 nm photolysis of XeFj has been 

Relaxation of the states of I and Br in collisions with H2 has been studied by optoacoustic spectroscopy and by i.r. emission techniques, respectively. The optoacoustic method allows determination of whether translational energy is absorbed or released in the collision process, and with H 2 it is found that absorption occurs, i.e. there is net translational cooling. The formation 

Br( i)-H2 system, and measurements of the rates of quenching of Br( P ) with Hj need to take the formation of the equilibrium process (13) into account. 

TABLE 2.14 Estimates of Global Tropospheric CO Budget (in Tg(CO) yr ) and Values Adopted by I FIX (2001) 

Because of its overwhelming importance in global climate, we will delay consideration of C02 until Chapter 22, where we address the global cycle of C02. 

Atmospheric halogen-containing compounds are referred to by a variety of names  

Hydrochlorofluorocarbons (HCFCs)—halocarbons containing atoms of hydrogen, in addition to carbon, chlorine, and fluorine 

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For odour analysis the most valuable detectors are FID, AED and MSD. NPD and ECD detectors are very sensitive, but limited in use to nitrogen or halogen containing compounds TCD and FUR detectors are not sensitive enough for odour analysis by direct headspace autosampling. 

The function of halogen-containing compounds as flame retardants has been explained by the radical trap theory. Liberated halogen acid (HX) competes in the above reactions for those radical species that are critical for flame propagation. 

Shokol, V.A. and Kozhushko, B.N., Phosphorohalidites and phospho-ropseudohalidites in the Arbuzov reaction with halogen-containing compounds, Russ. Chem. Rev., 54, 98, 1983. 

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... 

There are only a few reports on the dioxirane oxidation of halogen-containing compounds. The oxidation of the chloride to the hypochlorite anion by DMD (in situ) is one... 

Halogenation, hydrocarbons, 572, 575-81 Halogen-containing compounds cycUc peroxide synthesis, 225, 227,... 

Dissociation of Halogen-Containing Compounds. Halogenated compounds, particularly those containing bromine or iodine, are likely to undergo photoelimination of the halogen atom. p-Bromobutyrophenone (7) yields butyrophenone, HBr, and butyrophenones with unsaturated alkyl side chains when irradiated in toluene.25,44 The quantum yield for butyrophenone... 

The more cationic halogen containing compounds produced other products. Cobalt bis-allyliodide produced cis-polybutadiene and the even more cationic chromium, produced cyclododecatriene. Only with the more cationic system which introduced trans-structures, was cyclization and reduction of the metal able to intercept the polymerization reaction. Cyclization was not possible in the less cationic cobalt which produces all cis-polybutadiene nor was the hydride transfer possible with the less anionic chromium tris-allyl compound. 

Because only one stable electroactive product arises from the reduction of /7-chlorobenzonitrile, the interpretation of the cyclic voltammetric behavior is relatively straightforward. The fact that electron attachment to halogen-containing compounds frequently results in the cleavage of the carbon-halogen bond immediately suggests benzonitrile as a possible product. The similarity between the cyclic voltammetric behavior of benzonitrile and that of the p-chlorobenzo-nitrile reduction product supports this prediction (see Fig. 21.1). 

B. Cyclization of Halogen-Containing Compounds 1. The Hofmann-Loeffler Reaction... 

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