Oxides of chlorine

The molecules CI2O and O-CI-O are well known and need not be discussed. The preparation of CI2O3 has been reported only recently from the photolysis of OCIO. The products of the reaction are CI2, Oj, CI2O3 and CI2O6. The mechanism suggested by McHale and von Elbe is 

The CI2O3 is a dark brown solid at —45 °C and below when condensed with CI2O6. It decomposes slowly at — 45 but not at all at — 78 °C. 

Prolonged irradiation of OCIO or the photolysis of CI2-O3 mixtures produces CI2O7, which was first isolated by Michael and Conn and has been described by Goodeve and Powney. It is a colorless liquid at —78 °C, but freezes to a white solid at — ql.5°+2 °C. 

Apparently Chapman and Jones were the first to study the reaction of O3 with CI2, although Weigert had shown earlier that O3 could be photodecomposed by irradiating CI2-O3 mixtures with blue light. They found that CI2 induced the decomposition of O3, and that the reaction was so rapid they could not obtain trustworthy rate data. 

Bodenstein et al. studied the CI2-O3 reaction at 35° and 50 °C. The reaction was preceded by an induction period which varied inversely with [O3]. After the induction period, the rate law 

Despite their instability (or perhaps because of it) the oxides of chlorine have been much studied and some (such as CI2O and particularly CIO2) find extensive industrial use. They have also assumed considerable importance in studies of the upper atmosphere because of the vulnerability of ozone in the stratosphere to destruction by the photolysis products of chlorofluorocarbons (p. 848). The compounds to be discussed are  

CI2O3 a dark-brown solid (1967) which explodes even below 0°. 

CIO2 a yellow paramagnetic gas (deep-red paramagnetic liquid and solid) discovered in 1811 by H. Davy the liquid explodes above —40° and the gas at room temperature may explode at pressures greater than 50 mmHg (6.7 kPa) despite this more than half a million tonnes are made for industrial use each year in North America alone. 

CI2O4 a pale-yellow liquid (1970), CIOCIO3, which readily decomposes at room temperature into CI2, O2, CIO2 and CI2O6. 

WojTowicz, Dichlorine monoxide, hypochlorous acid and hypochlorites. Kirk-Othmer Encyclopedia of Chemical Technology, 4th edn., Wiley, New York, 1993, Vol. 5, pp. 932-68. J. J. Kaczur and D. W. Cawlfield, Chlorine dioxide, chlorous acid and chlorites, ibid., pp. 968-91. 

CI2O a brownish-yellow gas at room temperature (or red-brown liquid and solid at lower temperatures) discovered in 1834 it explodes when heated or sparked. 

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HCIO4, one of the strongest of the mineral acids. The perchlorates are more stable than the other chlorine oxyanions, ie, chlorates, CIO chlorites, CIO or hypochlorites, OCf (3) (see Chlorine oxygen acids and salts). Essentially, all of the commercial perchlorate compounds are prepared either direcdy or indirectly by electrochemical oxidation of chlorine compounds (4—8) (see Alkali and chlorine products Electrochemical processing). 

Chlorinated organics are hydrocarbons that have one or many chlorine atoms. Oxidation of chlorinated hydrocarbons yields COj, water vapor and hydrogen chloride (HCl) gas. Some typical chlorinated organics are TCE and PCE. These organics have calorific values as low as 5,000 BTU/lb. 

Table 17.19 Physical and molecular properties of the oxides of chlorine...

We next consider the synthesis and chemical reactions of the oxides of chlorine. Because the compounds are strongly endothermic and have large positive free energies of formation it is not possible to prepare them by direct reaction of CI2 and O2. Dichlorine monoxide, CI2O, is best obtained by treating freshly prepared yellow HgO and CI2 gas (diluted with dry air or by dissolution in CCI4) ... 

Similiar problems of regioselectivity as in reduction reactions are encountered in oxidation reactions of porphyrins and chlorins. The oxidation of chlorins to isobacteriochlorins can be directed by insertion of zinc(II) or nickel(II) into the macrocycle. Again here, the metal-free chlorins give the bacteriochlorins whereas the metal chlorins, e.g. 1, give isobacteriochlorins, e.g. 3.15a,b I 7... 

Gay BW Jr, Hanst PL, Bulfalini JJ, et al. 1976. Atmospheric oxidation of chlorinated ethylenes. Environmental Science and Technology 10 58-67. 

Arnett CM, JV Parales, JD Haddock (2000) Influence of chlorine snbstitnents on rates of oxidation of chlorinated biphenyls by the biphenyl dioxygenase of Burkholderia sp. strain LB400. Appl Environ Microbiol 66 2928-2933. 

Oxides of chlorine are both more numerous and more useful than those of fluorine. These oxides are the anhydrides of several important acids, and the oxyanions of those acids constitute the hypochlorites, chlorites, chlorates, and perchlorates. The first oxide of chlorine, C120 (m.p. -20 °C, b.p. +2 °C), contains chlorine in the +1 oxidation state. It can be prepared by the reaction... 

This compound is sometimes represented as [C102+][C104 ] on the basis of its reactions. One additional oxide of chlorine needs to be described. That compound is dichlorine heptoxide, C1207 (m.p. -91.5 °C and b.p. 82 °C), which is produced when HC104 is dehydrated with P4O10. 

The halogens form a number of stable oxides, but information on their thermal and photochemical decompositions in the gas phase is limited to two oxides of fluorine and several oxides of chlorine. Little research has been done on the decompositions of bromine, iodine or mixed-halogen oxides. 

Chlorine dioxide has a positive chlorine oxidation state of four (+4), which is intermediate between chlorite (+3) and chlorate (+5) ions. Oxidation of chlorine dioxide usually results in the formation of chlorite ions (e.g., CIO2 + e C102 =0.95 volts). Chlorite ions (CIO2 ) are also effective oxidizing... 

The oxidation of chlorinated compounds produces hydrogen chloride (HCl) along with the carbon dioxide and water vapor. Some catalyst aging data suggest that HCl exposure over 10,000 parts per million by volume (ppmv) for extended periods may lead to catalyst deactivation over time. 

Instead of vinegar, add salt to the distilled water. Bubbles will again appear at each terminal. If the concentration of salt is high enough, chlorine gas, CI2, is produced at the anode from the oxidation of chlorine... 

As no other case is known in which two different compounds give the same spectrum, and as the oxides of chlorine are very unstable, there is no doubt that the spectrum of one of them only was observed, that gas to which the spectrum belongs being also present when the other oxide was examined. 

A very pure product and almost theoretical yield may be obtained by the oxidation of tellurium tetrachloride with chloric acid. A slight excess of chloric acid is used to avoid the formation of any explosive oxides of chlorine. The addition of concentrated nitric acid causes precipitation of the telluric acid, which may be freed from chlorine and nitrogen oxides by drying in a vacuum. Prepared by this method the acid has the composition H2Te04.2H2O.8... 

Masten S J, Hoignd J (1992) Comparison of Ozone and Hydroxyl Radical-Induced Oxidation of Chlorinated Hydrocarbons in Water, Ozone Science Engineering 14 197-214. 

Oxidation of chlorin e6 and isochlorin e6 with permanganate gives purpurin-5 (116) and purpurin-3 (117), respectively. If pheophorbide b is oxidized, the corresponding 7-carboxylic acid (118 pheophorbide by) results saturation of the vinyl group and dehydrogenation gives pheoporphyrin by (119) which can be converted into demethyldeoxyphylloerythrin... 

Chlorine Monoxides See under Chlorine Oxides Chlorine Oxides, The oxides of chlorine are all endothermal compds, i.e, they are formed with absorption of energy and are so unstable that they readily decomp spontaneously with evolution of heat, sometimes with expl violence. None of the oxides can be prepd by the direct union of chlorine 8c oxygen, but... 

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