Chlorine oxidation state

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... 

Lead(IV) oxide is found to have a considerable oxidising power, again indicating that the oxidation state +2 is generally more stable for lead than oxidation state +4. Concentrated hydrochloric acid, for example, reacts with PbO at room temperature to form lead(II) chloride and chlorine ... 

Chlorine reacts with most elements, both metals and non-metals except carbon, oxygen and nitrogen, forming chlorides. Sometimes the reaction is catalysed by a trace of water (such as in the case of copper and zinc). If the element attacked exhibits several oxidation states, chlorine, like fluorine, forms compounds of high oxidation state, for example iron forms iron(III) chloride and tin forms tin(IV) chloride. Phosphorus, however, forms first the trichloride, PCI3, and (if excess chlorine is present) the pentachloride PCI5. 

Bromine has a lower electron affinity and electrode potential than chlorine but is still a very reactive element. It combines violently with alkali metals and reacts spontaneously with phosphorus, arsenic and antimony. When heated it reacts with many other elements, including gold, but it does not attack platinum, and silver forms a protective film of silver bromide. Because of the strong oxidising properties, bromine, like fluorine and chlorine, tends to form compounds with the electropositive element in a high oxidation state. 

Originally, general methods of separation were based on small differences in the solubilities of their salts, for examples the nitrates, and a laborious series of fractional crystallisations had to be carried out to obtain the pure salts. In a few cases, individual lanthanides could be separated because they yielded oxidation states other than three. Thus the commonest lanthanide, cerium, exhibits oxidation states of h-3 and -t-4 hence oxidation of a mixture of lanthanide salts in alkaline solution with chlorine yields the soluble chlorates(I) of all the -1-3 lanthanides (which are not oxidised) but gives a precipitate of cerium(IV) hydroxide, Ce(OH)4, since this is too weak a base to form a chlorate(I). In some cases also, preferential reduction to the metal by sodium amalgam could be used to separate out individual lanthanides. 

The preparation of mercuric chloride is identical to the chamber method for mercurous chloride, except that an excess of chlorine is used to ensure complete reaction to the higher oxidation state. Very pure product results from this method. Excess chlorine is absorbed by sodium hydroxide in a tower. 

Ternary compounds are also named by citing the more electropositive constituent first. The various oxidation states of the more electropositive element are designated by a system of prefixes and terminations added to a stem characteristic of the element, except in the case of coordination compounds (qv). Examples are as follows (see Chlorine oxygen acids and salts) ... 

Rhenium Halides and Halide Complexes. Rhenium reacts with chlorine at ca 600°C to produce rheniumpentachloride [39368-69-9], Re2Cl2Q, a volatile species that is dimeric via bridging hahde groups. Rhenium reacts with elemental bromine in a similar fashion, but the metal is unreactive toward iodine. The compounds ReCl, ReBr [36753-03-4], and Rel [59301-47-2] can be prepared by careful evaporation of a solution of HReO and HX. Substantiation in a modem laboratory would be desirable. Lower oxidation state hahdes (Re X ) are also prepared from the pentavalent or tetravalent compounds by thermal decomposition or chemical reduction. 

The performance of many metal-ion catalysts can be enhanced by doping with cesium compounds. This is a result both of the low ionization potential of cesium and its abiUty to stabilize high oxidation states of transition-metal oxo anions (50). Catalyst doping is one of the principal commercial uses of cesium. Cesium is a more powerflil oxidant than potassium, which it can replace. The amount of replacement is often a matter of economic benefit. Cesium-doped catalysts are used for the production of styrene monomer from ethyl benzene at metal oxide contacts or from toluene and methanol as Cs-exchanged zeofltes ethylene oxide ammonoxidation, acrolein (methacrolein) acryflc acid (methacrylic acid) methyl methacrylate monomer methanol phthahc anhydride anthraquinone various olefins chlorinations in low pressure ammonia synthesis and in the conversion of SO2 to SO in sulfuric acid production. 

In the diaziridine field many compounds are known bearing N-YL, A/-alkyl and A-acyl groups, but here no dramatic changes in reactivity are caused by A-substituents. N-Aryldiaziridines are underrepresented. The ring carbon is in the oxidation state of a carbonyl compound or, in the diaziridinones (5) and the diaziridinimines (6) that of carbonic acid. In single cases, diaziridine carbon bears chlorine or fluorine. 

The formation of several oxidation states is typical of the elements on the right side of the periodic table. We have already discussed in Chapter 19 the fact that chlorine can exist in the + 1, +3, +5, and +7 oxidation states as well as in the — 1 state. In its compounds, chlorine is most often found in the — 1 state. This preponderance of — 1 compounds shows that elemental chlorine behaves as an oxidizing agent in most of its reactions. 

However, Schwarz s suggestion to focus on bonded atoms rather than neutral atoms also runs into a major problem because the atoms of any element typically show a large variety of oxidation states. For example, atoms of chlorine occur in the zero oxidation state in the chlorine molecule, the —1 state in NaCl, +1 in HOC1, +3 in HC102, +5 in HCIO3, and +7 in HCIO4. 

The symmetric series provides functional cyclohexadienes, whereas the non-symmetric one serves to build deuterated and/or functional arenes and tentacled compounds. In both series, several oxidation states can be used as precursors and provide different types of activation. The complexes bearing a number of valence, electrons over 18 react primarily by electron-transfer (ET). The ability of the sandwich structure to stabilize several oxidation states [21] also allows us to use them as ET reagents in stoichiometric and catalytic ET processes [18, 21, 22]. The last well-developed type of reactions is the nucleophilic substitution of one or two chlorine atoms in the FeCp+ complexes of mono- and o-dichlorobenzene. This chemistry is at least as rich as with the Cr(CO)3 activating group and more facile since FeCp+ activator is stronger than Cr(CO) 3. 

Chlorine can exist in both positive and negative oxidation states. What is the maximum (a) positive and (b) negative oxidation number that chlorine can have (c) Write the electron configuration for each of these states, (d) Explain how you arrived at these values. 

Chlorate ions, CIO (oxidation state +5), form when chlorine reacts with hot concentrated aqueous alkali ... 

Eehrmann R, Bjerrum NJ, Poulsen EW (1978) Lower oxidation states of sulfur. 1. Spectrophotometric study of the sulfur-chlorine system in molten sodium chloride-aluminum chloride (37 63 mol%) at 150 °C. Inorg Chem 17 1195-1200... 

The oxidation by Mn(lII) chloride involves three complexes and the kinetic data of Taube " are summarised in Table 15. The greater thermal stability of the /m-complex is considered to result from the lowering of the free energy relative to the transition state as compared with bis- and mono-complexes. The study of MnC204 was based on the Mn(III)-catalysed chlorine oxidation of oxalic acid. ... 

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