Chlorine oxyanions

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). 

The following group of isoelectronic sulfur and chlorine oxyanions provides another illustration of molecular geometries that are based on tetrahedral orbital geometry. 

Knowing the names of similar chlorine oxyanions and acids, deduce the names of the following 10 , IO2 , IO3 , IO4 , HIO, HIO2, HIO3, HIO4. 

The basicity of the chlorine oxyanions also decreases as the number of lone O atoms increases. The oxyanion in which the central atom has the larger oxidation number has the larger number of lone O atoms for participating in extension of the tt bond, and therefore is the weaker base ... 

Oxyanions consist of an atom of an element plus some number of atoms of oxygen covalently bonded to it. The name of the anion is given by the name of the element with its ending changed to either -ate or -ite. In some cases, it is also necessary to add the prefix per- or hypo- to distinguish all the possible oxyanions from one another. For example, there are four oxyanions of chlorine, which are named as follows ... 

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... 

Structure (3.226c), for example, depicts a central heptavalent Cl atom (Fa = 7), exceeding the normal valence octet by six electrons (These excess electrons are assumed to be accommodated in chlorine 3d orbitals, whereas d-orbital participation is prevented in first-row compounds.) Hypervalent structures such as (3.226a)-(3.226c) are claimed to be justified by the electroneutrality principle, which stipulates that second-row central atoms have zero formal charge (whereas first-row oxyanion Lewis structures commonly violate this principle).148... 

Hendy CH, Wilson AT (1968) Paleoclimatic data from speleothems. Nature 219 48-51 Heraty LJ, Fuller ME, Huang L, Abrajano T, Sturchio NC (1999) Isotopic fractionation of carbon and chlorine by microbial degradation of dichlormethane. Org Geochem 30 793-799 Herbel MJ, Johnson TM, Oremland RS, Bullen TD (2000) Fractionation of selenium isotopes during bacterial respiratory reduction of selenium oxyanions. Geochim Cosmochim Acta 64 3701-3710... 

There are only three oxyanions that form anhydrous salts chlorites (C102), chlorates (C10(), and perchlorates (C104). Their stability increases with the increasing oxidation state of the halogen. There is no clear evidence for the existence of stoichiometric, anhydrous hypochlorites (CIO). Even for the few reported salts (NaCIO, Ca(C10)2) one finds reports of smell of chlorine, indicating continuous decomposition at ambient temperature. 

The chief difference between the oxyanions of iodine and those of chlorine and bromine is the large number of periodates (see below). Otherwise, differences between the respective anions are largely accounted for by the larger size of iodine and its more metallic character. 

Ans. Assuming complete neutralization (or even oxidation of the Cl to CI2), we can see that 1 mol HCl will react with 1 mol NaOH (or 1 mol e ) thus, 1 equiv = 1 mol. (In its reactions to produce oxyanions of chlorine (C10 , C102, etc.), there is more than 1 equivalent per mole.)... 

Copper complexes are most ffeqnently prepared by oxidation of Cu and Cu complexes, initially accomplished with various chemical oxidizing agents, including aqueous hypochlorite (C10 ), chlorine or flnorine gas, alkaline persulfate [(S20g) ] solutions, and oxidizing oxyanions such as TeOe and Thus, this is how the pale-green... 

The reactivity of 02 - with alkyl halides in aprotic solvents occurs via nucleophilic substitution. Kinetic studies confirm that the reaction order is primary > secondary > tertiary and I > Br > Cl > F for alkyl hahdes, and that the attack by 02 - results in inversion of configuration (Sn2). Superoxide ion also reacts with CCI4, Br(CH2)2Br, CeCle, and esters in aprotic media. The reactions are via nucleophilic attack by 02 on carbon, or on chlorine with a concerted reductive displacement of chloride ion or alkoxide ion. As with all oxyanions, water suppresses the nucleophilicity of 02 (hydration energy, lOOkcalmoL ) and promotes its rapid hydrolysis and disproportionation. The reaction pathways for these compounds produce peroxy radical and peroxide ion intermediates (ROO and ROO ). 

The relative rates of reaction between esters and oxyanions (HOO" (4.5) > 02 - (1.0) > HO (MeOH) (0.2)) are similar to those for CeCl, which indicates that both substrates undergo an initial nucleophihc addition to an unsaturated carbon (carbonyl and aryl chlorine, respectively). When a suitable leaving group is present, there is a net nucleophilic substitution. 

There are two possible condensation reactions for the nitrile. One is nucleophilic reaction of the oxyanion with the carbon of the nitrile functional group. This carbon is activated by nitrogen and by the strongly electron-withdrawing trichloromethyl group. The other possibility, 8 2 displacement of chloride, is ruled out because there are three chlorines and four bonds in the product. After the nucleophilic reaction, a trace of methanol is needed to form a neutral product by protonation of the anion. 

Chlorine in group 7A, the halogens, forms four oxyanions. These oxyan-ions are named according to the number of oxygen atoms present. The following conventions are used to name these oxyanions. 

Other halogens form oxyanions that are named similarly to the oxyanions chlorine forms. Bromine forms Br03, the hromate ion. Iodine forms the periodate ion (104 ) and the iodate ion (IO3 ). 

The next two series of nonmetals, silicon through chlorine and germanium through krypton, show a maximum coordination number of. six in hexafluoro anions., SF . and TcF. Even here the oxyacids and oxyanions typically. show a coordination... 

POr and PFe, the sulphur, chlorine, silicon, and aluminium analogues have been treated. New ab initio calculations have been reported on P04-,492 and data from X-ray emission and p.e.s. for several second-row oxyanions, including PO3-, give good agreement with the results of such computations.493... 

This mediated (S+X I+)-synthesis model is supported by the following evidence (i) the cationic silica species which are present at pH < 2 (ii) the near 1 1 surfactant-to-chlorine ratio in the hexagonal and lamellar products (iii) the easy removal of the surfactant with ethanol (iv) the observation that TEOS and SiC L hydrolyse and form mesophase products, while Cab-O-Sil, which does not readily hydrolyse in acidic conditions, forms no mesophase products and (v) the anion dependence of the synthesis, e.g., the different products obtained with Cl, Br, and oxyanions. 

The parent compound is so reactive towards thiols that up to four sulfur groups can be introduced. In isopropanol at — 10°C, however, the monosuhstituted compounds (109) (Nu = PhS) can be made in reasonable yield. Further nucleophilic substitution of 5-nitro and 5-phenylsulfonyl derivatives occurs at the 4- and 6-positions the 1,3-dihydro products are isolated <92JCS(PI)685>. Conditions have been devised for substitution of one or two chlorines in 5,6-dichloro-2Ff-benzimidazoles using amines, thiolate, or oxyanionic nucleophiles in ethanol <88S87i>. Indeed nucleophilic displacements of hydrogen are not uncommon (Scheme 57) <90HCA902>. 

For example, SO3 juimv cma oxyanions make up a series, hypo- (less than) and per- (more than) are used as prefixes to name the members of the series with the fewest and the most oxygen atoms, respectively. The best example involves the oxyanions containing chlorine ... 

The application of rule 2 can be seen in the names of the acids of the oxyanions of chlorine, as shown below. 

Which oxyanion of chlorine contains the most oxygen atoms hypochlorite, chlorite, or perchlorate ... 

Note in Table 2.5 that several series of anions contain an atom of a given element and different numbers of oxygen atoms. These anions are called oxyanions. When there are two members in such a series, the name of the one with the smaller number of oxygen atoms ends in -ite and the name of the one with the larger number ends in -ate—for example, sulfite (SO/ ) and sulfate (S04 ). When more than two oxyanions make up a series, hypo- (less than) and per- (more than) are used as prefixes to name the members of the series with the fewest and the most oxygen atoms, respectively. The best example involves the oxyanions containing chlorine, as shown in Table 2.5. 

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