Hypochlorite anions

Conversion of Aromatic Rings to Nonaromatic Cyclic Structures. On treatment with oxidants such as chlorine, hypochlorite anion, chlorine dioxide, oxygen, hydrogen peroxide, and peroxy acids, the aromatic nuclei in lignin typically ate converted to o- and -quinoid stmctures and oxinane derivatives of quinols. Because of thein relatively high reactivity, these stmctures often appear as transient intermediates rather than as end products. Further reactions of the intermediates lead to the formation of catechol, hydroquinone, and mono- and dicarboxyhc acids. 

Solutions of available chlorine bleaches decompose on standing at a rate that depends on the conditions described below. Hypochlorous acid [7790-92-3] and hypochlorite anions decompose according to equations 6 and 7 (20,21) ... 

The value of x is three orders of magnitude smaller than 0.67, so the approximation is valid. We know that the hypochlorite anion is the conjugate base of hypochlorous acid, so a pH > 7 is a reasonable result. 

After completing our analysis of the effects of the dominant equilibrium, we may need to consider the effects of other equilibria. The calculation of [H3 O ] in a solution of weak base illustrates circumstances where this secondary consideration is necessary. Here, the dominant equilibrium does not include the species, H3 O, whose concentration we wish to know. In such cases, we must turn to an equilibrium expression that has the species of interest as a product. The reactants should be species that are involved in the dominant equilibrium, because the concentrations of these species are determined by the dominant equilibrium. We can use these concentrations as the initial concentrations for our calculations based on secondary equilibria. Look again at Example for another application of this idea. In that example, the dominant equilibrium is the reaction between hypochlorite anions and water molecules H2 0 l) + OCr(c2 q) HOCl((2 q) + OH ((2 q) Working with this equilibrium, we can determine the concentrations of OCl, HOCl, and OH. To find the concentration of hydronium ions, however, we must invoke a second equilibrium, the water equilibrium 2 H2 0(/) H3 O (a q) + OH (a q)... 

NaOCl Sodium hypochlorite is ionic, containing Na cations and OCl anions. The sodium cation has oxidation number equal to its charge, +1. In the anion, oxygen is -2 (Guideline 4), so chlorine must be +1 for the sum of the oxidation numbers to match the -1 charge of the hypochlorite anion (Guideline 2). 

Alpha-l-antiprotease (ai-AP) limits tissue damage arising from the actions of the leucocyte protease, elastase (Carrell and Travis, 1985), and there is much evidence available for the oxidative inactivation of this protein by oxygen-derived free-radical species and hypochlorous acid/hypochlorite anion (HOCl/OCP). The mechanism of this inactivation appears to involve the oxidation of a critical methionine residue (Met-358) to its corresponding sulphoxide and methionine sulphoxide has been detected in ai-AP samples isolated from the lungs of cigarette smokers (Carp et al., 1982) and rheumatoid synovial fluids (Wong and Travis, 1980). 

The mechanism of hypochlorite bleaching appears to be considerably less controversial than peroxide bleaching. The pH-related active species in sodium hypochlorite are shown in Figure 10.29 and Scheme 10.33. The pH range 9-11 is the most suitable for hypochlorite bleaching. The active bleaching species is the hypochlorite anion CIO. In fact bleaching... 

Secondary hydrogen kinetic isotope effects are further classified as alpha, beta, etc. depending on the distance of the isotopically substituted atom from the bond(s) that is (are) being made or broken (a = 1 bond, 3 = 2 bonds, etc.). Consider the simple Sn2 reaction between hypochlorite anion and ethyl chloride ... 

Fig. 10.6 Alternative pathways of reaction between hypochlorite anion and ethyl chloride (Villano, S. M., Kato, S. and Bierbaum, V. M., J. Am. Chem. Soc. 128, 736 (2006))...

There is some evidence suggesting that camosine can upregulate immune function. Camosine s ability to react with hypochlorite anions (Formazyuk et al, 1992 Quinn et al, 1992) generated in activated leukocytes via the myeloperoxidase reaction, suggests that the dipeptide may limit hypochlori te-med ia ted oxidation in vivo (Pattison and Davies, 2006)... 

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... 

Bleach, sodium hypochlorite, NaOCl. Bleach sold commercially is a dilute solution of sodium hypochlorite, NaOCl, usually 5% in concentration. The active agent is the hypochlorite anion. In solution, it behaves as if free chlorine, Cl2, were present. Chlorine is an effective oxidizing agent. Thus in the presence of iodide salts, such as potassium iodide, KI, iodide anions are oxidized to iodine, I2 chlorine is reduced to chloride anions, Cl . 

The prefixes hypo- and per- remain as part of the acid name. For example, the acid of the perchlorate anion, CIO4", is perchloric acid, HCIO4. The acid of the hypochlorite anion, CIO", is hypochlorous acid, HCIO. 

Hypochlorite is another effective bleaching compound at normal temperature. The use of liquid hypochlorite has gained importance in many countries where laundry habits, such as cold water washing, made the sodium perborate less effective. Hypochlorite reacts with an alkaline to produce hypochlorite anions [4, 18, 19]. 

In the case of strongly polluted surface water, chlorination is the first purification step and is carried out after removal of any coarse foreign matter. Sufficient chlorine is added to ensure a free chlorine concentration of ca. 0.2 to 0.5 mg/L in the water after treatment (break-point chlorination). Chlorine reacts with water forming hydrochloric acid and the hypochlorite anion, depending upon the pH. 

At a pH of 7.5, near neutral conditions, the hypochlorous acid will be roughly 50% dissociated and disinfection will still be quite effective. However, in disinfections of somewhat alkaline water supplies, the decreased hydrogen ion concentration will tend to depress the concentration of undissociated hypochlorous acid. At a pH of 10 or higher, hypochlorous acid would be present almost entirely (ca. 99.7%) as hypochlorite anion (e.g., see Section 15.5.2). This would substantially decrease the effectiveness of chlorine disinfection under these conditions [6], which could be remedied by pH adjustment of the supply before disinfection, by a higher chlorine dose rate, or by a longer contact time before water use. However, in practice, any source of supply above a pH of 8.5 would be adjusted to 8.5 before disinfection for other reasons. 

Oxidation of tetraethyl ethenylidenediphosphonate with aqueous NaOCl gives tetraethyl oxira-nylidene-l,l-diphosphonate directly via Michael P-addition of the hypochlorite anion followed by ring closure (Scheme 4.10). Preparation of the tetrasodium salt of the corresponding epoxide is accomplished in a two-step process through the bromohydrin. The latter is prepared from tetraethyl ethenylidenediphosphonate by treatment with Brj/HjO, followed by ring closure with a concentrated solution of NaOH. 5 ... 

The authors considered formation of compounds 9 and 10 to proceed by independent mechanisms. /V-Chloro compounds 9 are formed by attack of hypochlorite anion on the neutral indole molecule (8) according to an SEi mechanism, proceeding through formation of the cyclic intermediate 11 (Scheme 3). 

Hwang et al. [24] studied the Wittig reaction of benzyltriphenylphosphonium (BTPP) salts and benzaldehydes via ylide-mediated PTC. They concluded that the reaction of benzylidenetriphenyl phosphorane and the benzaldehyde in the organic phase is the decisive step for stereoselectivity. The order of effectiveness of substituents is CF3 > (Cl, Br) > MeO > F > NO2. Satrio and Doraiswamy [25] proposed a case study for the production of benzaldehyde in a possible industrial application of PTC. The reaction between benzyl chloride and hypochlorite anion is... 

A final point Is it reasonable to invoke un-ionized hypochlorous acid (HOCl) as an active intermediate in a solution of bleach, which is an alkahne medium With a pX of 7.53, hypochlorous acid is a weak acid, about three orders of magnitude weaker than acetic acid, so it s not an unreasonable proposal. On the other hand, it is possible to envision concerted pathways, such as the following, where the hypochlorite anion acts as the actual chlorinating agent ... 

Similarly oxidation of alcohols, amines, amides, sulfides, alkenes, etc., with aqueous sodium hypochlorite proceeds much better when performed under PTC conditions, despite that the hypochlorite anions transferred into the organic phase as TAA salts are rather unstable (eqs. 169-172). 

Hypochlorite is a well known oxidizing agent in the haloform reaction for the oxidation of methyl ketones to carboxylic acids. It has been shown that the hypochlorite anion can be transferred into organic solutions by PTC (quaternary cations). Some of the applications of this technique are given as follows (Scheme 91). 

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