Chlorine solution reactions

In the reaction of aEyl alcohol with an aqueous chlorine solution, addition of hypochlorous acid to the double bond of aEyl alcohol yields glycerol monochlorohydrin and as a by-product, glycerol dichlorohydrin. Thus, a poor yield of glycerol monochlorohydrin is obtained (8). To improve the yield of glycerol monochlorohydrin, addition of sodium carbonate in an amount equivalent to that of the hydrogen chloride in the aqueous chlorine solution, has been proposed (9). 

Uses. AEyl chloride is industrially the most important aHyl compound among all the aHyl compounds (see Chlorocarbons and CHLOROHYDROCARBONS, ALLYL CHLORIDE). It is used mosdy as an intermediate compound for producing epichlorohydrin, which is consumed as a raw material for epoxy resins (qv). World production of AC is approximately 700,000 tons per year, the same as that of epichlorohydrin. Epichlorohydrin is produced in two steps reaction of AC with an aqueous chlorine solution to yield dichloropropanol (mixture of 1,3-dichloropropanol and 2,3-dichloropropanol) by chlorohydrination, and then saponification with a calcium hydroxide slurry to yield epichlorohydrin. 

Chlorine dioxide gas is a strong oxidizer. The standard reversible potential is determined by the specific reaction chemistry. The standard potential for gaseous CIO2 in aqueous solution reactions where a chloride ion is the product is —1.511 V, but the potential can vary as a function of pH and concentration (26) ... 

The pH of the chlorine dioxide reaction mixture must be maintained in the 2.8—3.2 pH range, otherwise decreased conversion yields of chlorite to chlorine dioxide are obtained with by-product formation of chlorate. Generator efficiencies of 93% and higher have been demonstrated. A disadvantage of this system is the limited storage life of the sodium hypochlorite oxidant solution. 

A major disadvantage of this system is the limitation of the single-pass gas-chlorination phase. Unless increased pressure is used, this equipment is unable to achieve higher concentrations of chlorine as an aid to a more complete and controllable reaction with the chlorite ion. The French have developed a variation of this process using a multiple-pass enrichment loop on the chlorinator to achieve a much higher concentration of chlorine and thereby quickly attain the optimum pH for maximum conversion to chlorine dioxide. By using a multiple-pass recirculation system, the chlorine solution concentrates to a level of 5-6 g/1. At this concentration, the pH of the solution reduces to 3.0 and thereby provides the low pH level necessary for efficient chlorine dioxide production. A single pass results in a chlorine concentration in water of about 1 g/1, which produces a pH of 4 to 5. If sodium chlorite solution is added at this pH, only about 60 percent yield of chlorine dioxide is achieved. The remainder is unreacted chlorine (in solution) and... 

The generation of PPV and corresponding derivatives via the dihalide approach is possible not only in solution reaction, but also - via the gas phase -in a so-called chemical vapor deposition (CVD) process. In this process, the vapor of a dichlorinated para-xylene (a,a or a,a) is pyrolyzed at moderately low pressures (0,1-0,2 torr) to form a chlorinated para-xylylene intermediate, which then condenses and polymerizes on a suitable, cooled substrate. The coating of the chlorinated precursor polymer can be heated to eliminate HCl, to form PPV 60 (or a PPV derivative) [88]... 

The propene is finally treated with chlorine solution and it undergoes an addition reaction to form the desired product, 1,2-dichloropropane. 

Isopropylidine adenosine was converted to the p-toluene sulphonyl (tosyl) ester by reaction with tosyl chlorine solution, following the method of Clark et al. (1951) [J. Chem. Soc. 2952]. Because of its tendency to cyclization, the reagent was used directly it was ready. A reaction flask with separating funnels was set up in such a way that the whole system could be evacuated and filled with pure nitrogen two or three times, to eliminate all oxygen, and reagents could then be added when desired, in the closed system. 

The multiple chlorination of another activated compound, phenoxyacetic acid, leads to a useful product. This compound is made industrially by an S>j2 reaction (Chapter 17) on chloroacetic acid (made by chlorination of acetic acid, Chapter 21) with phenol in alkaline solution. Reaction occurs at the oxygen atom rather than on the ring. 

A chlorine solution is prepared by bubbling chlorine gas into ice-cold water. This solution is added to wood meal or wood slices in a small glass-stoppered Erlenmeyer flask. After 10min, the solution is discarded and the sample is rinsed twice with water. On subsequent treatment with 4% sodium sulfite solution, color appears which is similar to that observed in the Maule reaction,... 

The [RhClJ2- ion is very reactive in solution, and rapidly oxidizes coordinated chlorides to chlorine this reaction has not been thoroughly studied, but 85-88% of the anticipated Cl, has been recovered, and the Rh-containing product is presumably an aquachlororhodium(III) anion.1238 Attempts to prepare salts other than cesium have not been successful,1237 presumably because of the rapid internal redox reaction which occurs in solution the rapid precipitation of the insoluble Cs salt lessens this contamination. 

It is now recognized that anomalously low Tafel slopes can be observed for the chlorine evolution reaction due to rate-limiting transport of gas away from the electrode surface [471, 474], e.g. in concentrated chloride solutions at high temperatures. 

Aliphatic nitroso compounds can be prepared from IV-alkylhydioxylamines oxidation widi bromine, chlorine or sodium hypochlorite in weakly acidic solution, reaction with potassium dichromate in acetic or sulfuric acid, and by oxidation widi yellow mercury(II) oxide in suspension in an organic solvent. Silver carbonate on Celite has also been used to prepare aliphatic nitroso compounds, such as ni-trosocyclohexane, in high yield from the corresponding hydroxylamines." Aqueous sodium periodate and tetraalkylanunonium periodates, which are soluble in organic solvents, are the reagents most commonly used for the oxidation of hydroxamic acids and IV-acylhydroxylamines to acylnitroso compounds... 

The possibility of using brine to slurry the ore in the presence of an oxidizer such as chlorine in order to extract metals from the more common sulfide minerals has been studied by Strickland and co-workers (Jl, S12, S13). The reactions of acid chlorine solutions with galena (PbS), pyrite (FeSj), sphalerite (ZnS), chalcocite (CujS), covellite (CuS), chalcopyrite (CuFeSs), bornite (CusFeSi), pyrrhotite (FeS), and arsenopyrite (FeAsS) were examined with respect to their reaction rates and mechanisms. 

Alkanes and arenes can also be activated to other reactions by platinum complexes in aqueous solution (57,58). For arenes in the presence of H2PtCl5, reduction from Pt(IV) to Pt(II) occurs and the arene undergoes chlorination. The reaction is catalyzed by platinum(II) (59). Similarly, if a platinum(IV) catalyst such as HjPtClg is used, chloroalkanes are formed from alkanes. As an example, chloromethane is formed from methane (Eq. 23) (60-62). Linear alkanes preferentially substitute at the methyl... 

Several reviews addressing the polarization behavior, d ion adsorption, competition between Cr adsorption and OH codeposition, oxide film formation, and cr ion discharge, as well as the kinetic aspects of the reaction on various oxide-covered and oxide-free surfaces that have been investigated during the past 15 years, have been published (55/, 333-338). Of these, particular mention should be made of Refs. 555, 335, 336, and 439-441, where the basic aspects of the properties of oxide electrodes and the kinetic aspects of oxide film formation in relation to Cl adsorption and the kinetics of Cr ion discharge were addressed. Mechanistic aspects of chlorine evolution were critically analyzed recently in an excellent article by Trasatti (338). In this article, the focus is primarily on the nature and characterization of the adsorbed intermediates partipatingin the course of CI2 evolution and their role in the electrocatalysis of the chlorine evolution reaction. As with the OER, in aqueous solutions CI2 evolution takes place on an oxidized surface of metals or on bulk oxide films, so that their surface states often have to be considered in treating the electrocatalysis of the reaction. 

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