Peroxodisulfates

In addition to CuCfi, some other compounds such as Cu(OAc)2, Cu(N03)2-FeCl.i, dichromate, HNO3, potassium peroxodisulfate, and Mn02 are used as oxidants of Pd(0). Also heteropoly acid salts comtaining P, Mo, V, Si, and Ge are used with PdS04 as the redox system[2]. Organic oxidants such as benzo-quinone (BQ), hydrogen peroxide and some organic peroxides are used for oxidation. Alkyl nitrites are unique oxidants which are used in some industrial... 

Acetoxybenzene is prepared by the reaction of benzene with Pd(OAc)2[325,342-345], This reaction is regarded as a potentially useful method for phenol production from benzene, if carried out with only a catalytic amount of Pd(OAc)2. Extensive studies have been carried out on this reaction in order to achieve a high catalytic turnover. In addition to oxygen and Cu(II) salts, other oxidants, such as HNOi, nitrate[346,347], potassium peroxodisulfate[348], and heteropoly acids[349,3S0], are used. HNO is said to... 

Benzoic acid and naphthoic acid are formed by the oxidative carbonylation by use of Pd(OAc)2 in AcOH. t-Bu02H and allyl chloride are used as reoxidants. Addition of phenanthroline gives a favorable effect[360], Furan and thiophene are also carbonylated selectively at the 2-position[361,362]. fndole-3-carboxylic acid is prepared by the carboxylation of 1-acetylindole using Pd(OAc)2 and peroxodisulfate (Na2S208)[362aj. Benzoic acid derivatives are obtained by the reaction of benzene derivatives with sodium palladium mal-onate in refluxing AcOH[363]. 

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

Peroxodisulfates. The salts of peroxodisulfuric acid are commonly called persulfates, three of which are made on a commercial scale ammonium peroxodisulfate [7727-54-0] (NH4)2S20g potassium peroxodisulfate [7727-21-1] K2S20g and sodium peroxodisulfate [7775-27-1] Na2S20g. The peroxodisulfates are all colorless, crystalline soHds, stable under dry conditions at ambient temperature but unstable above 60°C. 

The peroxodisulfate ion in aqueous solution is one of the strongest oxidising agents known. The standard oxidation—reduction potential for the following reaction is 2.08 V (77,78). 

Reactions involving the peroxodisulfate ion are usually slow at ca 20°C. The peroxodisulfate ion decomposes into free radicals, which are initiators for numerous chain reactions. These radicals act either thermally or by electron transfer with transition-metal ions or reducing agents (79). 

The principal use of the peroxodisulfate salts is as initiators (qv) for olefin polymerisation in aqueous systems, particularly for the manufacture of polyacrylonitrile and its copolymers (see Acrylonitrile polymers). These salts are used in the emulsion polymerisation of vinyl chloride, styrene—butadiene, vinyl acetate, neoprene, and acryhc esters (see Acrylic ester polymers Styrene Vinyl polymers). 

An expanding development is the use of peroxodisulfates as oxidants in organic chemistry (80,81). These reactions are initiated by heat, light, gamma rays, or transition-metal ions. The primary oxidising species is usually the sulfate ion radical, P hskip -3pt peroxodisulfate anion... 

The three peroxodisulfates are ah. toxic and irritating to skin, eyes, and mucous membranes. Pubhshed toxicity studies are as foUow (28) ... 

The LD q value for sodium peroxodisulfate using iv adininistration in rabbits is 178 mg/kg. 

The peroxodisulfates are made commercially by Akkim (Turkey), Degussa (Germany), PMC, Migas, Peroxid-Chemie, ERB Engineering (India), Sangen (Taiwan), and TokaiDenka (Japan). In 1994 the U.S. price of the sodium salt was 1.92/kg, the potassium salt 2.07/kg, and the ammonium salt 1.68/kg. 

Because the peroxodisulfate salts are all made electrochemicaHy, the electrical energy cost is a significant part of thek manufacturing cost. The 1994 world capacity for peroxodisulfate salts was about 75,000 metric tons, valued at about 30 x 10 . The principal appHcations are in polymerization catalysis and the market broadly tracks the plastics business. The Caro s acid business is difficult to quantify because the product itself is not commercial but made on-site from purchased hydrogen peroxide. 

Beaded acrylamide resins (28) are generally produced by w/o inverse-suspension polymerization. This involves the dispersion of an aqueous solution of the monomer and an initiator (e.g., ammonium peroxodisulfates) with a droplet stabilizer such as carboxymethylcellulose or cellulose acetate butyrate in an immiscible liquid (the oil phase), such as 1,2-dichloroethane, toluene, or a liquid paraffin. A polymerization catalyst, usually tetramethylethylenediamine, may also be added to the monomer mixture. The polymerization of beaded acrylamide resin is carried out at relatively low temperatures (20-50°C), and the polymerization is complete within a relatively short period (1-5 hr). The polymerization of most acrylamides proceeds at a substantially faster rate than that of styrene in o/w suspension polymerization. The problem with droplet coagulation during the synthesis of beaded polyacrylamide by w/o suspension polymerization is usually less critical than that with a styrene-based resin. 

Hydrogen peroxide was first made in 1818 by J. L. Thenard who acidified barium peroxide (p. 121) and then removed excess H2O by evaporation under reduced pressure. Later the compound was prepared by hydrolysis of peroxodisulfates obtained by electrolytic oxidation of acidified sulfate solutions at high current densities ... 

Peroxodisulfuric acid, H2S2O8, is a colourless solid mp 65° (with decomposition). The acid is soluble in water in all proportions and its most important salts, (NH4)2S208 and K2S2O8, are also freely soluble. These salts are, in fact, easier to prepare than the acid and both are made on an industrial scale by anodic oxidation of the corresponding sulfates under carefully controlled conditions (high current density, T < 30°, bright Pt electrodes, protected cathode). The structure of the peroxo-disulfate ion [now preferably called hexaoxo-/r-peroxodisulfate(2-)]0 l is OaSOOSOa " with... 

Aqueous ceric solutions are widely used as oxidants in quantitative analysis they can be prepared by the oxidation of Ce ( cerous ) solutions with strong oxidizing agents such as peroxodisulfate, S20g ", or bismuthate, BiOg". Complexation and hydrolysis combine to render (Ce" +/Ce +) markedly dependent on anion and acid concentration. In relatively strong perchloric acid the aquo ion is present but in other acids coordination of the anion is likely. Also, if the pH is increased, hydrolysis to... 

Oxidation of 2-mercapto-l,2,4-triazolo[l,5-c]pyrimidines (174) with chlorine or bromine in water (64BRP951652 65JCS3369), with hydrogen peroxide and chlorine (95MIP1), as well as with sodium chlorate in hydrochloric acid (94JMC2371) gave the corresponding 2-sulfonyl halide derivatives 175. Oxidation of the 2-alkylmercapto compounds 176 to the 2-alkylsufonyl derivatives 177 was made with ammonium peroxodisulfate and sulfuric acid... 

The hydroxylation of a phenol 1 upon treatment with a peroxodisulfate in alkaline solution, to yield a 1,2- or 1,4-dihydroxybenzene 3, is called the Elbs reaction The phenol is deprotonated by base to give a phenolate anion 4, that is stabilized by resonance, and which is activated at the ortho or the para position towards reaction with an electrophilic agent ... 

Reaction with the electrophilic peroxodisulfate occurs preferentially at the para position, leading to formation of a cyclohexadienone derivative 5, which loses a proton to give the aromatic compound 6. Subsequent hydrolysis of the sulfate 6 yields 1,4-dihydroxybenzene 3 ... 

Also, friction has caused the expin of an NH4 peroxodisulfate/Na202 mixt (Ref 8). Spont ign has occurred upon mixt or contact of Na202 at RT with mats such-as moist cloth, paper or wood (Refs 3 16) H2S or various peroxides (Ref 8) C02 or metallic Na (Refs 6 9) non-metal halides (Refs 8 9) org liqs (benz, eth, aniline, etc) and w (Ref 3) and AgCl and charcoal (Ref 7). Percussion has caused spont ign of mixts of various org mats with NaOH or KOH and Na202 (Ref 17). Percussion has also caused spont ign to occur when Na202 is mixed with mats such as hay, bark, cotton or powd S (Ref 17). When Na and Na202 were heated together to the mp of Na (97.7°) under Ar, expl ign has also occurred (Ref 15)... 

Ammonium Peroxodisulfate, HgNjOgS A mixt with A1 and W may explode H.A.J. Pieters et al, Safety In The Chemical Laboratory , Academic Press, London (1957)... 

Calcium Peroxodisulfate, CaOgS2 Sensitive to shock explodes violently H.M. Castrantas et al, Laboratory Handling and Storage of Peroxy Compounds , ASTM Spec Pub No 491, Phila (1970)... 

Chain mechanism. The reaction between formic acid and peroxodisulfate ions is... 

Dipping solution Dissolve 1 g potassium peroxodisulfate and 34 mg silver nitrate in 60 ml water and make up to 100 ml with acetone [5]. 

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