Sodium chlorite, oxidation

Sodium chlorite oxidation of com and rice starches is recommended for the production of textile sizes (101) and oxidized starch is recommended as a hardening agent in the immobilization of microbial cells within gelatin (102). 

N-Methylated y-amino-p-hydroxy acids are accessible by the usual synthetic sequences, i.e. aldol condensation or y-amino-P-oxo ester reduction, starting from the corresponding N-methylated a-amino acids, but are obtained with low diastereoselectivity. 61-63 Alternatively, Brown allylboration of the ALBoc-ALMe amino aldehyde 16 (R1 = Bzl, X=Boc, Y = Me) gives the allyhc N-methylated intermediate 27 in 64% yield and 90% de (Scheme 12). 64 Oxidative cleavage of the alkenol is performed using the two-step ozonolysis and sodium chlorite oxidation sequence. 

The closing stages of Carreira s synthesis of (+ )-zaragozic acid C (Scheme 7.4) began with the Dess-Martin oxidation6 of 18. An ozon-olysis next yielded trialdehyde 19, and a buffered sodium chlorite oxidation provided the corresponding triacid. Of particular interest here was... 

Fig. 17.17. Sodium chlorite oxidation of aliphatic or aromatic aldehydes to form a carboxylic acid. The extra additive destroys the reduction product of the oxidant, i.e., sodium hypochlorite or hypochloric acid.

Again, a chromium-free oxidation method is employed. Sodium chlorite oxidizes aliphatic or aromatic aldehydes. In the process it forms hypochloric acid (HOCl) or sodium hypochlorite (NaOCl), which are even more reactive than sodium chlorite and therefore must be quenched in situ by the olefinic additive 2-methyl-2-butene in an acidic buffer medium. 

By examination of the spectra in Figure 5, it is clear that polysaccharides (holocellulose, peaks at 72 and 106 ppm) are dominant in the delignified humin in the upper layers of peat but diminish in relative concentration with depth. This trend was also observed in the spectra of humin in Figure 2. At depth, the polysaccharides are minor compared to the paraffinic carbons (peak at 30 ppm). Thus, the paraffinic structures in humin are resistant to sodium chlorite oxidation, and their relative increase in concentration with... 

Many of the metal chlorites are not particularly stable and will explode or detonate when stmck or heated. These include the salts of Hg", Tl", Pb ", Cu", and Ag". Extremely fast decomposition with high heat evolution has been noted for barium chlorite [14674-74-9] Ba(Cl02)2, at 190°C, silver chlorite [7783-91-7] AgC102, at 120°C, and lead chlorite [13453-57-17, at 103°C (109). Sodium chlorite can be oxidized by ozone to form chlorine dioxide under acidic conditions (110) ... 

Sodium chlorite is used to produce chlorine dioxide by chemical oxidation, electrochemical oxidation methods, or by acidification with acids. Most of the commercial methods employ chlorine or sodium hypochlorite. 

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. 

Electrochemical Generation of Chlorine Dioxide from Chlorite. The electrochemical oxidation of sodium chlorite is an old, but not weU-known method of generating chlorine dioxide. Concentrated aqueous sodium chlorite, with or without added conductive salts, is oxidized at the anode of an electrolytic cell having a porous diaphragm-type separator between the anode and cathode compartments (122—127). The anodic reaction is... 

Mechanisms in Chlorine Dioxide Generation from Chlorite. The reactions between sodium chlorite and chloriue-based oxidizers and acids are complex and involve the formation of the proposed unsymmetrical intermediate, [CI2O2] (16,18,22,36,108,135—140). 

Organic Reactions. The chlorite ion, CIO,, is mosdy a weak and slow oxidizer in alkaline aqueous solutions. Aldehydes (qv) can be readily oxidized to the corresponding carboxyhc acids in neutral or weakly acidic solutions. Mixing sohd sodium chlorite with combustible organic materials can result in explosions and fire on shock, exposure to heat, or dames. 

Sodium chlorite is not Hsted by the USEPA or any regulatory authority as a carcinogen. Studies conducted ia mice and rats did not show an increase in tumors in animals exposed to sodium chlorite in thek drinking water. Sodium chlorite has been found to have mutagenic activity in some in vitro test systems such as the Ames Salmonella reverse mutation assay without the presence of metaboHc activators. The significance of these test results in regard to human health is not clear because of the oxidizing effects of the chlorite ion (149). 

Industrial Processes. The use of sodium chlorite as an oxidizer in NO and SO combustion flue gas scmbber systems has been described... 

Sodium chlorite has also been used for treatment and removal of toxic and odorous gases such as hydrogen sulfide and mercaptans. Chlorine dioxide from chlorite is also useful for microbial and slime control in paper mills and alkaline paper machine systems (164,165). The use of sodium chlorite in textile bleaching and stripping is well known. Cotton is not degraded by sodium chlorite because the oxidation reactions are specific for the hemiceUulose and lignin components of the fibers. 

Appropriate pyrido[2,3-d]pyrimidin-5-ones with formyl groups in the 6-position have been oxiized to piromidic (68) and pipemidic (69) acids, or to intermediates for these, using moist silver oxide, chromium trioxide (potassium dichromate), potassium permanganate or, alternatively, sodium chlorite/hydroxylamine-O-sulfonic acid. 6-Acetyl groups have been similarly oxidized using sodium hypobromite in aqueous dioxane, whilst 2-acetyl groups give dimethylaminomethylene derivatives en route to 2-pyrazolylpyrido[2,3-d]pyrimidines. 

Chlorine dioxide, discovered in 1811 by Davy, was prepared from the reaction of potassium chlorate with hydrochloric acid. Early experimentation showed that chlorine dioxide exhibited strong oxidizing and bleaching properties. In the 1930s, the Mathieson Alkali Works developed the first commercial process for preparing chlorine dioxide from sodium chlorate. By 1939, sodium chlorite was established as a commercial product for the generation of chlorine dioxide. 

Hypophosphoric acid, (H0)2P(0)-P(0)(0H)2, is usually prepared by the controlled oxidation of red P with sodium chlorite solution at room temperature the tetrasodium salt, Na4P2O6.10H2O, crystallizes at pH 10 and the disodium salt at pH 5.2 ... 

Chlorine oxidation of sodium chlorite has also been used on both an industrial scale (by mixing concentrated aqueous solutions) or on a laboratory scale (by passing CVair through a column packed with the solid chlorite) ... 

Sn2 addition 413 Sn2 displacement 215 Sn2 lactone opening 412 ff. sodium bis(2-methoxyethoxy)-aluminium hydride see Red-Al sodium chlorite 516 - oxidation 772 sodium hypochlorite 550 f. sodium naphthalenide 739 f. sodium trimethoxyborohydride 390 SOMO 409... 

OXIDATION OF PRIMARY ALCOHOLS TO CARBOXYLIC ACIDS WITH SODIUM CHLORITE CATALYZED BY TEMPO AND BLEACH 4-METHOXYPHENYLACETIC ACID... 

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