Acetate, active oxidation

The action of lead tetraacetate on osazones of Cw-labeled sugars in warm aqueous acetic acid has been employed46 for determining specific activity of the oxidizable carbon atoms present, that is, C4, C5, and C6 of D-glucose phenylosotriazole. In the potassium acetate-catalyzed oxidation, D-glucos-azone (o-arabino-hexose phenylosazone) yielded two moles of formic acid... 

SULFOX BH is activated by acid (typically 84% acetic acid) and heat to form powerful, synergetically active oxidizing species which rapidly convert the leuco (reduced) sulfur or vat dye to the stable )ceto (oxidized) form. 

Quite analogously to the olefin oxidation in aqueous medium, acetoxylation of olefins can also be carried out catalytically by addition of oxidants such as ben-zoquinone [1], cupric chloride, and cupric acetate (a survey of the patent literature has been given by Krekeler and Schmitz [19] and Miller [20]) which oxidize the metallic palladium to the active oxidation state Pd (eq. (2)). Cuprous chloride is reoxidized by oxygen (eq. (3)) and the overall reaction according to eq. (4) becomes catalytic. 

Fig. 2 Reactions at the hydroxyl groups of glycosyl residues of oligo-/polysaccharides. (A) Basic a(l 4) linked glycosyl residue. (B) Oxidation at C6 position to form uronic acid. (C) Oxidation/substitution at C2 position to form acetate. (D) Oxidation/ substitution at C2 position to form glucosyl-2-amine. (E) Oxidation/substitution/compatibilization at C2 position to form glucosyl-2-A-acetyl. (F) Oxidation/substitution/compatibilization at C4 position compatibilization glycosyl-4-sulfate. (G) Oxidation/activation at C6 position compatibilization glucosyl-6-phosphate. (Molecular modeling SWEET, http //www.dkfz-heidelberg.de/spec/sweet2/doc/index.php. Chemistry MDL ISIS/draw.) (View this art in color at www.dekker.com.)...

The activation parameters (Table 3) are characterized by positive values of H koA negative values of and indicate that bond-formation plays an important role in forming the transition state. This is in agreement with previous work which showed that oxidative addition proceeds via an associative mechanism." For 2 in ethyl acetate, the oxidative addition rate constants could not be determined accurately, but /cr could be used for the calculation of the activation parameters. The values suggest less ordered transition states in which significant solvent interaction may occur, but it is clear that additional research is still required. 

Application of 2.4-pentanediol (PD) and its homoloeues for new diastereo-differentiatinv reactions as chiral auxiliaries-. In the early 80 s, optically pure PD prepared by our siiiqile procedures became available in a practical scale and various types of use were proposed shortly thereafter. One of the most extensively studied uses is as a chiral auxiliary built in the prochiral ketone or aldehyde as an acetal. The diastereo-differentiating attacks of various nucleophiles on the PD acetals activated by the Lewis acid, proceeds effectively giving the PD mono-ether of chiral alcohols in 80-95 % d.e. After the reaction, removing the PD unit from the mono-ether can easily be carried out by oxidation of the hydroxy group and mild base treatment. Because of good d.e. s. of the... 

CHLORURE PERRIQUE (French) (7705-08-0) Very hygroscopic contact with moisture in air forms ferric chloride hexahydrate. Aqueous solution is highly acidic, precipitating hydroxide and phosphate salts, and forming corrosive fumes. Violent reaction with strong bases, allyl chloride, bromine pentafluoride, ethylene oxide, oxygen difluoride. Shock- and friction-sensitive explosive is formed with potassium, sodium, potassium-sodium aUoy, and possibly with other active metals. Aqueous solution is incompatible with sulfuric acid, caustics, ammonia, aliphatic amines, alkanolamines, amides, organic anhydrides, isocyanates, vinyl acetate, alkylene oxides, epichlorohydrin. Attacks metals in the presence of moisture. 

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