Reversion dextrin

The reverse flotation method. It was examined by several Russian scientists. This method involves depression of smithsonite using sodium phosphate and dextrin. Calcite and dolomite are floated using oleic acid in stage additions. The tailings become the zinc concentrate. 

The 3 + 2-cycloaddition of nitrile oxides to 2-crotyl-l,3-dithiane 1-oxides produces exclusively 5-acyldihydroisoxazoles.92 Lewis acid addition to 1,3-dipole cycloaddition reactions of mesityl nitrile oxide with a, / -unsaturated 2-acyl-1,3-dithiane 1-oxides can reverse the sense of induced stereoselectivity.93 The 1,3-dipolar cycloaddition of 4-t-butylbenzonitrile oxide with 6A - aery lamido - 6A - dc o x y - [> - c y c I o dextrin (68) in aqueous solution favours the formation of the 4-substituted isoxazoline (69) rather than the 5-substituted regioisomer (Scheme 24).94 Tandem intramolecular cycloadditions of silyl nitronate, synthons of nitrile oxides, yield functionalized hydrofurans.95... 

Figure 15. Rate of the debranching enzyme on phosphorylase limit dextrin in the presence of the irreversible inhibitor dimethyiarsenothioglucose in the presence and absence of a reversible inhibitor (Bis-Tris). Adapted from Gillard et al.

In normal polysaccharide HPLC, the most polar molecules with identical M are the last to elute in a polar solvent, because of their greater interaction with the aqueous stationary phase. Reverse-phase HPLC is the technique of substituting the LPLC stationary phase with a nonpolar solvent stationary phase and using a less polar mobile phase, with the result that the most polar homologs elute first. Heyraud and Rinaudo (1991) applied reverse-phase HPLC to the separation of low DP anomeric dextrins and Voragen et al. (1982) applied it to analysis of pectin enzyme digests. 

Cyclodextrins are water-soluble hosts for hydrophobic guests. The formation of inclusion complexes is controlled by the dimensional compatibility of the guest and host cavity. Commercially available dextrins are, in fact, inclusion complexes of cyclodextrins with two water molecules closing the entrance to the cavity. The formation of cyclodextrin inclusion complexes is reversible and, therefore, is governed by concentration of guests competing for a place inside the cavity. 

Some of the properties of dextrins may be easily and effectively modified. One of them is the solubility of dextrins. The hydrolysis of dextrins in the presence of a reversed micelle has been carried out as a part of model studies on the depolymerization of polysaccharides, and of poly- as well as oligo-saccharide waste, for the manufacture of ethanol and livestock feed. It was found that dextrin may be readily hydrolyzed in benzene by means of... 

The problem of solvation of dextrins is still unsolved in general. It was documented that even such commonly used solvents as ethanol exhibit an unusually strong interaction with dextrin, as determined by H-n.m.r. spectroscopy. The interaction of dextrin with normal alcohols from methanol to 1 -hexanol was studied by determination of their infinite-dilution activity-coefficients in dextrin - water mixtures. " Studies carried out on the adsorption of dextrin on oxidized coal revealed that hydrophobic moieties in dextrin are involved in that process. The possibility of hydrophobic bonding has made dextrin an interesting component of the media used for flotation. Dextrin acts as a flocculant (depressant). When combined with a proper additive providing action by means of hydrogen bonding, reverse flotation... 

One difficulty with the unsymmetrical, [Pg.424]

Quartz Fatty acids, a mitres Fatly acids, amines Stanch, dextrin Flotation of bemetite using fatty acids around anutral pH and reverse flotation of quartz using amines Easily flotable in tbe acidic range calcite is usually present as ihe gargue in other salt-type minerals... 

In recent years, fatty amines have been used as the collector of quartz in the reverse flotation of hematite in laboratory and industry. For example, using starch and dextrine as depressant, the flotation results of Canadian Knob iron ore using various amine collectors in laboratory can be given as follows ... 

Dextran-Dextrinase. A dextran-forming enzyme from Acetobacter cap-sularum converts a-1,4 linkages to a-1,6, but acts only on substrates of intermediate size. This dextran-dextrinase catalyzes a reversible reaction in which the terminal residue of either a dextrin (a-1,4) or a dextran (a-1,6) is transferred to the other polysaccharide. ... 

The principal dextrins formed contain either 6 or 7 D-glucopyranose units linked in a ring (see above under Starch). In the presence of suitable cosubstrates such as D-glucose, D-maltose, and sucrose, the reaction reverses to produce linear polysaccharides 176), The macerans enzyme is similar in action to the Q-enzyme in that blocks of D-glucose units are transferred in contrast to individual D-glucose units. 

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