Tartaric acid removal

The solution niay contain Pt,Ir and Au, contaminated with As, Sb and Sn. HC1 is added and the precipitated sulphides fused with Naa C03-f-Na3N03. Extraction with water removes As as soluble arsenate.The residue is reduced with Zn + HC1. Boiling with HC1 dissolves out the Sn. Again boiling with HN03 and tartaric acid removes Sb. The residue is heated to dull redness to render iridium insoluble. Dilated aqua regia is added. 

The purified commercial di-n-butyl d-tartrate, m.p. 22°, may be used. It may be prepared by using the procedure described under i o-propyl lactate (Section 111,102). Place a mixture of 75 g. of d-tartaric acid, 10 g. of Zeo-Karb 225/H, 110 g. (136 ml.) of redistilled n-butyl alcohol and 150 ml. of sodium-dried benzene in a 1-litre three-necked flask equipped with a mercury-sealed stirrer, a double surface condenser and an automatic water separator (see Fig. Ill, 126,1). Reflux the mixture with stirring for 10 hours about 21 ml. of water collect in the water separator. FUter off the ion-exchange resin at the pump and wash it with two 30-40 ml. portions of hot benzene. Wash the combined filtrate and washings with two 75 ml. portions of saturated sodium bicarbonate solution, followed by lOu ml. of water, and dry over anhydrous magnesium sulphate. Remove the benzene by distillation under reduced pressure (water pump) and finally distil the residue. Collect the di-n-butyl d-tartrate at 150°/1 5 mm. The yield is 90 g. 

Boil the tartaric acid and caustic soda solution for three hours in a round flask (I litre), or preferably in a tin bottle furnished with reflu. condenser. The use of a tin vessel obviates certain clitli-cultiesof filtration which the solution of the silica by the action of the alkali on the glass entails. The liquid, after boilinjg, is carefully neutralised with cone, hydrochloric acid (it is acl is-able to remove a little of the solution beforehand in case overshooting the mark) and an excess of calcium chloride solution is added to the hot liquid. The mixture is left overni hl. and the calcium salts filtered off at the pump, washed with water, and well pressed. 

Dithiol is a less selective reagent than thiocyanate for molybdenum. Tungsten interferes most seriously but does not do so in the presence of tartaric acid or citric acid (see Section 17.34). Tin does not interfere if the absorbance is read at 680 nm. Strong oxidants oxidise the reagent iron(III) salts should be reduced with potassium iodide solution and the liberated iodine removed with thiosulphate. 

The effect of different ions upon the titration is similar to that given under iron(III) (Section 17.57). Iron(III) interferes (small amounts may be precipitated with sodium fluoride solution) tin(IV) should be masked with 20 per cent aqueous tartaric acid solution. The procedure may be employed for the determination of copper in brass, bronze, and bell metal without any previous separations except the removal of insoluble lead sulphate when present. 

To minimize the decomposition of pigments, the nse of milder pigment extraction procedures has been proposed. This involves nsing weaker and volatile organic acids such as formic, acetic, citric, or tartaric acids or small amounts (0.01 to 3%) of stronger more volatile acids snch as trifluoroacetic acid, which could be then removed during pigment concentration. s concentrations on the order of 0.01 to 0.05% and... 

Methods for reducing peak absorption of americium after inhalation or oral exposure have not been described. Topical applications of saline containing DTP A, tartaric acid, or citric acid (e.g., Schubert s solution) have been used to remove americium from the skin and wounds after accidental dermal exposures (Breitenstein 1983). These agents form stable, water soluble complexes with americium. 

Reaction with chelating agents. Such reactions have been used primarily for partial dealumination of Y zeolites. In 1968, Kerr (8,21) reported the preparation of aluminum-deficient Y zeolites by extraction of aluminum from the framework with EDTA. Using this method, up to about 50 percent of the aluminum atoms was removed from the zeolite in the form of a water soluble chelate, without any appreciable loss in zeolite crystallinity. Later work (22) has shown that about 80 percent of framework aluminum can be removed with EDTA, while the zeolite maintains about 60 to 70 percent of its initial crystallinity. Beaumont and Barthomeuf (23-25) used acetylacetone and several amino-acid-derived chelating agents for the extraction of aluminum from Y zeolites. Dealumination of Y zeolites with tartaric acid has also been reported (26). A mechanism for the removal of framework aluminum by EDTA has been proposed by Kerr (8). It involves the hydrolysis of Si-O-Al bonds, similar to the scheme in Figure 1A, followed by formation of a soluble chelate between cationic, non-framework aluminum and EDTA. 

Alternatively, hydrolysis can be carried out with equally satisfactory results using 3 mL of saturated rac-tartaric acid soln and 2mL of pentane/mmol of imine obtained after solvent removal. The 2-alkyl ketones thus obtained were examined by GC and shown to be 98 2% pure. 

Lithium.—Lithium oxide was discovered by A. Arfvedson, in 1817,10 while analyzing the mineral petalite. His report was entitled Untersuehungen einiger hei der Eisen-Grube von Ulo vorkommenden Fossilien und von einem darin gefundenen neuen feuerfesten Alkali. He found the sodium to be contaminated by an alkali which, unlike potassium, was not removed as a precipitate by treatment with tartaric acid, and, unlike sodium, it formed a sparingly soluble carbonate. The... 

If the heat—374 —be carefully maintained for yet a longer time, anhydrous tartaric acid or tartaric anhydride remains in form of a white, porous mass insoluble in water. Adherent tartrelic acid is removed by washing with water till the wash liquor no-longer reddens litmus. By contact with co]d water for a few hours anhydrous tartaric acid resumes its basic water. 

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