Cadmium tartrate

Some cadmium compounds, including simple salts, were revealed to be excellent catalysts for the enantiosymmetric polymerisation of propylene sulphide [156,157], For instance, the proportion of isotactic diads in the polypropylene sulphide) sample obtained in polymerisation with the cadmium (7 )-tartrate catalyst was more than 95%, higher than the 69% which was characteristic of a polymer sample prepared using the zinc (i )-tartrate catalyst [158]. The superior stereoselectivity of the cadmium (i )-tartrate catalyst is also borne out by the more effective separation into fractions having opposite optical rotations of the polypropylene sulphide) yielded by cadmium tartrate, compared with that yielded by zinc (i )-tartrate. Note the quite different behaviour of these two catalysts in terms of their stereoelectivity in the polymerisation of propylene sulphide only very slight optical activity was found for the polypropylene sulphide) sample prepared using cadmium tartrate, whereas that associated with the polymer sample obtained with zinc tartrate was found to have a much higher value [158]. 

In benzene solution at 25°C, ZnEt2/H20, cadmium tartrate initiator Intrinsic viscosity 2.0-4.0 (14)... 

Fig. 15. Optical activity of poly (methyl thiirane) prepaied using sodium ( ) and cadmium tartrate...

The polymerization of thiirans generally " and of stereoregular and optically active polymers of thiirans has been reviewed. The development of optical activity in the polymerization of racemic 2-methylthiiran by n-butyl-lithium-lithium(-)-menthoxide depends on the selective polymerization of (S)-2-methylthiiran by the catalyst system, the selective desulphurization of (R)-2-methylthiiran, and the selective decomposition of (S)-polymer chains. Crystalline polymers of racemic isopropylthiiran were obtained with initiators, e.g. diethylzinc or cadmium tartrate. A number of polymers and copolymers involving thiirans have been reported. ... 

D. Benzoin-a-oxime (cupron) (VII). This compound yields a green predpitate, CuC14Hu02N, with copper in dilute ammoniacal solution, which may be dried to constant weight at 100 °C. Ions which are predpitated by aqueous ammonia are kept in solution by the addition of tartrate the reagent is then spedfic for copper. Copper may thus be separated from cadmium, lead, nickel, cobalt, zinc, aluminium, and small amounts of iron. 

H. 8-Hydroxyquinaldine (XI). The reactions of 8-hydroxyquinaldine are, in general, similar to 8-hydroxyquinoline described under (C) above, but unlike the latter it does not produce an insoluble complex with aluminium. In acetic acid-acetate solution precipitates are formed with bismuth, cadmium, copper, iron(II) and iron(III), chromium, manganese, nickel, silver, zinc, titanium (Ti02 + ), molybdate, tungstate, and vanadate. The same ions are precipitated in ammoniacal solution with the exception of molybdate, tungstate, and vanadate, but with the addition of lead, calcium, strontium, and magnesium aluminium is not precipitated, but tartrate must be added to prevent the separation of aluminium hydroxide. 

Sulphuric acid is not recommended, because sulphate ions have a certain tendency to form complexes with iron(III) ions. Silver, copper, nickel, cobalt, titanium, uranium, molybdenum, mercury (>lgL-1), zinc, cadmium, and bismuth interfere. Mercury(I) and tin(II) salts, if present, should be converted into the mercury(II) and tin(IV) salts, otherwise the colour is destroyed. Phosphates, arsenates, fluorides, oxalates, and tartrates interfere, since they form fairly stable complexes with iron(III) ions the influence of phosphates and arsenates is reduced by the presence of a comparatively high concentration of acid. 

Fluoride, in the absence of interfering anions (including phosphate, molybdate, citrate, and tartrate) and interfering cations (including cadmium, tin, strontium, iron, and particularly zirconium, cobalt, lead, nickel, zinc, copper, and aluminium), may be determined with thorium chloranilate in aqueous 2-methoxyethanol at pH 4.5 the absorbance is measured at 540 nm or, for small concentrations 0-2.0 mg L 1 at 330 nm. 

Discussion. Cadmium may be precipitated quantitatively in alkaline solution in the presence of tartrate by 2-(2-hydroxyphenyl)benzoxazole. The complex dissolves readily in glacial acetic acid, giving a solution with an orange tint and a bright blue fluorescence in ultraviolet light. The acetic (ethanoic) acid solution is used as a basis for the fluorimetric determination of cadmium.28... 

Most linear celluloses may be dissolved in solvents capable of breaking the strong hydrogen bonds. These solutions include aqueous solutions of inorganic acids, calcium thiocyanate, zinc chloride, lithium chloride, ammonium hydroxide, iron sodium tartrate, and cadmium or copper ammonium hydroxide (Schweitzer s reagent). The product precipitated by the addition of a nonsolvent to these solutions is a highly amorphous, regenerated cellulose. 

Chlorpromazine formed an insoluble 1 1 complex with lead picrate, and 5 3 complexes with the picrates of cadmium, copper, and zinc [70]. The sample (0.1 g) was dissolved in 15 mL of 95% ethanol, and the solution adjusted to pH 9 with 0.1 N NaOH. After adding 25 mL of a 0.02 M picrate reagent (30 mL of Pb), the solution was set aside for 2 hours. The precipitate was collected on a sintered glass fuimel, and the unconsumed metal in the filtrate was titrated directly with 0.02M EDTA at pH 10.4 (after adding 0.5 g of potassium sodium tartrate for Pb). Eriochrome black T was used as the indicator. 

The interference of copper, nickel, cobalt, iron, chromium, and magnesium is prevented by adding sodium potassium tartrate to the test solution only silver (removed as silver iodide by the addition of a little KI solution) and mercury then interfere. Mercury is best removed by adding a little sodium potassium tartrate, a few crystals of hydroxylamine hydrochloride, followed by sodium hydroxide solution until alkaline the mercury is precipitated as metal. Tin(II) chloride is not suitable for this reduction since most of the cadmium is adsorbed on the mercury precipitate. 

Cadmium acetate solution white, gelatinous precipitate of cadmium citrate Cd3(C6H507)2, practically insoluble in boiling water, but readily soluble in warm acetic acid (tartrate gives no precipitate). 

Cyanide solutions are used in the electroplating of gold, silver, zinc, cadmium, and other metals. In these solutions the concentrations of uncomplexed metal ions are very small, and this favors the production of a uniform fine-gTained deposit. Other complex-forming anions (tartrate, citrate, chloride, hydroxide) are also used in plating solutions. 

Coulometric determinations of metals with a mercury cathode have been described by Lingane. From a tartrate solution, copper, bismuth, lead, and cadmium were successively removed by applying the appropriate cathode potential, which was selected to correspond to a region of diffusion-controlled current determined from current-voltage curves with a dropping mercury electrode. With a silver anode, iodide, bromide, and chloride can be deposited quantitatively as the silver salt. By controlling the anode potential, Lingane and Small determined iodide in the presence of bromide or chloride. The separation of bromide and chloride, however, was not successful because solid solutions were formed (Section 9-4). 

Cadmium may be extracted into CHCI3 or CCI4 as the dithiocarbamate [11,12]. In the presence of tartrate and cyanide at pH 11, only Bi, Pb, and Tl(ni) are co-extracted with cadmium. Dithizone allows a highly selective separation of cadmium. Separation of Cd (and Zn) from Co and Ni has been described [13]. 

The cadmium ion reacts with dithizone (Section 4.5) in neutral to strongly alkaline media to give a pink cadmium dithizonate, which is soluble in CCI4 and in CHCI3. The stability of Cd(HDz)2 in strongly alkaline media (5-20% NaOH) allows cadmium to be extracted from Pb, Bi, Sn(II), and Zn, the dithizonates of which cannot exist under such conditions. Dimethylglyoxime is added to mask nickel and cobalt. Tartrate prevents the precipitation of metals as hydroxides. The noble metals (Au, Pt, Pd, Ag, Hg) and Cu must be removed before cadmium is extracted. They are most simply pre-extracted with dithizone from acid medium. 

Standard cadmium solution 1 mg/ml. Dissolve 1.6310 g of cadmium chloride, dried at 110°C, in water containing 2 ml of cone. HCl, and dilute the solution with water to 1 litre. Potassium sodium tartrate, 20% solution (preparation as in Section 27.2.1). Hydroxylamine hydrochloride, 10% solution (preparation as in Section 27.2.1). 

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