Lead tartrate

Finely divided lead, when heated in air, forms first the lead(II) oxide, litharge , PbO, and then on further heating in an ample supply of air, dilead(II) lead(IV) oxide, red lead , Pb304. Lead, in a very finely divided state, when allowed to fall through air, ignites and a shower of sparks is produced. Sueh finely divided powder is said to be pyrophoric . It can be prepared by carefully heating lead tartrate. 

There is a very spectacular reaction with the charring of lead tartrate. When this residue is freshly prepared, it combusts spontaneously in air by throwing up showers of sparks. When it is rubbed on a sheet of paper, or put in the hand and thrown, the reactions of this residue are more violent. It is thought that this is due to the catalysis by lead oxide of the combustion of carbon formed, which is very porous. 

In 1884, Emerson-Reynolds reported deposition of PbS films by reaction between thiourea (thiocarbamide) and alkaline lead tartrate, where the metallic sulphide. .. became firmly attached as a specular layer to the sides of the vessel [6], A wide range of substrates, apart from that just mentioned (a glass beaker), was successfully used for this deposition porcelain, ebonite, iron, steel, and brass were specifically mentioned. Even more important, the deposits were very adherent, as quantified by their ability to withstand considerable friction with a wash-leather, and under this treatment take a fine polish. ... 

The second study of possible relevance reported that PbSe, precipitated from selenosulphate solution (not in the form of a film), was found to have an (electrical) bandgap, measured by temperature-dependent resistivity, of 0.4 eV [48], In the same study, samples prepared by reaction of solid lead tartrate with H2Se exhibited an electrical bandgap of 0.92 eV. These results suggest the occurrence of size quantization. 

Auxiliary complexing agents such as NH3, tartrate, citrate, or triethanolamine may be employed to prevent metal ion from precipitating in the absence of EDTA. For example, Pb2+ is titrated in NH, buffer at pH 10 in the presence of tartrate, which complexes Pb2+ and does not allow Pb(OH)2 to precipitate. The lead-tartrate complex must be less stable than the lead-EDTA complex, or the titration would not be feasible. 

Suspensions of oxidizable particles (e.g., flour, coal dust, magnesium powder, zinc dust, carbon powder, and flowers of sulfur) in the air can constitute a powerful explosive mixture. These materials should be used with adequate ventilation and should not be exposed to ignition sources. Some solid materials, when finely divided, are spontaneously combustible if allowed to dry while exposed to air. These materials include zirconium, titanium, Raney nickel, finely divided lead (such as prepared by p5trolysis of lead tartrate), and catalysts such as activated carhon containing active metals and hydrogen. 

The variable contents of lead chromate and lead sulfate in solid solution cause changes in the crystal structure. Lead chromate sulfates with a PbCr04 content of >30-35% have monoclinic symmetry (as does pure lead chromate(VI), q.v.)-, a lead chromate content of <10%, results in a pigment with orthorhombic symmetry (Watson and Clay, 1955), although stabilisation by additives such as lead tartrate, metal oxide or hydroxide is required to prevent conversion back to the mono-clinic form (Wormald, 1975) lead chromate sulfates of intermediate composition (that is, those containing 10-30% PbCr04) result in co-precipitation of both structures (Watson and Clay). Thus, in terms of the ATSM standard, all types of lead chromate sulfate are monoclinic. However, the review by Kuhn and Curran reports that some modern commercial examples of the primrose type, particularly the pale varieties (which presumably contain more lead sulfate), may have a much lower lead chromate(Vl) content, and can be precipitated in the orthorhombic form if the lead chromate content falls below 10% and stabilisers are used. They also state that more recent products may be stabiUsed in the orthorhombic form with a PbCr04 content of up to 85%. 

A simple test for aliphatic dithiocyanates consists in the development of a red color on the addition of ferric chloride to a solution formed by heating the thiocyanate with aqueous sodium hydroxide followed by acidification. A few instances have been reported in which a monothiocyano compound produces a red color with ferric chloride alone. A more general test involves heating a thiocyanate with alkaline lead tartrate, which results in the formation of a yellow precipitate. The reaction with sodium malonic ester to produce a disulfide has been suggested as a qualitative test. A method for the quantitative determination involves heating the compound under reflux with an ethanolic solution of sodium... 

An interesting application of lead tetra acetate is to the jireparation of the otherwise dilliculty-accessiblo a-butyl glyoxylate (II) by oxidation of di-a-butyl i-tartrate (I) ... 

Place a mixture of 125 ml. of A.R. benzene and 32 -5 g. of di-re-butyl d-tartrate (1) in a 500 ml. three-uccked flask, equipped with a Hershberg stirrer (Section 11,7) and a thermometer. Stir the mixture rapidly and add 58 g. of lead tetra-acetate (Section 11,50,15) in small portions over a period of 20 minutes whilst maintaining the temperature below 30° by occasional cooling with cold water. Continue the stirring for a further 60 minutes. Separate the salts by suction filtration and wash with two... 

Direct Titrations. The most convenient and simplest manner is the measured addition of a standard chelon solution to the sample solution (brought to the proper conditions of pH, buffer, etc.) until the metal ion is stoichiometrically chelated. Auxiliary complexing agents such as citrate, tartrate, or triethanolamine are added, if necessary, to prevent the precipitation of metal hydroxides or basic salts at the optimum pH for titration. Eor example, tartrate is added in the direct titration of lead. If a pH range of 9 to 10 is suitable, a buffer of ammonia and ammonium chloride is often added in relatively concentrated form, both to adjust the pH and to supply ammonia as an auxiliary complexing agent for those metal ions which form ammine complexes. A few metals, notably iron(III), bismuth, and thorium, are titrated in acid solution. 

Polymers containing 8-hydroxyquinoline appear to be selective adsorbents for tungsten in alkaline brines (95). In the presence of tartrate and citrate, quinaldic acid [93-10-7] allows the separation of zinc from gallium and indium (96). Either of these compounds can selectively separate lead and zinc from oxide ores as complexes (97). It is also possible to separate by extraction micro quantities of rhenium(VII), using quinoline in basic solution (98). The... 

Condensation of piperazine with 2-methoxytropone gives the addition-elimination product 12 [2]. Alkylation of the remaining secondary amino group with bromoketone 13, itself the product from acylation of dimethyl catechol, gives aminoketone 14. Reduction of the carbonyl group with sodium borohydride leads to secondaiy alcohols 15 and 16. Resolution of these two enantiomers was achieved by recrystallization of their tartrate salts to give ciladopa (16) [3],... 

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. 

Pb2+ Tartrate buffer or chloride solution (solubility limits the amount of lead to less than 50 mg per 100 mL) 2 A 2-3 V... 

In a similar determination described by Lingane and Jones,11 an alloy containing copper, bismuth, lead, and tin is dissolved in hydrochloric acid as described above, and then 100 mL of sodium tartrate solution (0.1 M) is added, followed by sufficient sodium hydroxide solution (5M) to adjust the pH to 5.0. After the addition of hydrazinium chloride (4 g), the solution is warmed to 70 °C and then electrolysed. Copper is deposited at —0.3 volt, and then sequentially, bismuth at —0.4 volt, and lead at —0.6 volt all cathode potentials quoted are vs the S.C.E. After deposition of the lead, the solution is acidified with hydrochloric acid and the tin then deposited at a cathode potential of — 0.65 volt vs the S.C.E. 

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. 

The completion of the synthesis of 1 required installation of the (R)-nipecotic moiety. The original method used (R)-ethyl nipecotate L-tartrate 21, which was commercially available, but the availability of this intermediate on multi-kilogram scale required long lead times and cost was a major factor. In addition, it was also discovered that saponification of the ethyl ester in the final stages of the synthesis, as shown in Scheme 7.3, was accompanied by small amounts of epimerization at the carboxylic acid center of 1, resulting in diastereomeric contamination of the final product. 

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