Thallium -malonate

Thallium malonate can be prepared by treating TI3CO3 with an equimolar quantity of malonic acid dissolved in water (solubility 73.5% at 20°C) and evaporating. Thallium malonate deliquesces in air. 

The true density of fibres was determined by flotation in thallium malonate/thallium formate solutions (Clerici solutiais) by grinding small amounts of fibre, suspension in a soluticn of known density, and centrifuging. When no separaticm occurred cn centrifuging the fibre density was taken to be that of the solution. The precisicn of the method is +-0.05g/inl. 

Uses. Tballium compounds have limited use in industrial appHcations. The use of thaHous sulfate in rodenticides and insecticides has been replaced by other compounds less harmful to animals (see Insect control technology Pesticides). Tb allium sulfide has been used in photoelectric cells (see Photovoltaic cells). A thallium bromide—thallium iodide mixture is used to transmit infrared radiation for signal systems. ThaHous oxide is used in the manufacture of glass (qv) that has a high coefficient of refraction. Tb allium formate—malonate aqueous solutions (Cletici s solution) have been used in mineral separations. Many thallium compounds have been used as reagents in organic synthesis in researchlaboratoti.es. 

N-Alkylations, especially of oxo-di- and tetra-hydro derivatives, e.g. (28)->(29), have been carried out readily using a variety of reagents such as (usual) alkyl halide/alkali, alkyl sulfate/alkali, alkyl halide, tosylate or sulfate/NaH, trialkyloxonium fluoroborate and other Meerwein-type reagents, alcohols/DCCI, diazoalkanes, alkyl carbonates, oxalates or malon-ates, oxosulfonium ylides, DMF dimethyl acetal, and triethyl orthoformate/AcjO. Also used have been alkyl halide/lithium diisopropylamide and in one case benzyl chloride on the thallium derivative. In neutral conditions 8-alkylation is observed and preparation of some 8-nucleosides has also been reported (78JOC828, 77JOC997, 72JOC3975, 72JOC3980). 

The reaction of 4a-chlorotetrahydrocarbazole (549) and thallium(I) malonate in boiling benzene for 18 hr gave spiro-malonate (550) in 47% yield (78JOC3702). 

However, the usual skepticism concerning the solution X-ray diffraction method applied to weak interactions should be exercised, in particular in the malonate case where the temperature factors for all interactions involving thallium(I) were found to be very large. With increasing water content, and thus coming closer to what we normally mean by aqueous solution, the polynuclear units decompose. From the measured physicochemical properties, such as density, refractive index, specific... 

Fig. 8. Model of the structure of thallium(I) carboxylate species in highly concentrated aqueous solutions. Temperature = 25°C. (a) Formate species. [Tl]t t = 10.8 M, [H2O]/ [TKD] = 2.6, [formate ]/[Tl(I)] = 1.0. Thalliumd) ions are fourfold coordinated by three formate oxygens and one weakly bound water molecule (not shown), (b) Malonate species. [TlJtot = 9-0 M, [H20]/[T1(D] = 3, [malonate "]/[Tl D] = 0.5. Fourfold oxygen coordination of thalliumd) ion is shown only for one T1(I) atom. Some interatomic distances are given (in angstroms). From Yamaguchi et al. 177).

The rates of alkaline hydrolysis of the half-esters, potassium ethyl oxalate, malonate, adipate, and sebacate were studied in the presence of potassium, sodium, lithium. thallium(I), calcium(II), barium(II), and hexamminecobalt(III) ions (106). On the basis of the results obtained, chelate formation between the metal ions and the transition state of the substrate was postulated. In these chelate structures (structures XXXVIII), formally similar to those postulated in the hydrolysis of a-amino esters (26), the metal ion facilitates the attack by the hydroxide ion by positioning it in a suitable manner. The rate of hydrolysis of the oxalate half-ester is greater than that of the malonate, which in turn is greater than that of the adipate. This is in the expected order of the stability of the metal chelates. The order for the rate of hydrolysis of the ethyl oxalate and ethyl malonate is Ca2+ Ba2+ > [Co(NH3)6]3+ > T1+. The hexamminecobalt(III) ion seems to be less effective than expected, since it is too large to satisfy the steric requirements of the chelate structures. The alkali metals were found to have marked negative specific salt effects on the rates of reaction of the adipate and sebacate, but only a small negative salt effect on the hydrolysis of potassium ethyl malonate. 

Aoyama H (1989) Distribution and excretion of thallium after oral and intraperitoneal administration of thallous malonate and thallous sulfate in hamsters. Bull Environ Contam Toxicol 42 456-463. 

Thallium formate and malonate solution (1 1) (saturated) (Cleric solution) 4.07 (12 C) 4.65 (50 C) 5 (95 C) charcoal by heating the diluted, solution. Somewhat difficult to prepare marked changes in density with temperature and evaporation. 

Thallium(ll) Formate, Thallium(l) Malonate, Clerici s Solution... 

Clericl s solution is prepared by dissolving equal weights of thallium formate and malonate in the minimum amount of water. 

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