Thermal properties of sodium metasilicate hydrates

The heats of fusion and heat capacities at 298.2 K of Na₂SiO₃·5H₂O, Na₂SiO₃·6H₂O and Na₂SiO₃·9H₂O have been measured by DSC. The enthalpies and entropies of fusion increase with the water content of the hydrate and the entropy of fusion per mole of water is almost constant. The application of DSC/DTA to the analysis of metasilicate hydrate mixtures is discussed.     

The deaquation reactions of some metal salt hydrates at elevated pressures

The deaquation reactions of BaCl₂·2H₂O, BaBr₂·2H₂O and CoCl₂·6H₂0 were studied by the thermal analysis techniques of thermogravimetry, differential thermal analysis (DTA), and electrical conductivity in the pressure range from one to 170 atm. In general, the effect of pressure on the TG curves increased the T_i and T_f values and also the reaction interval, (T_t—T_i). The DTA curves exhibited splittings into multiple peaks as a result of the increased pressure. These splittings were interpreted as due to the evolution of a liquid water phase followed b     

Thermal decomposition of alkali metal perchlorates

The effect of past mechanical history on the subsequent thermal decomposition kinetics of sodium, potassium, rubidium and caesium perchlorates, has been investigated. At low temperatures the decomposition of all these salts is significantly sensitized by pre-compression. At high temperatures, however, prior compression results in a lowered decomposition rate in the case of potassium, rubidium and caesium perchlorates and in an increase in the thermal reactivity of sodium perchlorate. The high temperature behaviour is shown to be an indirect consequence of the low temperature behaviour. The difference in behaviour between sodium perchlorate and the other alkali metal perchlorates is explained on the basis of the stability of the respective chlorates, formed during the low temperature decomposition. This is substantiated by experiments which show that the addition of sodium chlorate to sodium perchlorate brings about a sensitization while potassium perchlorate admixed with potassium chlorate results in a desensitization at high temperatures.     

Thermal studies on 2,6-xylyliminodiacetato compounds of some transition metal ions

Some new 2,6-xylyliminodiacetato compounds of Mn(II), Fe(III), Ni(III), Zn(II) and Cd(II) have been prepared in aqueous media. The thermal behaviour of these compounds has been studied by TG, DTG, and DSC techniques. Heats of dehydration have been calculated from the DSC curves.     

Thermal studies on metal dithiocarbamato complexes. A review

In the present review, the work done on thermal studies of metal dithiocarbamato complexes during the period 1969–1982 are given. The thermal studies include thermogravimetry, differential thermogravimetry, differential thermal analysis, differential scanning calorimetry and mass spectrometry. Fifty-two references are included.     

Studies on double selenates. I. Thermal decomposition of lanthanum and alkali metal double selenates

Thermogravimetry, differential thermal analysis and other methods of analysis have been used to study the decomposition of hydrated lanthanum and alkali metal double selenates up to 1300°C. The results showed slight variations in the initial temperature of the various intermediate decomposition stages of the double selenates, as compared with the initial temperature of the corresponding decomposition of the simple selenates. The results also permitted the suggestion of mechanisms of thermal decomposition of these compounds.     

Thermal and chromatographic behaviour of metal complexes. Part II. Complexes of platinum(II) with dipeptide ester

Experimental measurements of the rate of reduction of particles of Carol Lake and Kiruna ores have been made using pure hydrogen and pure carbon monoxide and mixtures of these two gases. The temperature range covered was 773–1143 K and throughout this range the reduction rate with hydrogen was greater than that with carbon monoxide. A retracting core model was found to best fit the experimental data even when granules of 9 × 10^?4 m diameter were used. Reduction with gas mixtures of hydrogen and carbon monoxide give rates intermediate between those of the pure gases.     

Thermal and chromatographic behaviour of metal complexes. Part III. Complexes of palladium(II) with iminodiacetic acid

A study of the thermal properties of the complexes formed between Pd(II) and iminodiacetic acid (IDA) and the chromatographic analysis of their thermal decomposition products have been carried out. The dehydration of the isolated compounds is detected above 100°C. The decarboxylation process of the COO^? groups takes place yielding CO₂ and CO simultaneously or consecutively if they are not coordinated, respectively. The formation of gases (methane, ethane, etc.) is also observed.     

Studies on pollutants: A new reagent for the detection of fluoride

A new solid analytical reagent is reported for the detection and semiquantitative determination of traces of fluoride. A blue (λ_max 590 nm) trypan blue dye is liberated from an insoluble zirconium-trypan blue complex by the action of fluoride in dilute acetic acid medium. The detection limit is 0.8 ppm and the range of semiquantitative determination is 0.8 to 8 ppm. The method is simple and can be conveniently used for field detection of fluoride in polluted waters.     

Thermal decomposition of ammonium metavanadate

Ammonium metavanadate is subjected to thermal treatment in the range 180–550°C and structural and surface area changes are studied by X-ray diffraction and N₂ adsorption. DTA and TGA show the existence of a large endotherm (260°C) possibly composed of several stages, and a much smaller one (340°C) which is responsible for evolution of the molecule of water associated with the V₂O₅ initially formed. Three exotherms also appear and explanations for their presence are given. The phases formed, as well as the specific surface areas, are determined for the products obtained in a vacuum and in the presence of water vapour, and changes in surface areas are related to the phase transformations and dehydration of the products formed during thermal treatment.     

Thermal studies on yttrium,neodymium and holmium oxalates

The thermal decomposition patterns of Y₂(C₂O₄)₃ · 9 H₂O, Nd₂(C₂O₄)₃ · 10 H₂O and Ho₂(C₂O₄)₃ · 5.5 H₂O have been studied using TG and DTG. The hydrated neodymium oxalate loses all the water of hydration in one step to give the anhydrous oxalate while Y₂(C₂O₄)₃ · 9 H₂O and Ho₂(C₂O₄)₃ · 5.5 H₂O involve four or more dehydration steps to yield the anhydrous oxalates. Further heating of the anhydrous oxalates results in the loss of CO₂ and CO to give the stable metal oxides.     

Thermal expansion coefficient of sheet molding compound

The thermal expansion coefficient (TEC) of sheet molding compound (SMC) was determined. The experimental determination was accomplished by measuring directly the changes in length of specimens induced by temperature changes. The theoretical derivation was completed by using existing formulae for unidirectional composites and then applying the averaging procedure to obtain the TEC for randomly oriented chopped-fiber composites (SMC).Based on the results of this paper, we observed that SMC tested exhibited strong non-homogeneity and anisotropy. The in-plane TEC was close to that of aluminum, but in the direction normal to the panel was about three times that of aluminum.     

Exchange of metal carbonyl moieties on germanes

For R₃Ge = GeH₃, CH₃GeH₂ or (CH₃)₂GeH, R₃GeCo(CO)₄ reacts in an ether solvent with Mn(CO)₅^? to give R₃GeMn(CO)₅ while Mn(CO)₅^? displaces Fe(CO)₄^2? or (GeH₃)Fe(CO)₄^? and Fe(CO)₄^2? displaces Co(CO)₄^?.     

Thermal analysis of cobalt,nickel and copper complexes of 2-aminothiazole

The thermal decomposition of 2-aminothiazole (2-amt) complexes of general formula M(2-amt)₂X₂ [M = Co(II) and Cu(II)] and Ni(2-amt)₄X₂ [X = Cl and Br] have been studied in air and argon by TG and DTG as well as by DTA in nitrogen; end products from the decompositions in air have been characterised by X-ray powder diffraction. Decomposition stoichiometries have been proposed and factors governing the thermal decomposition have been discussed.     

Antiferromagnetic complexes involving metalmetal bonds : I. Synthesis and molecular structure of an antiferromagnetic dimer with a CrCr bond

The binuclear complex (C₅H₅)₂Cr₂(S)(SCMe₃)₂ was prepared by refluxing a solution of chromocene and t-butylmercaptane in heptane. The structure of the product was determined by single crystal X-ray diffraction. The chronium atoms are linked by a sulphide bridge (SCr 2.24 Å;, <CrSCr 74.1° and two SCMe₃ bridges (CrS 2.38 Å;, <CrSCr 68.3–69.3°). The two cyclopentadienyl ligands (CC 1.41 Å;, CrC 2.23 Å;) are in apical positions, their ring planes being parallel to each other. The complex is an antiferromagnet (?2J cm^?1) despite the small CrSCr angles and short chromiumchromium distance (2.689 Å;) indicative of strong CrCr bonding.     

Thermal decomposition of diisopropyl peroxydicarbonate. CIDNP and product studies

The thermal decomposition of diisopropyl peroxydicarbonate (IPP) in two solvents (chlorobenzene and tetrachloroethylene) was studied by [¹H]NMR. In both solvents the major decomposition products, acetone and isopropanol, showed interesting CIDNP effects during the first few minutes of the decomposition at 60 and 75 respectively. For decomposition in the presence of excess di-t-butyl-p-cresol, no acetone was formed while the other CIDNP effects were completely suppressed. From these results and further analysis of the by-products, it is concluded that the observed CIDNP effects are closely connected with induced decomposition of IPP, starting by abstraction of the secondary H-atom of the isopropyl group.