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1.
The thermal decomposition of piperidine hydrothiocyanate, piperazine hydrothiocyanate, and the dihydrothiocyanates of ethylenediamine and 1,3-diaminopropane has been studied using TG. Piperidine hydrothiocyanate decomposes in a single step while the dihydrothiocyanates follow more complicated decomposition patterns yielding H2S and half of the organic moiety first. The second step involves the loss of H2S and the remainder of the organic moiety. In each case, complex polymeric materials result. Piperazine hydrothiocyanate also decomposes in two steps, the first involving the loss of half of the piperazine and the second involving the loss of piperazine and H2S. Kinetic parameters have been determined for all these reactions. 相似文献
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3.
Summary The deaquation-anation of solid aquapentamminecobalt(III) chloride was studied isothermally and non-isothermally. Kinetic data were obtained from t.g.a. and were analysed using 17 rate laws known for solid state reactions. This reaction, long interpreted as SN2, was found to obey an A1.5 rate law from both types of experiments. From the isothermal experiments, an E
a of 97.0 kJ mol-1 was found. 相似文献
4.
Precise conductance measurements are reported on dilute aqueous solutions of the sodium and potassium salts of orthophosphoric
acid at 25 ∘C. Conductance measurements on solutions of electrolytes such as these phosphate salts that exist in solution as complicated
mixtures of ions have previously proved difficult to interpret. To overcome this, a mathematical method has been developed
to calculate the concentrations of all the species in the aqueous system M3PO4/M2HPO4/M2HPO4/H3PO4 (M = Na or K) over a continuous range of stoichiometries. The Lee–Wheaton conductance equation has been used to interpret
the conductance of these multicomponent solutions in terms of the limiting ionic conductances and concentrations of all the
ions in the solution. The limiting molar conductances of the ions H2PO4
− and HPO4
2− and the ion-pair formation constants of these ions with sodium and potassium ions were determine
This work has enabled the accurate determination of solution parameters for the important hydrogenphosphate ions in water
and provides an excellent example of the use of an advanced conductance theory in the analysis of the conductance of multicomponent
electrolyte systems. 相似文献
5.
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. 相似文献
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Thermal studies have been carried out on trans-[Co(NH3)4Cl2]X · YH2O complexes (whereX=IO3, BrO3, NO3, or NO2 andY=0, 1, or 2) in an effort to find cases of trans to cis isomerization as occurs for the iodate. No evidence of isomerization was found for any of the other compounds. The complexes decompose in a series of steps and these reactions have been identified and kinetic parameters determined. 相似文献
9.
TG and DTG studies have been carried out on CoS2O6 · 6H2O, NiS2O6 · 6 H2O, CuS2O6 · 3.5 H2O, ZnS2O6 · 6 H2O and CdS2O6 · 4H2O. After partial dehydration, the dithionates of Co(II), Ni(II), Cu(II) and Zn(II) lose water and sulfur dioxide simultaneously to yield the stable metal sulfates in the final step of decomposition. The CdS2O6 · 4H2O dehydrates completely in the first two steps of decomposition with two water molecules being lost in each step. In the third step, it loses only SO2 to yield CdSO4. Kinetic parameters are presented for these reactions.
Zusammenfassung TG- und DTG-Untersuchungen von CoS2O6 · 4 H2O, NiS2O6 · 6 H2O, CuS2O6 · 3.5 H2O, ZnS2O6 · 6 H2O und CdS2O6 · 4 H2O wurden ausgeführt. Nach partieller Dehydratisierung geben die Dithionate von Co(II), Ni(II), Cu(II) und Zn(II) im letzten Schritt des Abbaus gleichzeitig Wasser und Schwefeldioxid unter Bildung der stabilen Metallsulfate ab. CdS2O6 · 4 H2O wird in den ersten beiden Zersetzungsschritten unter Abgabe von je 2 Wassermolekülen vollständing zersetzt. Im dritten Schritt wird nur SO2 unter Bildung von CdSO4 abgegeben. Kinetische Parameter dieser Reaktionen werden angegeben.
CoS2O6 · 6 H2O, NiS2O6 · 6 H2O, CuS2O6 · 3.5 H2O, ZnS2O6 · 6 H2O CdS2O6 · 4 H2O. , , , , . , . , . .相似文献
10.
Thiiranium (episulfonium) ions had been acknowledged as reaction intermediates for many years, but it was not until 1977 that Nicolaou demonstrated systematically that these reactive heterocyclic cations could be trapped by carboxylic acids to give lactones. In the years that followed this report, extensive research greatly extended the scope of this reaction, particularly with regard to the methods for generating thiiranium ions, the types of nucleophiles that are compatible with this reaction, and the selectivity involved in the cyclization reactions. For many years we have been using thiiranium ions for the synthesis of saturated heterocycles. Whereas Nicolaou's method relied on electrophilic sulfenylation of alkenes, we have generated thiiranium ions by displacement of a leaving group with neighboring-group participation by a sulfanyl group. Many of the examples we have reported are of cyclizations that are reversible and so where two (and in some cases more) products can result, the outcome of the reactions provides fundamental information about the relative stability of different heterocyclic ring systems. This Review will begin with a brief introduction to sulfanyl participation as a method for generating thiiranium (and thiolanium) ions, and will go on to explore the idea of using sulfanyl migrations in synthesis. Initially, emphasis will be placed on mechanisms of [1,2] sulfanyl migrations: we will look specifically at [1,2] sulfanyl migrations (usually PhS) with elimination, substitution, and cyclization. Emphasis will then shift to the factors that affect the outcome of cyclization reactions. In particular, we will cover cyclizations with hydroxy nucleophiles and examine situations in which there are more than one hydroxy nucleophile present. We will also examine cyclizations with other nucleophiles, namely amines and sulfides. After our discussion of [1,2] sulfanyl migrations, we will look very briefly at the scope of [1,4] sulfanyl participation, before finally drawing up some guidelines that (we hope) will help other organic chemists take advantage of the rearrangement reactions that the sulfanyl group has to offer. 相似文献