Search Results

You are looking at 51 - 60 of 62 items for

  • Author or Editor: G. Liptay x
  • Refine by Access: All Content x
Clear All Modify Search

Kinetic analysis of thermogravimetric data

XXVIII Thermal decomposition of some metal and ammonium salts of hexabromoplatinic acid

Journal of Thermal Analysis and Calorimetry
Authors: G. Liptay, J. Zsakó, Cs. Várhelyi, and Cs. Novák
Restricted access

The DTA method has been used in studying the thermal dehydration and decomposition of NiSO4.nH2O, accordingly of NiSO4.nD2O, (atn=7, 6, 4, 1) in a temperature interval of 20 to 900°C, at a heating rate of 10 deg/min. The endoeffects observed show in all cases partial dehydration to monohydrate and evolution of the last molecule of hydrate water at a high temperature Tmax ∼-360°C for the hydrates and Tmax ∼ 360-335°C for the deuterates. At NiSO4.6H2O (6D2O) and NiSO4.4D2O there occurs stepwise dehydration before the monohydrate as well. Decomposition of the anhydrous NiSO4 takes place at higher temperature which depends on whether it had been obtained from the respective deuterate ordinary hydrate. The one obtained from the deuterate undergoes decomposition at relatively lower temperature.

Restricted access

Kinetic analysis of thermogravimetric data. X

Thermal decomposition of some tris-ethylenediamine-cobalt(III) and chromium(III) complexes

Journal of Thermal Analysis and Calorimetry
Authors: J. Zsakó, Cs. Várhelyi, G. Liptay, and K. Szilágyi

A study was made of the thermal decompositions of 22 derivatives of[M(en) 3]X 3 type complexes. Partial de-amination leading to the formation of[M(en) 2 X 2]X type complexes occurs in the case ofM=Cr(III) ifX=Cl, Br, I orNCS, but in the case ofM=Co(III) it is possible only ifX=Cl. In other cases redox reactions hinder the formation of stable intermediates. Kinetic parameters were derived for the dehydration of 19 compounds.

Restricted access

Kinetic analysis of thermogravimetric data

XXVII. Thermal decomposition of some metal and ammonium salts of hexachloroplatinic acid

Journal of Thermal Analysis and Calorimetry
Authors: J. Zsakó, G. Liptay, Cs. Várhelyi, Cs. Novák, and I. Ganescu

Nineteen salts of hexachloroplatinic acid with monovalent metals, aromatic and heterocyclic amines and phosphine were obtained and characterized by chemical analysis. The thermal decomposition of these complexes was studied by means of derivatograph and differential scanning calorimetry. The nature of the pyrolysis processes is discussed. From the TG curves, kinetic parameters were derived for different stages of the thermal decompositions.

Restricted access

Abstract  

Montmorillonite-supported iron(III) nitrate and copper(II) nitrate reagents, and other supported metal nitrates prepared in the same way, were investigated by thermal and X-ray powder diffraction methods. The metal nitrates are present on the support in the form of crystalline hydrate and not as acetone solvate as supposed earlier. Thermal decomposition of metal nitrates that are active in model reactions proceeds in a different way from that of the practically inactive nitrates. In the former case, water release and nitrate decomposition itself are simultaneous process. These and other results contributed to determination of suitable reaction conditions for the montmorillonite-supported reagents.

Restricted access

Abstract  

A number of 30 [Co(en)3 ]Y3 , [Co(en)2 X2 ]Y and [Co(en)2 X(amine)]Y2 type complexes (X =Cl, Br; Y =Cl, Br, I, NCO, NCS, NO3 , ClO4 , etc.; amine =aromatic and alkylamines) were obtained from trans-[Co(en)2 Cl2 ]Cl by double decomposition and by substitution reactions, respectively. The structure of the complexes was proved by means of far and middle FTIR spectra. The thermal decomposition was studied by TG, DTA and DSC measurements. Mass spectra were also recorded. In the case of [Co(en)3 ]Y3 complexes the nitrate, perchlorate and dimesoperiodates decompose suddenly, frequently explosion like. The halides and thiocyanates seem to substitute an ethylenediamine ligand, yielding a rather unstable intermediate. The pyrolysis of [Co(en)2 X2 ]Y type derivatives yields no relatively stable intermediates, but the decomposition temperatures may be correlated with the nature of Y and with the cis or trans configuration of the compound. With the [Co(en)2 X(amine)]Y2 type complexes one observes the formation of [Co(en)2 XY]Y as intermediate product. From the TG curves kinetic parameters were derived for some dehydration and deamination processes, by using the nomogram method. The validity of a non-linear kinetic compensation law was observed.

Restricted access

On the oximine complexes of transitionmetals

Part CXIX. Thermal and spectral studies on Ni(Diox.H)2 type chelate compounds

Journal of Thermal Analysis and Calorimetry
Authors: Cs. Várhelyi Jr., G. Pokol, Á. Gömöry, A. Gănescu, P. Sohár, G. Liptay, and Cs. Várhelyi

Abstract  

Fourteen chelates of the type [Ni(II)(Diox.H)2], ((Diox.H)2: various α-dioximes) have been studied by means of FTIR, NMR, MS data and various thermoanalytical methods (TG, DTA, DTG, DSC). In some cases kinetic parameters of the thermal decomposition of the complexes were also calculated using Zsak’s ‘nomogram method’. The mechanism of the decomposition processes was characterised on the basis of mass spectra.

Restricted access

Abstract  

Compounds obtained by a solid–gas phase reactions between copper(II) chloride and bromide and 2,4-, 2,6- 3,4- and 3,5-lutidines were studied using thermogravimetry, far-infrared, electronic spectroscopy and X-ray diffraction. The results were compared with the corresponding data for the similar compounds with methylpyridines and 2,4,6-collidine. A special attention was paid to the host-guest phenomenon, a new structural feature of transition-metal halide complexes.

Restricted access
Restricted access