M.R. Udupa

Thermal behaviour of ethylenediammonium perchlorate

Perchlorates are powerful oxidizing agents [1] and are used as oxidants in explosives, pyrotechnics and solid state rocket propellants. Extensive studies have been made on the thermal stability of ammonium and related perchlorates due to their technological importance as oxidants [2,3]. This note reports the preparation, characterization and thermal behaviour of ethylenediammonium perchlorate. The study has been followed by XRD, IR, TG, DTA and MS techniques.

Thermal behaviour of morpholinium perchlorate

Abstract Morpholine is a base of moderate strength, comparable with that of ammonia, and capable of forming -onium-type salts. Extensive studies [1,2] have been made on the thermal stability of ammonium perchlorate because of its technological use as an oxidant in solid state rocket propellants. The preparation, characterization and thermal behaviour of morpholinium perchlorate are reported in this note. The study was followed by XRD, IR, TG, DTA and mass spectral techniques.

Thermal decomposition of potassium perchlorate in presence of chromium(III) oxide and nickel(II) chromite(III)

Abstract A study of the thermal decomposition of intimate mixtures of different molar ratios of potassium perchlorate and chromium(III) oxide, and potassium perchlorate and nickel(II) chromite(III) was conducted employing thermogravimetry, differential thermal analysis, chemical analysis, infrared spectroscopy and X-ray diffraction analysis. Upon heating to 400°C Cr(III), in 2:1 molar ratios, is oxidized to potassium dichromate. Only a stoichiometric amount of Cr(III) was oxidized from molar ratios less than 2:1, leaving behind excess Cr2O3 and NiCr2O4 whereas from molar ratios greater than 2:1, Cr(III) was completely oxidized and the excess KClO4 started decomposing around 410°C which is much below the decomposition temperature of pure KClO4.

TGA, DTA and DSC studies of phosphiniminocyclotrithiazenes, R3P=NS3N3 [R=(i) C6H5-, (ii) C5H10N-, (iii) OC4H8N-, (iv) H3CNC4H8N-]

Abstract Thermal decomposition behaviour of phosphiniminocyclotrithiazenes [R=(i) phenyl-, (ii) piperidino-, (iii) morpholino- and (iv) N -methylpiperazino-] have been studied for the first time by employing thermogravimetric (TG), differential thermal (DT) and differential scanning calorimetric (DSC) methods. These heterocycles which do not show any melting behaviour begin to decompose above 130°C by following different pathways. The study indicates the possibility of obtaining new products by controlled solid-state pyrolysis method. Thermo-chemical parameters for the decomposition process have also been evaluated.

Thermal decomposition of vanadium oxysalts

Abstract The study of the thermal decomposition of V 2 (SO 4 ) 3 , VOSO 4 · 5 H 2 O, VO(CH 3 -(COO) 2 and VOC 2 O 4 · 2 H 2 O has been made in argon and hydrogen atmospheres and compared with that in air by following thermogravimetry and differential thermal analysis. The decomposition products are characterized by chemical analysis, IR, and X-ray powder diffraction methods. The results suggest that all the salts decompose to V 2 O 5 in air and to V 2 O 3 in hydrogen. In argon atmosphere, the sulphates decompose to V 2 O 5 whereas the carboxylates decompose to V 2 O 3 .

The thermal decomposition of potassium bromate in the presence of chromium(III) oxide

Abstract Thermal decomposition studies of intimate mixtures of different molar ratios of potassium nitrate and chromium(III) oxide were made by employing thermogravimetry differential thermal analysis, chemical analysis, infrared spectral measurements and X-ray powder diffraction patterns. Potassium nitrate in the presence of chromium(III) oxide starts decomposing around 350°C which is much below the decomposition temperature of pure potassium nitrate. Chromium(III) is completely oxidized into its hexavalent state when the mole ratio of KNO3 to Cr2O3 is greater than three.

Thermal decomposition of thallium(I) perchlorate in presence of chromium(III) oxide

Abstract Thermal decomposition of an intimate mixture of thallium(I) perchlorate and chromium(III) oxide revealed that chromium(III) oxide lowers the decomposition temperature of thallium(I) perchlorate and is oxidized into hexavalent state to give thallium(I) dichromate. The thermal decomposition was followed by constant temperature heating, thermogravimetry and differential thermal analysis. The reaction products were characterized by chemical analysis, X-ray diffraction and infrared spectral measurements.

Solid state reactions in the system oxalate-bromate-chromium(III) oxide

Abstract The TG and DTA techniques in static air atmosphere have been employed to study the thermal behaviour of intimate mixtures comprising different mole ratios of potassium oxalate, potassium bromate and chromium(III) oxide. The products are characterised by chemical analysis, infrared spectroscopy and X-ray diffraction studies. The studies indicate that the onset of the reaction occurs after the dehydration of potassium oxalate around 200°C. Also it suggests that the chromium(III) oxide initiates the decomposition of potassium bromate at a lower temperature resulting in the liberation of oxygen which is utilised in the oxidative decomposition of potassium oxalate. With the stoichiometric amounts (3:3:1 molar ratio) of potassium bromate, potassium oxalate and chromium(III) oxide the reaction gives rise to a mixture of potassium chromate, potassium carbonate and potassium bromide in the molar ratio of 2:2:1.

Thermochemical investigation of solid state reactions in molybdates/tungstates system

Abstract Investigation on the influence of MoO 3 and WO 3 on the thermal decomposition of the halogen oxysalts, KClO 4 , KClO 3 , KBrO 3 and KIO 3 has been followed by TG, DTA, IR spectroscopy and X-ray diffraction studies. The results suggest the formation of mono-, di-, tri- and tetra- molybdates/tungstates in solid state by the reaction of appropriate mole ratios of the reactants.

Thermal behaviour of chromium (III) perchlorate hexahydrate

Abstract Thermal behaviour of intimate mixtures of chromium(III) oxide and lithium1, potassium2, rubidium3, cesium3 and thallium(I)4 perchlorates revealed that chromium(III) oxide not only catalyses the decomposition by lowering the decomposition temperatures of the pure metal perchlorates but also chemically interacts resulting in the formation of metal dichromate. The oxidation of chromium(III) into the hexavalent state is attributed to the abstraction of oxygen from the perchlorate moiety during the decomposition. In this context, it was thought interesting to study the thermal behaviour of chromium(III) perchlorate and to identify the decomposition products in order to find out whether chromium(III) is oxidized into chromium(VI) by the perchlorate group. Except for a report5 on the preparation of chromium(III) perchlorate with different molecules of water of hydration no work seems to have been carried out on the thermal decomposition of this compound. In the present study, the decomposition characteristics are followed by TG and DTA techniques and the decomposition products have been examined by chemical analysis, X-ray powder diffraction patterns and infrared spectral measurements.