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Some transition metal nitrate complexes with hexamethylenetetramine

Part LV. Preparation, X-ray crystallography and thermal decomposition

Journal of Thermal Analysis and Calorimetry
Authors: G. Singh, B. Baranwal, I. Kapoor, D. Kumar, C. Singh, and R. Fröhlich

Abstract  

Three hexamethylenetetramine (HMTA) metal nitrate complexes such as [M(H2O)4(H2O-HMTA)2](NO3)·4H2O (where M=Co, Ni and Zn) have been prepared and characterized by X-ray crystallography. Their thermal decomposition have been studied by using dynamic, isothermal thermogravimery (TG) and differential thermal analysis (DTA). Kinetics of thermal decomposition was undertaken by applying model-fitting as well as isoconversional methods. The possible pathways of thermolysis have also been proposed. Ignition delay measurements have been carried out to investigate the response of these complexes under condition of rapid heating.

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Abstract  

New transition metal compounds of the general formula Ln(NO3)32[N4(CH2)6]nH2O, where Ln = La, Nd, Sm, Gd, Tb, Dy, Er, Lu, and n = 7-12, were obtained. The compounds and the gases evolved in the course of their thermal decomposition were characterised by thermogravimetric analysis. The measurements were carried out in air and argon environment in order to compare the intermediate products, final products and the mechanism of the thermal decomposition. The combined TG-MS system was used to identify the main volatile products of thermal decomposition and fragmentation processes of the obtained compounds.

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compounds commonly leads to nano-sized oxides and salts useful in various technical applications. As model ligands the hexamethylenetetramine (hmta) and 1,10-phenanthroline (phen) were chosen due to their specific properties: bulky shape and tetradentate

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Abstract  

New hexamethylenetetramine complexes of antimony and bismuth trichloride were synthesized through a solid phase reaction of hexamethylenetetramine and antimony or bismuth trichloride. The formula of the complex is MCl3(C6H12N4)2⋅H2O (M=Sb, Bi).The crystal structure of the complexes belongs to monoclinic system and the lattice parameters: a=1.249 nm, b=1.4583 nm, c=1.6780 nm andβ=91.78 for SbCl3(C6H12N4)2⋅H2O and a=1.3250 nm, b=1.3889 nm, c=1.7449 nm and β=98.94 for BiCl3(C6H12N4)2⋅H2O. Far-infrared spectra reveal that the antimony or bismuth ion is coordinated by the nitrogen atom of the hexamethylenetetramine. The thermal analysis also demonstrates the complex formation between the antimony or bismuth ion and hexamethylenetetramine. The intermediate and final residues in the thermal decomposition process have been analyzed to check the pyrolysis reaction.

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Abstract  

The influence of pressure on the polycondensation reaction between novolac resin (N) present in commercially available moulding compounds and hexamethylenetetramine (HMTA) was studied up to 80 bars under air and in an inert atmosphere. For a low HMTA content (N/HMTA=98/2 mass ratio) high pressure enables the detection of two successive curing reactions. With increasing HMTA content the peak due to the first curing reaction becomes less pronounced at high pressure, while the enthalpy of the second increases. In an inert atmosphere both curing reactions are well observable even at ambient pressure and for lower HMTA content take place at lower temperatures, as expected. For the sample with N/HMTA=98/2 the curing reaction was followed using TG-MS.

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Introduction Hexamethylenetetramine (HMT, Hexamine, Urotropine) is an antibacterial agent widely used for the treatment of urinary tract infections [ 1 ], which is also frequently used in chemical synthesis, chemical industry

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Journal of Thermal Analysis and Calorimetry
Authors: Suzana Samaržija-Jovanović, Vojislav Jovanović, Sandra Konstantinović, Gordana Marković, and Milena Marinović-Cincović

resins with hexamethylenetetramine (HMTA, Resin 1), melamine (M, Resin 2), and ethylene urea (EU, Resin 3) including nano-SiO 2 was investigated by non-isothermal thermo-gravimetric analysis (TG), differential thermal gravimetry (DTG), and differential

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Abstract

The dinitramide salts of ammonia (ADN), hexamethylenetetramine (HDN), potassium (KDN), and sodium (NaDN) showed a linear relationship between the DSC rate of decomposition at the peak maximum and the DEA tanδ value at the low temperature transition peak. As the cation basicity increased in the series ADN<HDN<KDN<NaDN, there was an increase in the low temperature transition peak, the energy barrier for relaxation, and the decomposition peak temperature, and a decrease in the tanδ value at the low temperature transition peak, specific heat capacity, and the rate and enthalpy of decomposition. The more basic salts were more thermally stable (i.e., higher decomposition temperature) and less energetic (i.e., lower enthalpy of decomposition). The more internal free volume (disorder) present in these salts, the higher the rates of relaxation and decomposition. Five aluminum powders of different surface areas were analyzed by DSC in platinum sample pans, and it was found that the enthalpy and rate of oxidation increased as the particle size of Al decreased while the enthalpy of the Al melt decreased. TG showed a two-step weight gain in the oxidation of Al with plateaus in the 650 and 1130°C regions and the percent weight gain increased as the particle size of Al decreased. Variable DSC and TG heating rate studies showed that the activation energies for the first step in the oxidation process increased as the particle size of Al increased.

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Abstract  

On the basis of the theory of thermokinetics proposed in the literature, a novel thermokinetic method for determination of the reaction rate, the characteristic parameter method, is proposed in this paper. Mathematical models were established to determine the kinetic parameters and rate constants. In order to test the validity of this method, the saponifications of ethyl benzoate, ethyl acetate and ethyl propionate, and the formation of hexamethylenetetramine were studied with this method. The rate constants calculated with this method are in agreement with those in the literature, and the characteristic parameter method is therefore believed to be correct.In the light of the characteristic parameter method, we have developed further two thermo-kinetic methods, the thermoanalytical single and multi-curve methods, which are convenient for simultaneous determination of the reaction order and the rate constant. The reaction orders and rate constants of the saponifications of ethyl acetate and ethyl butyrate and the ring-opening reaction of epichlorohydrin with hydrobromic acid were determined with these methods, and their validity was verified by the experimental results.

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, Cesáro , A , Delben , F . Thermodynamic data for the water-hexamethylenetetramine system . J Phys Chem . 1971 ; 75 : 23 3633 – 3635 . 10.1021/j100692a027 . 6. Barone , G

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