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The kinetic and thermal behaviour of the following compounds:
R-HN-CO-NH-(CH2)n-C6H4-SO2NH2
where R=3,4-dichlorophenyl, phenyl, cyclohexyl; n=0, 1, 2 were studied by TG and DTA techniques.
The compounds decompose in many steps; the last one corresponding to the burning of H2N–S–C6H4–C6H4–S–NH2 occurs with comparable reaction rates.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
Guerreiro C. T. R. Ribeiro C. A. Crespi M. S. Torres C. 《Journal of Thermal Analysis and Calorimetry》2002,67(2):419-424
Magnesium ion was reacted with 5,7-dibromo-, 5,7-dichloro-, 7-iodo-and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium
hydroxide medium under constant stirring to obtain (I) Mg[(C9H4ONBr2)2]·2H2O; (II) Mg[(C9H4ONCl2)2]·3H2O; (III) Mg[(C9H5ONI)2]·2H2O and (IV)Mg[(C9H4ONICl)2]·2.5H2O complexes. The compounds were characterized by elemental analysis, IR spectra, ICP, TG-DTA and DSC.
Through thermal decomposition residues were obtained and characterized, by X-ray diffractometry, as a mixture of hexagonal
MgBr2 and cubic MgO to the (I) compound at 850°C; cubic MgO to the (II), (III) and (IV) compounds at750, 800 and 700°C, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
K. Györyová V. Balek B. H. Behrens A. Matuschek A. Kettrup 《Journal of Thermal Analysis and Calorimetry》1997,48(6):1263-1271
The new zinc(II) complexes of general formula Zn(CH3CH2CH2COO)2· nL (whereL = caffeine, nicotinamide, theobromine;n=1 or 2) were prepared and identified.Thermal properties of these compounds were investigated by thermal analysis (TG/DTG, DTA, DSC/DDSC).Gaseous products of thermal decomposition were detected by IR spectroscopy and Mass spectroscopy. Final products of thermal decomposition were determined by X-ray powder diffraction patterns.This work was supported by the Slovak Ministry of Education Grant No. 1/3230/96. This financial support is gratefully acknowledged. 相似文献
5.
The thermal behavior and thermal decomposition kinetic parameters of podophyllotoxin (1) and 4 derivatives, picropodophyllin (2), deoxypodophyllotoxin (3), fl-apopicropodophyllin (4), podophyllotoxone (5) in a temperature-programmed mode have been investigated by means of DSC and TG-DTG. The kinetic model functions in differential and integral forms of the thermal decomposition reactions mentioned above for first stage were established. The kinetic parameters of the apparent activation energy Ea and per-exponential factor A were obtained from analy- sis of the TG-DTG curves by integral and differential methods. The most probable kinetic model function of the decomposition reaction in differential form was (1- a)^2 for compounds 1-3,2/3·a^-1/2 for compound 4 and 1/2(1-a)·[-In(1-a)]^-1 for compound 5. The values of Ea indicated that the reactivity of compounds 1-5was increased in the order: 5〈4〈2〈1〈3. The values of the entropy of activation △S^≠, enthalpy of activation △H^≠ and free energy of activation △G^≠ of the reactions were estimated. The values of △G^≠ indicated that the thermal stability of compounds 1-3 with the samef(a) was increased in the order: 2〈3〈1. 相似文献
6.
可可碱、咖啡因、茶碱的滤纸基质室温燐光测定 总被引:2,自引:0,他引:2
以快速定量滤纸为基质 ,用KI NaAc为重原子微扰剂 ,建立了测定痕量可可碱、咖啡因、茶碱的滤纸基质室温磷光 (PS RTP)分析法。该法取样量少 ,线性范围宽 ,可可碱、咖啡因、茶碱的线性范围分别为 14 4~5 76 ;5 .4 4~ 6 99;7.2 1~ 36 0ng/斑点 ;检出限分别为 1 14、0 78、1 80ng/斑点。该方法用于巧克力中可可碱、茶叶中咖啡因、氨茶碱药片中茶碱的测定 ,操作简便快速 ,选择性好。标准回收率在 92 8%~ 10 6 %之间 ;相对标准偏差RSD <5 % 相似文献
7.
Dragoe N. Nakahara K. Xiao L. Shimotani H. Kitazawa K. 《Journal of Thermal Analysis and Calorimetry》1999,56(1):167-173
The thermal decomposition of methano-fullerene derivatives such as ethoxycarbonyl methano[60] fullerene and various isomers
of bis-(ethoxycarbonyl methano)[60] fullerene leads to new fullerene derivatives, which have been preliminary characterized.
The analysis of separated species was performed by UV-VIS, IR, H- and C-NMR, STM, FAB, LDI and MALDI-TOF MS spectroscopy.
One of the isolated phases is a C122 molecule with a dumbbell-like structure.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
建立了一种简单的同时分离测定生物碱样品中咖啡因、可可碱和茶碱3种有效成分的区带毛细管电泳法。采用未涂层石英毛细管(75μm i.d.×60 cm,有效长度50 cm),以20 mmol.L-1硼砂-4 mmol.L-1β-CD(pH 9.0)为运行缓冲液,压力(0.5 psi)进样5 s,运行电压16 kV,检测波长273 nm,温度25℃。在优化的实验条件下,3种生物碱的电泳谱图峰面积与其质量浓度在0.036~0.288 g.L-1呈良好线性关系(r≥0.998 4);方法的精密度、重复性和稳定性良好,其峰面积的RSD均不大于3.2%,其检出限均不大于2.7mg.L-1;加标回收率为97%~104%。该方法简单、快速、试剂消耗少,可用于生物碱样品中咖啡因、可可碱和茶碱的分离与测定。 相似文献
9.
Wacławska I. Pieczka A. Olkiewicz St. Żabiński W. 《Journal of Thermal Analysis and Calorimetry》1998,52(2):413-423
The thermal decomposition of axinite was studied by means of thermal, FTIR and X-ray methods. Dehydroxylation takes place
in a rather narrow temperature range, the maximum of the corresponding peak being at ca. 900°C. The decomposition products
are anorthite, rankinite and probably also small amounts of other, partly amorphous phases.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
The thermal decomposition reactions of calcitic dolomite were investigated. Simultaneous TG/DTG/DTA were applied under non-isothermal
conditions. From the recorded curves, the activation energies, pre-exponential factors and thermodynamic parameters of activation
were calculated for the two thermal decomposition steps.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
11.
Thermal Decomposition of Some Chemical Compounds Used As Food Preservatives and Kinetic Parameters of This Process 总被引:1,自引:0,他引:1
Thermal decomposition processes of selected chemicals used as food preservatives such as sodium formate, sodium propionate,
sodium nitrates(V and III) and sodium sulphate(IV) were examined by the derivatographic method. Based on the curves obtained,
the number of decomposition stages and characteristic temperatures of these compounds have been found. Mass decrements calculated
from TG curves ranged from 28.9% for sodium formate to 77.8% for sodium nitrate(V), while sodium sulphate showed a mass increment
of 5.6%. Kinetic parameters such as activation energy (E
a ), frequency factor (A ) and reaction order (n ) were calculated from TG, DTG and T curves. Sodium formate shows the highest values of E
a and A which amount to 171.7 kJ mol–1 and 5.8⋅1014 s–1 , respectively, while the lowest ones, E
a =28.2 kJ mol–1 and A =3.65⋅102 s–1 belong to sodium nitrate(V).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
高效液相色谱法对牦牛血浆与尿中嘌呤衍生物及肌酐含量的测定 总被引:1,自引:0,他引:1
建立了牦牛血浆及尿中的嘌呤衍生物及肌酐含量测定的HPLC/UVD方法.在室温条件下,以乙酸铵为流动相,分别以Lichrospher RP-C18 Merck(4.6×250 mm,5 μm i.d.)和5C18-AR-Ⅲ Waters(4.6×250 mm)为色谱柱,检测波长220 nm,流速1 mL/min,对尿囊素、尿酸、肌酐、黄嘌呤和次黄嘌呤进行了检测.方法检出限(LOD)为0.2 ~0.4 μmol/L,血样和尿样的加标回收率分别为81% ~103%、83% ~104%. 相似文献
13.
丙硫异烟胺的热稳定性及其热分解动力学 总被引:5,自引:0,他引:5
通过热重法研究了抗结核药物丙硫异烟胺的热稳定性, 计算了该药物的动力学参数并建立了热分解动力学方程. 用Kissinger和Ozawa-Flynn-Wall两种方法计算该药物热分解过程的活化能Ea=54.65 kJ·mol-1. 用Malek法推断该药物的动力学机理函数及指前因子A, 其结果分别为f(α)=α0.391(1-α)0.145, lnA=13.12. 此外, 用差热法测定该物质的熔点、摩尔熔化焓和摩尔熔化熵, 分别是414.09 K、23.21 kJ·mol-1和56.06 J·mol-1·K-1. 相似文献
14.
Mechanism of Thermal Decomposition of Barium Benzoate 总被引:4,自引:0,他引:4
Barium benzoate was synthesized in a hydrothermal reaction. The complex was characterized by elemental analysis, IR spectroscopy and X-ray powder diffraction. It was monoclinic and had a layered structure. The mechanism of thermal decomposition of the barium benzoate was studied by using TG, DTA, IR and gas chromatography-mass spectrometry. In a nitrogen atmosphere, the barium benzoate decomposed to form BaCO3 and organic compounds: mainly benzophenone, triphenylmethane, etc.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
15.
Pinheiro G. F. M. Lourenço V. L. Iha K. 《Journal of Thermal Analysis and Calorimetry》2002,67(2):445-452
This work refers to a study of the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine (HMX) by differential
scanning calorimetry (DSC) in non-isothermal conditions, with heating rates from1 to 25°C min−1. The influence of the heating rate, the particle and the sample size were verified. The activation energy was calculated
using the peak temperature shift method, proposed by Ozawa and a significant variation in the results was observed according
to the range of the used heating rates. As the heating rate was increased, different conversions and self-heating effects
were observed at the respective DSC peaks, indicating that the use of this method was inadequate and it may lead to incorrect
results, which, in turn, could explain the wide range of activation energy values published in literature. At lower heating
rates HMX decomposition occurs on the solid state and at higher ones decomposition occurs after melting practically at the
same temperature, which does not depend on the heating rate.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
柚皮苷的热稳定性及其热分析动力学研究 总被引:3,自引:0,他引:3
用TG-DTG/DTA方法研究了柚皮苷的热降解过程及热分析动力学. 热重分析结果表明该物质的失重过程分两步进行. 第一步为结晶水脱出, 其温度范围为343~545 K, 第二步为其分子骨架大规模降解, 其温度范围在545~857 K. 差热分析结果表明, 该物质的熔化温度为439.2 K. 使用Friedman和Ozawa-Flynn-Wall两种方法分别计算出该物质降解过程的活化能. 采用多步线性回归方法, 并参考常用的15种热解机理函数, 确定了柚皮苷热解过程最佳动力学模型为Fn-F2-F1. 相似文献
17.
Chomič J. Györyová K. Szunyogová E. Kováéová J. 《Journal of Thermal Analysis and Calorimetry》2004,76(1):33-41
Five new complex compounds of general formula Zn(Hsal)2·L2·nH2O (where Hsal=OHC6H4COO-, L=thiourea (tu), nicotinamide (nam), caffeine (caf), theobromine (tbr), n=2-4), were prepared and characterized by chemical analysis, IR spectroscopy and studied by methods of thermal analysis (TG/DTG,
DTA). It was found that the thermal decomposition of hydrated compounds starts with the release of water molecules. During
the thermal decomposition of anhydrous compounds the release of organic ligands take place followed by the decomposition of
salicylate anion. Zinc oxide was found as the final product of the thermal decomposition heated up to 800°C. RTG powder diffraction
method, IR spectra and chemical analysis were used for the determination of products of the thermal decomposition.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
丹酚酸B的热稳定性及其热分解动力学研究 总被引:5,自引:0,他引:5
用TG-DTG 方法研究了丹参的有效成分丹酚酸B 的热降解过程. 热重分析结果表明该物质的失重过程分两步进行. 笫一步为脱去吸附水, 其温度范围为305~373 K, 第二步为丹酚酸B 分子骨架大规模降解, 其温度范围在413~864 K. 用Friedman 和Ozawa-Flynn-Wall 两种方法分别计算出该药物降解过程中的三个阶段的活化能, 采用多步线性回归方法, 并参考常用的15 种热解机理函数, 确定了丹酚酸B 热降解过程最佳动力学模型为Fn-F2-F1. 相似文献
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20.
Decomposition of carbon tetrachloride in a RF thermal
plasma reactor was investigated in argon atmosphere. The net
conversion of CCl4 and the main products of its decomposition
were determined from the mass spectrometric analysis of outlet
gases. Flow and temperature profiles in the reactor were
calculated and concentration profiles of the species along the
axis of the reactor were estimated using a newly developed
chemical kinetic mechanism, containing 12 species and 34 reaction
steps. The simulations indicated that all carbon tetrachloride
decomposed within a few microseconds. However, CCl4 was partly
recombined from its decomposition products. The calculations
predicted 70\% net conversion of CCl4, which was close to the
experimentally determined value of 60\%. A thermodynamic
equilibrium model also simulated the decomposition. Results of the
kinetic and thermodynamic simulations agreed well above 2000 K.
However, below 2000 K the thermodynamic equilibrium model gave
wrong predictions. Therefore, application of detailed kinetic
mechanisms is recommended for modeling CCl4 decomposition under
thermal plasma conditions. 相似文献