3,6-二肼基-1,2,4,5-四嗪的热行为、比热容及绝热至爆时间

利用差示扫描量热法(DSC)、热重-微商热重法(TG-DTG)研究了3,6-二肼基-1,2,4,5-四嗪(DHT)的热行为, 其分解过程可分为两个放热的分解过程, 且热分解反应的表观活化能分别为154.8和123.4 kJ·mol-1, 指前因子分别为1016.63和109.48 s-1. DHT热爆炸的临近温度为426.10 K. 同时, 利用微量热法和理论计算方法研究了DHT的比热容, 298.15 K时的标准摩尔比热容为183.61 J·mol-1·K-1. 计算获得了DHT的绝热至爆时间为263.84-297.58 s之间的某一值.     

肼对热分解法制氧化钇比表面积的影响

肼对热分解法制氧化钇比表面积的影响吴介达＊陆世鑫王振华王晔明（同济大学化学系上海２０００９２）（上海跃龙有色金属有限公司上海）关键词氧化钇，肼，比表面积１９９６－０９－２３收稿，１９９７－０４－１８修回上海市自然科学基金资助课题氧化钇是一种需求量大、...     

硫酸铈水合物的热分解行为及动力学研究

利用TG—DTA和DSC手段研究了Ce(SO_4)_2·4H_2O的热分解行为。由TG—DTA曲线经Freeman法求出了热分解反应的活化能及反应级数,由DSC曲线测定了分解反应的脱水焓及分解焓值。通过化学分析、X射线物相分析及磁矩测量等方法表征了分解产物。     

1-氨基-1-肼基-2,2-二硝基乙烯（AHDNE）的非等温分解动力学，比热容和绝热至爆时间研究

利用DSC和TG/DTG法研究了1-氨基-1-肼基-2,2-二硝基乙烯（AHDNE）热分解行为及分解动力学,第一热分解过程的动力学方程为： ,其热爆炸临界温度为98.16 ºC。同时,利用微量热法测定了AHDNE的比热容,298.15K时的标准摩尔比热容为211.86 J•mol-1•K-1。计算得到了AHDNE的绝热至爆时间为59.21 s。AHDNE是不稳定的,其热稳定性远低于母体化合物FOX-7。     

不同晶相碳化钨的肼分解性能及其CO微量吸附量热研究

以WO3为前驱体考察了CH4/H2混合气氛下程序升温反应制备碳化钨的晶相转变过程,比较了不同晶相碳化钨催化剂的肼分解活性,并以CO为探针分子采用微量吸附量热技术研究了碳化钨晶相转变过程中催化剂的表面活性位. 结果表明,随W2C晶相的生成,催化剂对CO的吸附活化能力逐渐增强,纯相W2C表现有最好的肼分解活性. 当制备温度高于750 ℃时,样品表面形成的积炭抑制了碳化钨的催化性能. 表面洁净的WC在肼分解反应中具有优于W2C的类贵金属催化特性.     

含肼钒盐热分解制备三氧化二钒

近年来,低价(或混合价)金属氧化物和超细化合物在磁、电、光、色等方面的特性,越来越受到人们的关注。V_2O_3可作催化剂,常用H_2还原V_2O_5或NH_4VO_3来制备。 前文曾用钨酸肼和含肼铝盐热分解,制得了蓝色氧化钨(WO_(2.90))和细颗粒α-Al_2O_3,在此基础上,本文报道用含肼钒盐热分解制备V_2O_3并对它的某些物理性能进行了测定。 1 实验部分     

Mg2NiH4对高氯酸铵热分解过程的影响

采用置换-扩散法制备了储氢材料Mg2NiH4, 用XRD, ICP和DSC-TG方法对其结构进行了表征. 用热分析法(DSC)研究了Mg2NiH4对高氯酸铵(AP)热分解过程的影响. 研究结果表明, Mg2NiH4对AP热分解过程有较大影响. Mg2NiH4可以显著促进AP的低温热分解过程, 降低高温热分解温度, 使DSC表观分解热明显增大. 随着加入量的增加, Mg2NiH4对AP热分解的催化促进作用增强, 当Mg2NiH4加入的质量分数为30％时, DSC表观分解热最大. 吸氢量越大, 储氢材料对AP的催化促进作用越强. Mg2NiH4催化促进AP分解过程的作用机理为: Mg2NiH4分解释放的H2及Mg和Ni与AP分解产物发生反应.     

非等温热分析法研究白藜芦醇及其苷的熔点、热稳定性及分解动力学

首次采用差示扫描量热法(Differential scanning calorimetry,DSC)和热重法(Thermogravimetry,TG)在氮气气氛下对白藜芦醇和白藜芦醇苷进行非等温热分析,采用Van't Hoff方程求得其纯度和熔点,并使用积分Coats-Redfern法、微分Achar法以及Malek法3种热分析动力学方法对热重实验数据进行分析,推断两种天然产物快速热分解阶段的最概然机理函数,并求得相应的动力学参数——表观活化能Ea和指前因子A。研究表明,白藜芦醇及其苷的纯度分别为99.76%和98.90%,熔点分别为257.09℃和198.79℃;白藜芦醇的热分解发生在220~468℃之间,失重率为46.69%;白藜芦醇苷在198~369℃之间发生分解,主要是糖苷键断裂引起的分解失重,失重率为37.47%;白藜芦醇的热分解为化学反应控制机制,符合反应级数方程,反应级数n=2;白藜芦醇苷的热分解为三维扩散控制机制,符合Z.-L.-T.方程;根据白藜芦醇及其苷的热分解动力学参数,推断二者在室温(25℃)下的贮存期分别为3年和4~5年,糖苷键的引入使白藜芦醇苷比白藜芦醇有更长久的贮存期。     

气相色谱法研究金属草酸配合物的热分解

用气相色谱(GC)、热重(TG)和差示扫描量热(DSC)法研究金属草酸配合物的热分解已有报道。本文用GC法研究两种合成的草酸配合物[三水合三草酸合铁(Ⅲ)酸钾和三水合三草酸合钴(Ⅲ)酸钾]的热分解反应,配合TG,DSC测试数据,探讨了分解机理,并用微机编程序计算获得反应级数和活化能。     

脯氨酰肼小分子催化的环己酮的直接α-硫代反应

研究了脯氨酰肼有机小分子催化环己酮的直接α-硫代反应. 考察了3种不同硫代试剂、9种溶剂、6种脯氨酰肼催化剂等对反应的活性和收率的影响. 结果表明, 硫代试剂、溶剂及催化剂的结构对反应的活性和反应收率均有较大的影响. 在优化条件下, 即以邻苯二甲酰亚胺为硫代试剂, 甲苯为溶剂, 脯氨酰肼1和4催化的环己酮的硫代反应活性比较高, 室温反应12 h, 收率达98%. 脯氨酰肼催化该类反应条件温和, 操作简单, 在药物合成中具有一定的应用潜力.     

Thermal hazard analysis of mixed system of hydrazine and nitric acid

In order to obtain a better understanding of the thermal hazard of hydrazine and nitric acid mixtures which are used in plutonium and uranium recovery by extraction (PUREX) process during recycling of spent fuel in nuclear plant, DSC was carried out for the mixed system made by the small scale reaction calorimeter super-CRC in various conditions. It was found that the concentration of the nitric acid has a strong influence on the thermal behavior of the mixed system, and hydrazine nitrate which is formed in the reaction in the mixture was determined by DSC with FTIR analysis.     

Systematic synthesis of phthalimide-protected unsaturated hydrazine heterocycles

A four-step route for the synthesis of novel phthalimide-protected hydrazine heterocycles that include a C?C double bond in the cycle was developed. Phthalimide-protected Boc-hydrazine was used as a starting material, which was alkylated with bromoalkenes in mild conditions. Further steps involved Boc-deprotection and second alkylation with bromoalkenes. Finally, the heterocycles were produced by ring-closing metathesis. This route allows access to these versatile building blocks without using electrophilic amination or nitrosylation, therefore, significantly reducing environmental and safety concerns. Phthalimide-protected heterocycles can be derivatized further by modifying the carbon–carbon double bond and by deprotection and subsequent functionalization of the primary amino group. During the current research, various five- to seven-membered hydrazine heterocycles and numerous novel intermediate compounds were synthesized and thoroughly characterized.     

Determination of hydrazine in polyvinylpyrrolidone by derivatization and square wave voltammetry

A rapid and precise method has been developed for the determination of hydrazine in polyvinylpyrrolidone (PVP). Hydrazine is converted to salicylaldazine by reaction with salicylaldehyde. After extraction, the azine is reduced at –1.56 V versus the SCE at the hanging drop electrode. Detection is accomplished using square wave voltammetry and comparison to an external salicylaldazine standard. The described procedure can detect as little as 70 ng/g hydrazine in PVP.     

分光光度法测定水合肼技术性因素的研究

针对现行肼测定的标准分析方法(水质肼的测定-对二甲氨基苯甲醛分光光度法HJ674-2013)影响测定质量的因素,以实际测定为依据,从分析方法和统计学方法出发,研究和论述了校准曲线的建立、方法的测定范围、被测定样品的取样方式等几个方面,对分析测定及测定结果造成的影响。结果表明,分析方法的校准曲线建立方式会对校准曲线的质量和精密度产生很大影响,最终将影响到样品测定的准确性;测定范围将会影响到方法的适用性;方法中不正确的取样方式,不仅影响到样品测定的准确性,同时也使溯源性受到影响。本文给出的建议,可对方法的应用和修订提供技术支持。     

Thermal properties of hydrazine in nitric acid solution

Since some combustible, oxidative and reductive chemicals are used in the extracting process in the nuclear reprocessing plant the process has potential hazards of a fire and explosion due to the undesired reaction. In this study to obtain a better understanding of the thermal properties of hydrazine in nitric acid solution which is used for preventing the oxidation of extracted plutonium, thermal analysis was carried out for the mixtures in various conditions. From the results of DSC it was revealed that the vessel material has an influence on the thermal decomposition of hydrazine. It was also found that hydrazine reacted with nitric acid in an autocatalytic manner, and concentration of nitric acid has a strong influence on the thermal hazard of hydrazine and nitric acid mixtures.     

Thermal hazard analysis of hydrazine and nitric acid mixtures

Summary In order to obtain a better understanding of the thermal hazard of hydrazine and nitric acid mixtures which are used in PUREX (Plutonium and Uranium Recovery by Extraction) process during recycling of spent fuel in nuclear plant, DSC and small scale reaction calorimetry super-CRC were carried out for the mixtures in various conditions. From the DSC analysis the apparent activation energy of hydrazine monohydrate in SUS 303 crucible was determined to be 96 kJ mol^-1. The mixing hazard of hydrazine monohydrate with nitric acid was measured with super-CRC and the results suggested that the concentration and the mass of nitric acid had a strong influence on the mixing heat of reaction of the system.     

Determination of hydrazine and sulphite in the presence of one another

A simple titrimetric method has been developed for determination of sulphite and hydrazine in compounds containing both. The sulphite is oxidized quantitatively to sulphate by iodine in acid medium, and the sum of hydrazine and sulphite is determined by Andrews titration with iodate. The hydrazine content is found by difference.     

The low temperature synthesis of metal oxides by novel hydrazine method

The hydroxide, oxalate and citrate precursors of the metal oxides such as γ-Fe₂O₃, (MnZn)Fe₂O₄, Cu(K)Fe₂O₄, BaTiO₃, La(Sr)MnO₃, La(Sr)AlO₃, La/Gd(Ca/Ba/Sr)CoO₃, and anatase TiO₂ on modifications with the hydrazine decompose at low temperatures give single phase oxides of superior properties, while the complexes without such modification require higher temperatures for achieving the phases. The hydrazine released at lower temperatures reacts with the oxygen in the atmosphere, N₂H₄+O₂→N₂+2H₂O; ΔH=−625 kJ mol⁻¹, and liberates enormous energy that is sufficient for the oxidative decomposition of the complexes now devoid of hydrazine. Such extra energy is not available in the case of the precursors without such modifications. The reaction products of hydrazine oxidation provide desired partial pressure of moisture needed for the stabilization of γ-Fe₂O₃. Also, the nitrogen that is formed in the reaction of hydrazine with oxygen gets trapped in the lattice of TiO₂ giving yellow color nitrogen doped TiO_2−xN_x photocatalyst. Thus, hydrazine method of preparation has many advantages in the preparation of metal oxides of superior properties.