含氟硫酸体系HEH/EHP萃取铈(Ⅳ)的动力学研究

采用层流恒界面池法研究了2-乙基己基膦酸单2-乙基己基酯(HEH/EHP)萃取含氟复杂硫酸体系中铈(Ⅳ)的动力学。考察了搅拌速度、水相金属离子浓度、萃取剂浓度、酸度和温度对萃取速率的影响。试验结果表明:萃取反应为一级反应,萃取反应的正向表观活化能为50.8 kJ·mol-1,属于化学反应控制。试验得到萃取动力学方程为R=k[Ce(HF)(HSO4-)3+]1.05[H2A2]2.07[H+]-2.43,并探讨了反应机制。     

2－乙基己基膦酸单（2－乙基己基）酯从盐酸溶液中萃取Ga（Ⅲ）的机理

２－乙基己基膦酸单（２－乙基己基）酯从盐酸溶液中萃取Ｇａ（Ⅲ）的机理赵经贵，邢美君，刘宏（黑龙江大学化学系哈尔滨１５００８０）关键词溶剂萃取，镓，乙基己基膦酸单（乙基己基）酯２－乙基己基膦酸单（２－乙基己基）酯（Ｐ５０７，ＥＨＰ）在稀有元素、有色金属...     

HEH(EHP)萃取稀土元素时萃取动力学行为的递变规律

采用恒界面池法研究了2-乙基己基2-乙基己基膦酸[HEH(EHP),P~5~0~7]在盐酸介质中萃取稀土元素时萃取动力学行为的递变规律,讨论了稀土元素分配比(D)和分离因数(β)随时间变化的规律,并测算出正向萃取速率常数(k~f)和逆向萃取速率常数(k~b).发现了萃取动力学中萃取速率常数的"四分组效应","斜W效应"和"钆断"现象,提出利用动态萃取体系分离稀土元素     

金属萃取平衡与软-硬酸碱规则

软硬酸碱规则从宏观角度描述化合物的形成及性质,在配合物稳定性的判断方面有广泛应用.前文^[1]报道了萃取速率常数与金属离子的软硬酸碱强度的关系,本文研究了萃取平衡常数与金属离子的软硬酸碱强度的关系.     

二(2,4,4-三甲基戊基)膦酸在中空纤维膜器中萃取镱、铒及传质研究

中空纤维膜萃取技术是将液液萃取过程与膜过程相结合的新型分离技术．二（２,４,４三甲基戊基）膦酸（ＨＢＴＭＰＰ,ＨＬ）萃取稀土及其它高价金属离子时所需水相酸度低,反萃容易,加之空间位阻等因素,很可能成为优于２乙基己基膦酸单２乙基己基酯（ＨＥＨ／...     

EHEHPA萃取Co(Ⅱ)的动力学和机理的研究

本工作研究了2-乙基己基膦酸单2-乙基己基酯(即EHEHPA)从醋酸醋酸钠缓冲介质中萃取Co(Ⅱ)的动力学和机理。萃取反应在改进的恒界面池中进行,并建立了连续、自动测量萃取动力学数据的研究系统。在动力学坪区测定了一系列初始萃取速率和反萃速率,比界面积和表面活性剂等对萃取速率的影响表明化学反应发生在液液界面,低于30℃时的表观活化能为82kJ·mol^-1,高于30℃时为31kJ·mol^-1,宽的组分浓度变化也会引起传质控制过程的转变。由此可以认为:EHEHPA萃Co(II)的动力学过程在萃取速率较低时为化学反应控制,随着反应速率的加快转变为组分在界面膜的扩散控制。     

HEH/EHP在中空纤维膜器中萃取钕、钐及传质研究

２－乙基己基膦酸单２－乙基己基酯（ＨＥＨ／ＥＨＰ,ＨＬ）是广泛用于稀土分离湿法冶金的有效萃取剂［１～３］．未氨化的ＨＥＨ／ＥＨＰ在中空纤维膜（ＨＦＭ）中萃取稀土元素的机理和控制模式已有报道［４,５］,但未氨化的ＨＥＨ／ＥＨＰ对轻、中稀土的萃取能力较弱...     

2-乙基己基膦酸单(2-乙基己基)酯对两价金属离子的萃取平衡

本文报导用2-乙基己基膦酸单(2-乙基己基)酯在煤油溶剂中萃取Sn(II),Pb(II), Zn(II)和Cd(II)等的平衡, 应用斜率法研究了萃取平衡; 合成了与Zn(II)和Pb(II)固体萃合物, 在元素分析和有关离子分析的基础上结合最小二乘法线性回归探讨了萃取机理及有关萃合物组成; 考察了在加入三辛基氧化膦(TOPO)时, 2,乙基己基膦酸单(2-乙基己基)酯对金属离子萃取性能的影响.     

萃取色谱分离—原子发射光谱测定超高纯氧化铥,氧化镱和氧化镥中痕…

用２－乙基己基膦酸单２乙基己酯萃取色说分离－原子发射光谱测定超高纯Ｔｍ２Ｏ３，Ｙｂ２Ｏ３，Ｌｕ２Ｏ３中痕量稀土杂质，可用于纯度为９９．９９９９％－９９．９９９９９％Ｔｍ２Ｏ３，Ｙｂ２Ｏ３，ｌＵ２ｏ３的纯分分析，１４个稀土杂质的回收率在６７％－１３３％之间；相对标准偏差５．１％－２３．２％，分离周期１０－１３ｈ。     

含P507微胶囊萃取水相中稀土的迁移行为

分别用乙基纤维素和海藻酸钙作为膜材，将Ｐ５０７（２－乙基己基鳞酸单２－乙基己基酯）微胶囊化。将这两种含萃取剂的微胶囊用于萃取Ｌａ３＋、Ｎｄ３＋和Ｌｕ３＋，可以将这些离子富集于微胶囊内。由于固体膜对芯材固定化和对离子的阻障作用，使萃取的传质过程发生了变化。以渗透系数来比较三种离子的传质速度，改变原料液的ｐＨ，可使离子的渗透系数改变，从而增大离子间渗透系数的差值。用６ｍｏｌＬ－１的ＨＣｌ对微胶囊内稀土离子进行反萃取，可以定量地富集稀土。     

Benzoylation of deactivated compounds of the thiophene and furan series with phenyldichlorocarbenium tetrachloroaluminate

The reactions of benzotrichloride with methyl and ethyl esters and nitriles of 2-thiophenecarboxylic and 2-furancarboxylic acids, with 2-acetylthiophene, 2-acetylfuran, and 2-thiophenaldehyde in the presence of an excess of anhydrous aluminum chloride have been studied. The phenyldichloromethyl group enters into position 4 of the thiophene and position 5 of the furan ring and on treating the reaction mixture with water is converted to benzoyl group.Dedicated to Professor M. A. Yurovskaya on her Jubilee.N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences (RAN), Moscow 117913 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3. pp. 315–323, March, 2000.     

H2NNO2裂解与重排反应的理论热力学动力学研究

硝胺化合物的N—N键断裂和硝基-亚硝基重排(>N—NO_2→>N—ONO)是一类重要的化学反应。最近Golden等重新测定了DMNA[(CH_3)_2NNO_22]消失的速度常数,认为其分解应包括N—N键断裂和硝基-亚硝基重排后的再分解等过程,并得到分子束实验的确认,但理论研究尚不多见。Melius和McKee等都曾对该类体系进行过量化计算,但结果并不令人满意。Saxon等取其模型体系H_2NNO_2进行量化计算,似可定性说明其断裂、重排     

自由基HO2与C2H2反应势能面的理论研究

应用量子化学从头计算和密度泛函理论(DFT)对HO2+C2H2反应体系的反应机理进行了研究.在B3LYP/6-311G**和CCSD(T)/6-311G**水平上计算了HO2+ C2H2反应的二重态反应势能面.计算结果表明,主要反应方式为自由基HO2的H原子和C2H2分子中的C原子结合,经过一系列异构化,最后分解得到主要产物P1 (CH2O+ HCO).此反应是放热反应,化学反应热为-321.99 kJ·mol-1.次要产物为P2 (CO2 +CH3),也是放热反应.     

Some further observations on the systems cellulose/trifluoroacetic acid/CH2Cl2 and cellulose triacetate/TFA/CH2Cl2

There is little or no trifluoroacetylation of cellulose dissolved in TFA-CH₂Cl₂ admixtures. Both cellulose and cellulose triacetate (CTA)are slowly degraded in the solvent. Cellulose forms a mesophase as low as 4%(w/w)concentration, but CTA has a much higher critical concentration, 20% (w/w), in TFA-CH₂Cl₂. The cellulose behaves as a rigid rod in TFA-CH₂Cl₂ (70/30v/v) and its persistence length calculated using the lattice model approximates its chain length, presumably due to extensive interaction with the solvent. As expected, due to low polymer-solvent interactions, the persistence length of CTA in TFA-CH₂Cl₂ is only one-fourth the chain length.     

Bioscillation and Birhythmicity in the H_2O_2-KSCN-CuSO_4-NaOH System

Two kinds of different mechanistic oscillations can be displayed in the H_2O_2-KSCN-CuSO_4-NaOH system. One discovered by this study is the pH oscillation in a continuous flow stirred tank reactor(CSTR) resulting from the oxidation of KSCN. The other is the oscillation of H_2O_2 decomposition in both CSTR and batch reactors(reported by Orbáin in 1986). Under appropriate experimental conditions, the system exhibits a birhythmicity in a CSTR. Two different pH oscillations are reported here. The pH oscillations which accompany the decomposition of H_2O_2 exist in the batch reactor and the CSTR at a high flowrate, but the pH oscillations in a CSTR at a low flowrate originates from proton positive and negative feedback in the oxidation of KSCN. The oscillation of non-catalyzed oxidation of KSCN by hydrogen peroxide in a CSTR can be found. Also we have observed whether Cu~(2+) exists or not in the batch system, the pH increases to near neutral ultimately after pH drops twice.     

Synthesis and Structure of 1- and 2-Isomers of (Trimethoxysilylmethyl) and (Silatranylmethyl)benzotriazole

We have synthesized 1- and 2-(trimethylsilylmethyl)- and 1- and 2-(trimethoxysilylmethyl)benzotriazoles by reaction of 1,2,3-benzotriazolylsodium with trimethyl- or trimethoxy(chloromethyl)silane. We obtained 1- and 2-(silatranylmethyl)benzotriazoles by transesterification of the latter with triethanolamine.     

Effect of CO2 adsorbents on the Ni-based dual-function materials for CO2 capturing and in situ methanation

The present work studied the effect of different carbon dioxide (CO₂) adsorbents on Ni-based dual-function materials (DFMs) for the development of carbon capture and on-site utilization in a reactor at isothermal condition. The DFMs containing Ni functioning as a methanation catalyst with various CO₂ adsorbents (i.e., CaO, MgO, K₂CO₃, or Na₂CO₃) were prepared on γ-Al₂O₃ through sequential impregnation. The result indicated that Ni-Na₂CO₃/γ-Al₂O₃ had the highest methanation capacity (i.e., 0.1783 mmol/g) and efficiency (i.e., 71.09%) in the CO₂ adsorption–methanation test. The CO₂ uptake and the subsequent methanation capacity of the Ni-Na₂CO₃/γ-Al₂O₃ increased to more than 24 times and more than 17 times, respectively, compared to Ni/γ-Al₂O₃. The high methanation capacity was correlated to its highest amount of weak basic sites, substantial CO₂ capture capacity and capture/release efficiency, and reactivity to H₂ at a lower temperature, supported by CO₂-TPD, TGA analyses for adsorption or adsorption–desorption at the isothermal condition, and H₂-TPRea, respectively. A continuous cyclic CO₂ adsorption–methanation was performed by using the Ni-Na₂CO₃/γ-Al₂O₃ and Ni-CaO/γ-Al₂O₃, showing that the CO₂ adsorption capacity was stabilized from third cycle onward, whereas the methanation capacity was stabilized at all cycles, indicating the high stability of the DFMs for both CO₂ adsorption and subsequent methanation. This work demonstrated successful synthesis of the Ni-based, low-cost, and stable DFMs with the ability to produce methane via the direct capture of CO₂.     

Investigation of the Addition of Benzenethiol to p-Chlorophenylphenylacetylene

The addition of benzenethiol to p-chlorophenylphenylacetylene results in the formation of a mixture of two pairs of diastereomeric (E)- and (Z)-1-p-chlorophenyl-2-phenyl-1-phenylthioethylenes (1 and 2) and (E)- and (Z)-1-p-chlorophenyl-2-phenyl-2-phenylthioethylenes (3 and 4). The configurations of these compounds have been established by ¹ H NMR studies, by their preparation from benzyl p-chlorophenyl ketone and p-chloro-benzylphenyl ketone, and by the oxidation of the thioethylenes 1, 2, 3, and 4 to the corresponding sulphonylethylenes 5, 6, 7, and 8, respectively.     

CaO对Cu-ZnO-ZrO_2催化CO_2加H_2合成甲醇性能影响

用CaO作为改性助剂,采用并流共沉淀法制备了CuO∶ZnO∶ZrO_2为5∶4∶1(物质的量比),CaO添加量为0、1%、2%、4%、8%、16%(摩尔分数)的六组催化剂。用X射线衍射(XRD)、微商热重(TG-DTG)、傅里叶红外(FT-IR)、N2吸附脱附(BET)、X射线光电子能谱(XPS)、氢气程序升温还原(H_2-TPR)、CO_2程序升温脱附(CO_2-TPD)、NH_3程序升温脱附(NH_3-TPD)对催化剂进行了表征。用自制固定床评价了催化剂活性。结果表明,添加CaO后,催化剂路易斯酸性和表面碱性增强;催化剂母体中高温碳酸盐含量增加,热稳定性增强,CuO颗粒粒径变小,Cu-Zn协同作用增强,Cu比表面积增大,分散性变好。催化剂活性受到表面酸碱性、铜比表面积、Cu-Zn协同作用和铜分散性共同影响。当CaO为2%时,铜比表面积为79.3 m2/g、铜分散度为34.8%、CO_2转化率为24.55%、甲醇选择性为19.01%、甲醇收率为0.044 g/(gcat·h),催化剂活性最好。过量CaO占据催化剂孔道和覆盖表面活性位,使催化剂路易斯酸性和表面碱性过强,CuO与H_2有效接触减少,CO_2难以脱附,催化活性下降。因此,适量CaO(2%)添加可促进CO_2加氢反应合成甲醇。     

2-Polyfluoroalkylchromones. 6. Synthesis of substituted 2-morpholino-2-trifluoromethylchroman-4-ones

Morpholine adds smoothly at the double bond of substituted 5- and 8-nitro-2-trifluoromethylchromones to form the corresponding 2-morpholino-2-trifluoromethylchroman-4-ones. 6-Methoxy-5-nitro-2-trifluoromethylchromone adds also benzylamine, whereas 7-methoxy-8-nitro-2-trifluoromethylchromone undergoes ring opening under the action of benzylamine to give 3-benzylamino-4,4,4-trifluoro-1-(2-hydroxy-4-methoxy-3-nitrophenyl)but-2-en-1-one.