N,N′-二乙(甲)基-N,N′-二苯基脲对铀(VI)和钍(IV)萃取行为的研究

目前国际上一般采用磷酸三丁酯(TBP)作为铀的萃取剂。TBP对铀有较强的萃取能力,但其耐辐照能力较差。酰胺的理化性质类似于TBP,与TBP相比降解产物易除去,“可完全燃烧”等优点而被认为是一种能取代应用于核燃料后处理的有前途的萃取剂。本文以二甲苯或三氯甲烷     

N、N'-二乙基-N、N'-二苯基脲的萃取性能和二硝酸二(N、N'-二乙基-N、N'-二苯基脲)合铀酰(Ⅱ)配合物的合成、结构研究

O引言 铀和钍燃料后处理广泛采用三丁基磷酸酯(TBP)作为萃取剂来分离铀和钍.然而在辐照下,TBP的降解产物二丁基磷酸酯(DBP)和一丁基磷酸酯(MBP)对裂变元素如锆和铌有较强的配位能力.     

N,N,N＇,N’-四丁基丁二酰胺萃取Tb（Ⅲ）的研究

国内外在四取代双酰胺类萃取剂萃取铀（Ⅳ）、钍（Ⅳ）的性能研究方面已经做了大量工作，但对核废料中共存稀土元素的萃取研究较少。本文合成了N，N，N’，N’-四丁基丁二酰胺（TBSA），详细研究了其萃取Tb（Ⅲ）的性能。     

二硝酸 N ,N ''''-二癸酰基哌嗪合铀酰髤配合物的合成和晶体结构

0引言酰胺类萃取剂合成容易,燃烧完全,不产生二次污染[1￣4],被认为是有应用前景的萃取剂。N,N-二取代烷基酰胺能分离锕系和镧系元素[5],是核燃料后处理中可能取代TBP的新型萃取剂。N,N'-二癸酰基哌嗪(D D PEZ)是含2个酰基的新型酰胺萃取剂,对铀具有良好的萃取性能[6,7],能明显地消除萃取过程中的三相问题,这对核燃料水法后处理非常重要。根据D D PEZ萃取实验结果和光谱数据对该配合物的组成和结构[6,7]进行了推测,本文则进一步确定了该配合物的晶体结构为U O2(D D PEZ)(N O3)2。配合物的结构对称分布,2个D D PEZ分子采取了较…     

P350-聚三氟氯乙烯萃取色层分离分光光度法测定矿石中微量铀

萃取色层法是将溶剂萃取和色层分离相结合的新型分离方法,它兼有溶剂萃取和色层分离两种分离方法的优点,现已广泛应用到微量铀的分离测定中。通常采用的萃取剂有TBP、P350、P204、N263、TOPO等。其中P350是我国自己合成的萃取剂,它具有萃取能力强、分配系数大、选择性好等优点。本文应用P350-聚三氟氯乙烯萃取色层柱分离干扰元素,以5-Br-PADAP-磺基水杨酸-溴化十六烷基吡啶(CPB)为显色剂,分光光度法测定矿石中微量铀。经实践证明,该法简单快速,灵敏度较高,选择性较好,适用于矿石中微量铀的测定。     

氯化型N235-苯-盐酸混合体系萃取铀(Ⅵ)-偶氮氯膦Ⅲ-N235三元离子缔合物光度法测定微量铀

利用溶剂萃取,使铀同干扰离子分离,可提高测定铀的选择性。但是往往稀土、钍、钙、钒、铌、钽、锆、铪及钛等仍有严重干扰。T(?)Yamamoto等报导了用三正辛胺-苯-乙醇-盐酸体系萃取铀(Ⅵ),以偶氮氯膦Ⅲ(CPAⅢ)作显示剂测定海水中微量铀。我们在此基础上研究了国产N235(叔胺类萃取剂)-苯-盐酸体系中铀的萃取。发现在4N以上盐酸介质中能定量萃取铀,在4.5～6.5N盐酸介质中,能使铀有效地同稀土、钍、锆、铌、钽及钛等离子分离。然后在氯化型N235-苯-乙醇-盐酸体系中,加入CPAⅢ形成蓝绿色的铀(Ⅵ)-CPAⅢ-N235     

N1923从碱性氰化液中萃取金(Ⅰ)的研究

采用放射性同位素198Au示踪法研究了伯胺N1923和TBP从碱性氰化液中萃取金(Ⅰ),考察了酸化率、水相pH值、萃取剂浓度等对萃取率的影响,以及NaOH对载金有机相的反萃作用。结果表明,TBP含量大于20％,酸化的N1923与KAu(CN)2摩尔比值在11时,金能够完全被萃取。载金有机相可采用0.1mol·L-1的NaOH溶液定量反萃。机理研究表明,伯胺和TBP萃取Au(CN)2-,符合BC类协同萃取机理。当金浓度大于10g·L-1时,在萃取有机相中形成纳米级的聚集体。     

磷酸三丁酯萃取苯酚的研究

溶剂萃取法处理含酚废水一般选用醋酸丁酯.甲基异丁基酮和异丙醚等N,N,-二甲基庚基乙酰胺(N503)萃取酚已得到实际应用,但酮类水溶性较大,醋酸丁酯等萃取酚的分配系数不及取代酰胺类,常用萃取剂磷酸三丁酯(TBP)也具有良好的萃取脱酚性能,已有磷类萃取剂萃取酚的报道.本文考虑了TBP萃取苯酚的性能,通过在不同温度下分配比的测定,求得萃取反应的热力学函数.用斜率法.连续变量法研究了萃合物的组成,并根据IR和1H NMR讨论了萃取过程与萃合物的结构.     

溶剂萃取动力学的研究——Ⅲ.氯化铀酰在盐酸和磷酸三丁酯之间的传质过程

本文采用上升液滴法,研究了氯化铀酰在盐酸介质和磷酸三丁酯(TBP)之间的传质过程.在一定浓度的盐酸溶液中,TBP 萃取铀的速率与[U]和[TBP]_(0)~2成正比;反萃速率与[U]_(0)成正比,而与[TBP]_(0)成反比.在温度为20～40℃范围内分别测定了萃取和反萃反应的活化能,它们的差值与由萃取平衡分配比与温度关系测得的焓变相符.可以认为,萃合物 UO_2Cl_2·2TBP 的生成和离解都是分步进行的,中间产物是 UO_2Cl_2·TBP;萃取速率的控制步骤是 UO_2Cl_2·2TBP 的生成反应,而反萃速率的控制步骤是 UO_2Cl_2·TBP 的离解反应.     

纸上反相分配色谱中铀的协同萃取效应

溶剂萃取中采用混合萃取剂所产生的协同效应,已获得了广泛的研究.特别是以螯合萃取剂与中性萃取剂组成的协同萃取体系,更引起人们的重视.Cvjeticanin将纸上反相分配色谱用于协萃效应的研究.选用螯合萃取剂噻吩甲酰三氟丙酮(TTA)与中性磷类萃取剂磷酸三丁酯(TBP)、三辛基氧化膦(TOPO)或磷酸三辛酯(TOP)组成的混合萃取剂作固定相,研究了对铀、钍和稀土元素的协萃效应,并探讨了有关的协萃机理.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.