等压法测定298.15K下LiCl-CaCl2-H2O体系的活度系数

电解质水溶液热力学性质的研究一直是一个很活跃的研究领域.对含锂水盐体系热力学性质的研究不仅对电解质水溶液理论,而且对盐湖锂资源的开放利用都有非常重要的意义.姚燕等对ＬｉＣｌＫＣｌＨ2Ｏ[1],ＬｉＣｌＭｇＣｌ2Ｈ2Ｏ[2],ＬｉＣｌＭｇＳＯ4Ｈ2Ｏ[3,4],ＬｉＣｌＬｉ2ＳＯ4Ｈ2Ｏ[5]体系多温下热力学性质进行了研究,应用Ｐｉｔｚｅｒ电解质水溶液理论模型进行处理,计算出ＬｉＣｌ在不同体系中,很大的浓度范围内的活度系数.但在盐湖卤水中,ＣａＣｌ2的存在很普遍.对ＬｉＣｌＣａＣｌ2混合物在水溶液中的热力学性质研究对理解ＬｉＣｌ在盐…     

LiCoO2的固相配位化学合成

目前商品化的锂离子电池大都采用ＬｉＣｏＯ2作为正极材料[1],工业上锂钴氧化物(ＬｉＣｏＯ2)多采用高温固相合成法生产,烧结时间长达24-48ｈ,制得的粉末粒度大分布范围广,形貌不规整[2]。溶胶 凝胶法前驱体的制备比较麻烦[3]。我们用固相配位化学反应法合成锂钴氧化物Ｌｉ ＣｏＯ2,操作简便兼具反应温度低、反应时间短、粒度分布均匀的优点[4,5]。本文采用氢氧化锂、乙酸钴和柠檬酸为原料,通过低热固相反应合成了Ｌｉ+与Ｃｏ2+达到分子级混合水平的前驱体、在400-800℃焙烧得ＬｉＣｏＯ2产品,通过热重/差热、Ｘ射线衍射、扫描电镜和粒…     

火焰原子吸收光谱法测定氧化铝中杂质元素

普通氧化铝中杂质元素主要有钠、钾、硅、铁、钙、镁、锌、锰、铜、锂、钙等。在国家标准[1] 中 ,Ｎａ2 Ｏ、Ｋ2 Ｏ的分析采用火焰光度计法 ,Ｆｅ2 Ｏ3 的分析采用比色法 ,ＺｎＯ的分析采用原子吸收光谱法。国家标准中没有Ｌｉ2 Ｏ的分析方法 ,文献 [2 ]介绍了Ｌｉ2 Ｏ的分析方法。这些元素的测定采用了不同的溶样方法和测定方法 ,手续多 ,时间长 ,而且使用了三种分析仪器。本文采用ＨＣｌ溶样 ,加消电离剂 ,用空气 乙炔火焰连续测定氧化铝中五种元素的含量 ,取得了满意的结果。1　试验部分1.1　主要仪器与试剂岛津ＡＡ 6 80 0型原子吸收分…     

萤石中CaF2的快速测定

萤石又称氟石 ,在钢铁工业中主要用于转炉或电炉炼钢的造渣。它又是制造氢氟酸和其它各种氟化物的基本原料、玻璃制造工业上制造隔音和光学玻璃及制造焊药的原料之一。因此快速、准确地测定萤石中主成分氟化钙含量对指导生产有着广泛的意义。萤石的经典分析方法是将碳酸钙和氟化钙分离后 ,再分别测定。这种方法准确度高 ,但分析周期较长 ,较难适应生产日益发展的需要。本法采用样品以Ｈ3 ＢＯ3 ＨＣｌ混合加热溶解 ,氟化钙转入溶液中 ,此时硼与氟结合成络离子。2ＣａＦ2 +4ＨＣｌ+Ｈ3 ＢＯ3 2ＣａＣｌ2 +ＨＢＦ4 +3Ｈ2 Ｏ继续蒸发溶液时 ,…     

沉淀分离滴定法测碳酸钡含量

碳酸钡是一种重要的无机化合物 ,适用于陶瓷、光学玻璃、颜料、油漆等工业 ,测定方法通常采用称重法 ,但其时间长 ,需要恒重等手续。本文采用滴定法 ,节省了时间 ,并对其精密度及准确度进行了考察 ,结果较好。1　原理在近中性乙酸铵介质中 ,以过量的重铬酸钾沉淀Ｂａ2 +,过量的重铬酸钾以硫代硫酸钠返滴 ,从而求出碳酸钡的含量。主要反应式如下 :ＢａＣＯ3+ 2ＨＣｌＢａＣｌ2 +Ｈ2 Ｏ +ＣＯ2 ↑2Ｂａ2 ++Ｃｒ2 Ｏ2 - 7+Ｈ2 Ｏ 2ＢａＣｒＯ4 ↓ + 2Ｈ+Ｋ2 Ｃｒ2 Ｏ7+ 6ＫＩ + 14ＨＣｌ 3Ｉ2 + 2ＣｒＣｌ3+　　 7Ｈ2 Ｏ + 8ＫＣｌ2Ｎａ2 Ｓ2 …     

四元交互体系Li~+,K~+/Cl~-,CO_3~(2-)-H_2O在298K时相平衡及物理化学性质研究

位于我国西藏腹地的扎布耶盐湖 ,是世界上罕见的富含锂、钾等碱金属和富含硼的碳酸盐 硼酸盐的特种盐湖 .该湖卤水主要由Ｌｉ+,Ｎａ+,Ｋ+,Ｃｌ- ,ＣＯ2 -3 ,ＳＯ2 -4 ,Ｂ4Ｏ2 -7,ＨＣＯ-3 等物种构成 .显然 ,开展该湖卤水体系的理论和实验相平衡研究 ,不仅对该种类型盐湖卤水的成因和成矿规律、对于这类复杂水盐体系化学行为的理论和实验描述研究具有重要意义 ,而且对于该盐湖卤水盐类资源综合利用方案的制定具有指导意义 .但是 ,迄今为止 ,除陈郁华[1 ] 报道过关于 2 98Ｋ条件下该湖卤水体系等温蒸发实验研究的结果外 ,尚未见到关于该湖卤…     

铜对Mn/Al_2O_3氨还原SO_2到单质硫催化性能的影响

ＳＯ2 是危害最为严重的大气污染物之一 ,也是造成酸雨的元凶。将ＳＯ2 选择性还原为单质硫 ,既能消除ＳＯ2 对环境的污染 ,又能回收单质硫 ,具有特别重要的意义。根据所用的还原剂的不同 ,催化还原ＳＯ2 到单质硫可分为Ｈ2 、炭、烃类 (主要是ＣＨ4 )、ＣＯ和ＮＨ3还原法[1] 。氨还原法是基于氨的催化分解生成Ｎ2 和Ｈ2 混合气 ,其中的Ｈ2 再还原ＳＯ2 到硫和Ｈ2 Ｓ ,然后进行高温Ｃｌａｕｓ反应生成单质硫。Ｐａｉｋ[2 ] 等以第四周期过渡金属硫化物载于Ａｌ2 Ｏ3 作为催化剂 ,研究了Ｈ2 还原ＳＯ2 为单质硫的反应 ,认为过渡金属硫化物是…     

羟基磷灰石合成工艺研究

羟基磷灰石 [Ｃａ10 (ＰＯ4 ) 6(ＯＨ) 2 ,简称ＨＡＰ]是80年代发展起来的新型牙科、骨科材料 ,其成份接近生物体骨质的无机成份 ,能诱发新骨生长 ,具有良好的生物相容性。ＨＡＰ的制备方法较多 ,有溶胶 凝胶法[1,2 ] 、沉淀法、电化学合成法[3 ,4 ] 等。1　实验1 1　试剂与仪器所用试剂除磷酸三丁酯为化学纯外 ,其它都是分析纯。美国尼高力公司 (ＮＩＣＯＬＥＴ)傅里叶变换红外光谱仪 (ＭＡＧＮＡ 5 5 0 (Ⅱ ) )。1 2　ＨＡＰ的制备1 2 1　溶胶 凝胶法合成ＨＡＰ　我们以不同原料制备了ＨＡＰ。第一种方法是以Ｃａ(ＮＯ3)2 与磷酸三丁…     

常压气相氧化羰基化合成碳酸二乙酯

碳酸二乙酯是一种重要的有机化工原料,可广泛用于合成农药如脱叶灵,医药如喹啉酮衍生物,中间体3-氧硫代羧酸酯,还可用于电子管阴极的镀层[1-3]。生产碳酸二乙酯的传统方法为:无水乙醇与光气反应生成氯甲酸乙酯,氯甲酸乙酯继续与乙醇反应生成碳酸二乙酯后经水洗蒸馏制成。使用光气为原料对设备的要求较高。我们在常压下气相羰基化合成碳酸二乙酯[4]:2ＮＯ+Ｃ2Ｈ5ＯＨ+0.5Ｏ2→2Ｃ2Ｈ5ＯＮＯ+Ｈ2Ｏ(1)ＣＯ+2Ｃ2Ｈ5ＯＮＯ→(Ｃ2Ｈ5Ｏ)2ＣＯ+2ＮＯ(2)产生的一氧化氮可与氧气和乙醇进行反应再生为亚硝酸乙酯,符合原子经济反应且几乎不放出对…     

Mg~(2+),Li~+//SO_4~(2-)-C_2H_5OH-H_2O体系在25℃的等温互溶度和相关系

某些有机溶剂加入无机水盐体系能较大地改变无机盐在水溶液中的溶解度 ,反之 ,某些盐类也可显著地影响双液系组分之间的相对挥发度 ,这方面的理论研究和应用研究已有较多报道[1 ,2 ] 。利用一些有机溶剂的强盐析作用 ,以期实现对某些混合盐类的分离和纯化 ,在盐卤工业等领域具有很重要的意义。Ｎｉｋｏｌｓｋａｙａ等[3] 和潘焕泉等[4] 分别测定了三元系Ｌｉ2 ＳＯ4 Ｃ2 Ｈ5ＯＨ Ｈ2 Ｏ在不同温度 (- 2 0～ 5 0℃ )下的互溶度 ,没有发现该体系产生分层现象 ,确定了各温度下的平衡固相皆为Ｌｉ2 ＳＯ4·Ｈ2 Ｏ。Ａｒａｖａｍｕ ｄａｎ[5] 及…     

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.