海藻酸钠溶液溶胶—凝胶相转移的温度效应及IR光谱研究

考察了３ｗｔ％海藻酸钠溶液中加入Ｃｕ＾２＾＋，Ｃ０＾２＾＋后，体系的粘度，电导与离子浓度，温度的关系，结合ＩＲ光谱对海藻酸钠溶液在溶胶－凝胶相转移过程中的分子结构与构型变化进行了解剖。     

钇在二甲基亚砜溶剂中的电化学行为

研究了ＹＣｌ３－ＬｉＣｌＯ４－ＤＭＳＯ（二甲基亚砜）体系电导率与温度的关系,及钇在Ｐｔ和Ｃｕ电极上的电化学行为。结果表明,Ｙ＾３＋在Ｐｔ和Ｃｕ电极上可一步不可逆还原为Ｙ,在铜电极上于－２．５００Ｖ（ｖｓ ＳＣＥ下恒电位电解,可获得粘附性好、Ｙ含量达９７．９％（质量分数）的均匀沉积膜。利用循环伏安法、计时电流法、计时电位法测定了Ｙ＾３＋离子在２９８Ｋ下,ＹＣｌ３－ＬｉＣｌＯ４－ＤＭＳＯ溶液中的扩散系     

微晶萘固相萃取分离富集及ICP—AES测定Cu,Mn的研究

报道以微晶萘作吸附载体的固相萃取分离及ＩＣＰ－ＡＥＳ测定Ｃｕ，Ｍｎ的新方法，详细研究了溶液酸度，试剂浓度，萘用量及共存离子对待测物回收率的影响，考查了加入适量的Ｃｏ＾２＋，对富集痕量Ｃｕ＾２＋Ｍｎ＾２＋辅助作用，本法用于生物样品马尾藻及小牛肝中Ｃｕ，Ｍｎ的测定，分析结果与标准值吻合。     

流动载体对以二—（2—乙基己基）磺化琥珀酸钠为表面活性剂的W／O型微 …

研究了一些流动载体对以二－（２－乙基己基）磺化琥珀酸钠（ＡＯＴ）为表面活性剂，正庚烷为油性溶剂Ｗ／Ｏ型微乳状液在迁移痕量金属离子Ｃｕ＾２＋的影响，实验结果表明，１－（２－吡啶偶氮）－２－萘酚（ＰＡＮ）能大大促进Ｃｕ＾２＋的迁移，使其迁移率从７０％上升到１００％，用高盐度溶液对微乳进行了破乳，得到Ｃｕ＾２＋的富集倍数为６，回收率约为１００％。     

倒数示波计时电位法在合金样品测定中的应用

应用倒数示波计时电位法，在含有吸附络合物的溶液中，采用桂汞电极作为极化电极，测定了Ｃｕ＾２＋、Ｎｉ＾２＋、Ｃｄ＾２＋、Ｐｂ＾２＋等几种金属离子的检测下限，并通过沿（ｄＥ／ｄｔ）－１￣Ｅ曲线上的峰高对合金样品进行定量分析，得到满意结果。实现了示波分析由常量到微量的飞跃。     

Na型斜发沸石上Na+-Cu2+离子交换过程动力学

用静态离子交换法研究了Ｎａ型斜发沸石上２Ｎａ＝Ｃｕ＾２＋离子交换动力学，分别测定了液膜扩散常数Ｒ，粒内扩散系数Ｄ和滞留时间Ｔｄ，实验发现，离子交换起始为液膜扩散控制，随后在交换的大部分时间内为粒内扩散控制，并就温度、浓度对离子交换过程速率，Ｃｕ＾２＋平衡交换数量以及滞留时间的影响进行了讨论。     

褐藻酸钠对Cu2+、Pb2+交换与吸附性能的研究

本文研究了褐藻酸钠与Ｃｕ＾２＋,Ｐｂ＾２＋交换行为,通过海藻酸钠溶液与Ｃｕ＾２＋,Ｐｂ＾２＋的絮凝,测得两种离子最大交换量。考察了褐藻酸钠固体粉末与Ｃｕ＾２＋,Ｐｂ＾２＋在不同的反应条件下的离子交换与吸附行为。实验表明ｐＨ值,温度,时间,配比等条件是影响交换与吸附的因素,其吸附行为在一定的温度和一定的浓度范围内能较好的符合Ｆｒｅｕｎｄｌｉｃｈ等温吸附式。     

低温凝固高氯酸水溶液体系中固体汞电极性能和铜的氧化还原行为研究

本文介绍凝固电解质体系中固体汞电极的使用特性。在凝固的ＨＣｌＯ４水溶液中，固态汞电极上发生的电化学反应与液态汞和溶液体系中的非常相似。本实验测定了温度降低对Ｃｕ＾２＋的氧化还原过程的影响。最低实验温度达到－１００℃。介质体系的结构变化对于Ｃｕ＾２＋的还原反应和金属互化物有重大影响。     

铜的腺嘌呤络合物在悬汞电极表面上的吸附形态和氧化还原行为

本文详细地研究了铜的腺嘌呤（Ａｄｅ）络合物在悬汞电极（ＨＭＤＥ）表面上的吸附形态和伏安行为。实验结果揭示了单层吸附饱和之前有Ｃｕ＾＋Ａｄｅ，Ｃｕ２＾＋（Ａｄｅ）２形态的共吸附作用，随着电极表面的吸附浓度增长，Ａｄｅ络合物分子有从平面向垂直吸附的定向作用。哦的多层吸附和聚合作用发生在吸附分子垂直定向以后。本文还测定了有关电极过程的动力学参数。     

铂电极对铜和银非电对离子瞬时响应信号的研究

用活度阶梯变化法测量了铂电极对Ｃｕ＾２＋、Ａｇ＾＋的瞬时响应信号为单峰类型，并且在一定浓度范围呈Ｎｅｒｎｓｔ关系。进一步证实了平衡时间子交换产物的摩尔分数Ｓｅｑ值对瞬时响应信号类型的影响。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.