交换稀土La^3^＋离子NaY型分子筛的交流电导

本文用Ｘ－射线衍射，原子吸收光谱，差热热重，化学分析等方法测定了交换Ｌａ＾３＾＋离子ＮａＹ分子筛的物相及组成，用交流阻抗谱仪测量了其离子电导。由电导率随温度的变化，得到ＮａＹ和ＬａＮａＹ的电导表观活化能为４９．６ＫＪ／ｍｏｌ和４１．３ＫＪ／ｍｏｌ。讨论了交换Ｌａ＾３＾＋离子对分子筛骨架结构中的钠离子分布，落位及其扩散迁移的影响。     

3－乙酰乙酰基－4－羟基香豆素希土配合物的合成和性质

本文报道了稀土与３－乙酰乙酰基－４－羟基香豆素配合物的合成，其化学组成为Ｌｎ（Ｈａａｃ）３．ｎＨ２Ｏ（Ｌｎ为Ｌａ，Ｐｒ，Ｎｄ，Ｇｄ，Ｄｙ，Ｅｒ，ｎ为１或２），基于Ｈ－ＮＭＲ，ＩＲ的结果，提出了稀土离子与配位体４位羟基氧与邻近羰基双齿配位结构，对Ｎｄ＾３＋及Ｅｒ＾３＋配合物的超灵敏吸收带的形状和吸收强度等也作了讨论。     

超微NaY分子筛的合成（II）—添加铝络合剂的影响

NaY分子筛合成体系中添加铝的络合剂（乙二胺四乙酸、柠檬本矣醋酸）,可有效地减小分子筛的晶粒尺寸及增加分子筛的晶化速度和SiO2/Al2O3物质的量比,在添加柠檬酸的合成体系中,考察了柠檬酸的添加量对NaY分子的筛晶化的影响,发现存在着一个最佳的柠檬酸的添加量范围,即n（柠檬酸）：n（氧化铝）≤2：1,在此范围内,NaY的晶化速率和硅铝比较高,而晶粒尺寸较小。     

氨三乙酸稀土络合物配体交换反应的NMR研究

利用变温＾１３Ｃ，＾１Ｈ－ＮＭＲ研究了过量配体存在下，氨三乙酸稀土络合物Ｌｎ（ＮＴＡ）２（Ｌｎ＝Ｃｅ，Ｐｒ和Ｎｄ）配体交换反应。在中必不溶液中，分子间的配体交换过程按中下机制进行：Ｌｎ（ＮＴＡ）２＾３－＋ＨＮＴＡ＾２－＝Ｌｎ（ＮＴＡ）（ＮＴＡ）＾３＋＋ＮＨＴＡ＾２－由溶液中溶液中自由ＮＴＡ信号线宽分析了交换速率、确定了反应的活化能。结果表明，分子间配体交换反应化能与相应稀土络合物热力学稳定性有一定     

超微NaY分子筛的合成(Ⅱ)——添加铝络合剂的影响

NaY分子筛合成体系中添加铝的络合剂(乙二胺四乙酸、柠檬酸和醋酸),可有效地减小分子筛的晶粒尺寸及增加分子筛的晶化速度和SiO2/Al2Oa物质的量比.在添加柠檬酸的合成体系中,考察了柠檬酸的添加量对NaY分子筛晶化行为的影响.发现存在着一个最佳的柠檬酸的添加量范围,即n(柠檬酸)：n(氧化铝)≤2：1,在此范围内,NaY的晶化速率和硅铝比较高,而晶粒尺寸较小.     

微波诱导快速合成纳米NaY分子筛

报导了一种在常压回流微波加热条件下,可使合成的NaY分子筛晶粒尺寸减小至100 nm以下的方法.添加柠檬酸的晶化速率接近添加稀土离子的晶化速率,合成60 min后两者得到的NaY分子筛的晶粒度和硅铝比接近,约为40 nm和5.2,晶粒度小且硅铝比高于在相同条件下没有添加合成得到的NaY分子筛.微波合成的NaY分子筛的晶粒度明显小于常规相同配比所得样品的晶粒度且晶化时间明显缩短,充分证明了微波加热快速均匀且能够得到较小晶粒度的特点.     

稀土对盐浴渗钒动力学的影响

在盐浴渗钒中添加稀土对表面渗钒有明显的催渗作用,渗钒速度约提高３０％－４０％,。对９５０℃经不同时间渗钒的试样测定渗层度（ｘ）。将ｘ及所对应时间（ｔ）代入经验公式ｘ＾ｎ＝Ｋｔ（ｌｎｘ＝ｌｎＫ／ｎ＋ｌｎｔ／ｎ）,经一元线性回归处理可知,ｘ与ｔ之间满足ｘ＾２＝Ｋｔ抛物线关系,添加稀土可以加快渗剂反应而增大渗剂钒势。稀土的强还原性使钢件表面的氧化还原而活性其表面,稀土渗入钢基体和ＶＣ渗层,会增大晶体缺陷密度,使碳原子扩散易于进行,稀土的添加可降低碳原子扩散激活能,起到催渗的效果。     

非水溶剂中稀土离子和穴醚（2.2）配合物的电导研究

用电导法研究了２５℃时，硝酸稀土和穴醚在不同溶剂中的配位行为。计算了１：１配合物的稳定常数及摩尔电导率，在非水溶剂（ＣＨ３）２ＣＯ．ＣＨ３ＣＮ．ＣＨ３ＯＨ和ＤＭＦ中，由于配位过程中伴随着Ｌｎ离子的溶剂化作用，稀土和穴醚配合的稳定常数随Ｌｎ原子序数的增加而变化不大。     

小颗粒NaY分子筛透明液相导向剂的制备及其性能

小颗粒ＮａＹ分子筛透明液相导向剂的制备及其性能马跃龙，陈诵英，彭少逸（中国科学院山西煤炭化学研究所煤转化国家重点实验室，太原０３０００１）关键词ＮａＹ分子筛，制备，常规导向剂，透明液相导向剂，使用寿命，老化时间ＮａＹ分子筛作为催化剂组成部分广泛应用于...     

几种稀土卟啉配合物的固相合成及电化学性质研究

在固相条件下合成了４种四（对甲氧基苯基）卟啉稀土（Ｌｎ＝Ｌａ＾３＋,Ｐｒ＾３＋,Ｎｄ＾３＋,Ｄｙ＾３＋）配合物。用元素分析、ＩＣＰ、ＵＶ及ＩＲ光谱进行表征,用循环伏安法研究了它们的电化学性能,实验结果表明,它们的电化学性质相似。在循环伏安图中出现了三对氧化还原峰。第一对为「Ｃ４８Ｈ３６Ｎ４Ｏ４Ｌｎ（Ⅲ）」＾＋／「Ｃ４８Ｈ３６Ｎ４ＯＬｎ（Ⅱ）」,第二为「Ｃ４８Ｈ３６Ｎ４Ｏ４Ｌｎ（Ⅱ）」／「Ｃ４８Ｈ３６Ｎ４Ｏ４Ｌｎ（Ⅰ）」＾－１,第三对为「Ｃ４８Ｈ３６Ｎ４ＯＬｎ（Ⅰ）」＾－／「Ｃ４８Ｈ３６Ｎ４ＯＬｎ」＾２－。     

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.     

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.     

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.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

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.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.