烟酸敏感场效应传感器的研制及应用

烟酸是吡啶-3-羧酸,具有B族维生素的活性,用于预防和治疗癞皮病,减低由于磺胺类、砷剂、麻醉药等所引起的中毒现象,一般常用中和滴定法、紫外分光光度法测定其含量。关于液膜烟酸电极和PVC膜烟酸电极的研制及应用已有报道,我们采用三辛基甲基烟酸铵缔合物为活性物,与新型离子选择性场效应传感器结合,制成了烟酸敏感场效应传     

铜与缓冲剂Bicine及芳香氮碱三元混配配合物的稳定性研究

用pH电位滴定法测定了HL的酸常数（L＝苯并咪唑，吡啶，3，4－二甲基吡啶，异喹啉）以及二元配合物CuL2＋和三元混配配合物Cu（Bic）L＋（Bic-＝Bicine的单电荷阴离子）的稳定常数．三元混配配合物相对于二元配合物的稳定性用△lgKCu＝lgKCu(Bic)Cu(Bic)L-lgKCuCuL来表示．结果表明由于δ-π协同效应和疏水作用，三元混配配合物有较强的稳定性     

CPC零电流示波电位滴定法测定陶瓷铂金水中的铂（Ⅳ）

提出了一个快速测定铂（Ⅳ）的零电流示波电位滴定法。以氯化十六烷基吡啶为滴定剂，用铂电极和银电极为指示电极，利用阴极射线示波器荧光屏上荧光点的突然位移来指示ＣＰＣ滴定ｐｔ（Ⅵ）的终点，具有灵敏、准确、快速等特点。用该法测定陶瓷铂金水中的铂，结果良好。     

浊度滴定法

报道了一种实用的浊度传感器及浊度滴定仪，以及一种利用此仪器检测溶液的浑浊程度（溶液中散射光相对强度）来判断沉淀反应滴定终点的方法。将一束光线通入溶液，在溶液中与其垂直的方向上，利用内置浊度传感器检测散射光相对强度；随着滴定剂的加入，溶液将渐变得浑浊，散射光相对强度逐渐增强。如果沉淀反应完全且溶解度足够小，散射光相对强度将在化学计量点处达最大值，由此可判断滴定终点。以AgNO3溶液滴定NaCl溶液为例俊证了浊度滴定法，结果表明：浊度滴定法样化学指示剂法适用于更低的浓度；在适当的条件下浊度滴定法的精密度和准确度均可＜0.2%。     

脂肪醇聚氧乙烯醚羟值的检测方法的改进

以4-二甲氨基吡啶为催化剂,过量乙酸酐为乙酰化试剂,吡啶为溶剂,用电位滴定法快速测定脂肪醇聚氧乙烯醚(AEO)的羟值,并对催化剂、反应条件、系统的适应性进行了探讨。用该方法对5种不同羟值的AEO样品进行了测定,测定结果的相对标准偏差0.5%(n=6),且测定结果与国标法测定结果的相对误差在±1%之内。     

氧化氩氮-乙炔火焰原子吸收光谱法测定钛铝钒合金中铝

铝常用的测定方法有碱分离-EDTA络合滴定法、氟化钠分离-EDTA容量法、络天青S光度法、铜铁试剂分离-络天青S光度法、络天青S-氯化十六烷基吡啶光度法、偶氮氯膦Ⅰ光度法、苯甲酸铵分离-EDTA络合滴定法、氢氧化钠分离-六氟铝钾沉淀酸碱滴定法、原子吸收光谱法等。铝作为强抗氧化剂加入到钛铝钒合金中，具有细化晶粒、改善抗氧化和耐腐蚀性能的作用，但多了会对性能造成不良影响。因此必须对原材料中铝的量严格控制。化学法测定钛铝钒合金中铝含量，缺点是使用的试剂种类多，而且方法比较复杂繁琐，不便于掌握。用火焰原子吸收光谱法测定钛铝钒合金中铝，方法简单、快速、易于掌握、同时测定、精确度高，能满足原材料复检过程中分析的需要。     

脂肪醇聚醚产品及脂肪醇羟值的快速测定

以4-二甲氨基吡啶为催化剂,过量乙酸酐为乙酰化试剂,吡啶为溶剂,用电位滴定法快速测定脂肪醇聚醚产品及脂肪醇羟值,并对催化剂、反应条件、系统的适应性进行了探讨。用该方法对5种不同羟值的脂肪醇聚醚及脂肪醇样品进行了测定,测定结果的相对标准偏差小于0.5%(n=6),且测定结果与国标法测定结果相符合,相对误差在±1%之内。     

PVC膜修饰电极上零电流示波电位滴定法测定硼的研究

以氯化十六烷基吡啶（ＣＰＣ）和氟硼酸钠形成的离子缔合物为活性物质，制成ＰＶＣ膜涂层石墨电极，提出了一个快速测定硼的零电流示波电位滴定法。以ＣＰＣ为滴定剂，用ＰＶＣ膜电极为指示电极，甘汞电极为参比电极，利用阴极射线示波器荧光屏上荧光点的突然位移来指示ＣＰＣ滴定硼的终点，具有灵敏、准确、快速等特点，用该法测定玻璃中的硼，结果良好。     

纤维素在离子液体中的均相乙酰化及其选择性

在1-烯丙基-3-甲基咪唑氯盐(AMIMCl)离子液体中进行了纤维素的均相乙酰化. 酯化剂为乙酸酐和乙酰氯以及加入或不加入催化剂吡啶. 用滴定法确定了产物的取代度(DS), 根据13C NMR考察了产物的取代度分布. 结果表明: 酰氯酰化的反应速度比酸酐快; 吡啶能加快乙酸酐的酯化反应, 但减慢酰氯的反应; 使用乙酸酐/吡啶酯化时所得产物具有特殊的取代度分布, 即DSC-2>> DS C-3.     

表面活性剂存在下有机弱酸的自动电位滴定法

有机弱酸普遍存在于医药、农药及食品中，它们的测定方法研究，对生产质量控制、食品安全和环境保护有重要意义。目前，有机弱酸的测定方法主要有固定pH法、双点电位滴定法、单点pH滴定法、线性电位滴定法、直接电位滴定法、非水滴定法、远红外光谱滴定法等，这些方法各有特点，但难尽人意。如多数有机弱酸的水溶性较差，必须在非水介质中进行，增大了测定难度和测量成本。     

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.     

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.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.