酸碱平衡计算软件CurTiPot在大学化学教学中的应用

介绍了酸碱平衡计算软件CurTiPot的基本功能与特点。结合大学化学在酸碱质子理论以及在此基础上延伸的教学内容,分别介绍了缓冲溶液pH的计算、酸碱滴定过程的模拟以及水中物质随pH的形态分布的计算功能的使用方法与应用实例。该软件在大学化学的课堂教学中有助于学生了解溶液各项参数对溶液pH、滴定过程及物质形态分布等的影响,提升教学质量。此外该软件也可在科研工作中替代繁杂的人工计算,提高工作效率。     

信息与服务

可编程序计算器在分析化学中的应用使用CASIO fx-3600 p可编程序计算器,对分析数据进行程序运算,就下述问题可达到与微机相近的效果。“pH计算程序”可计算弱酸溶液、弱碱溶液、弱     

基于p值流程图计算水溶液酸碱度的方法

介绍一种用于酸碱度计算的p值流程图,学生通过回答流程图上的一系列问题,并找到正确的方程式,即可方便地求解常见溶液pH的计算问题,而不需要借助计算器。     

二甲酚橙指示EDTA测锌的酸度控制讨论

对二甲酚橙为指示剂,EDTA滴定Zn的酸度问题进行了讨论.计算得出测定的最佳酸度范围在pH5.1 ～6.0之间;同样经计算,表明（1＋1） HCl的加入体积在3～ 6mL之间可控制溶液pH在5.5 ～6.0之间.     

酸碱滴定终点误差的快速估算法——基于CurTiPot酸碱滴定曲线的快速绘制

利用CurTiPot软件快速绘制酸碱滴定曲线,并在相对误差概念的基础上,实现了酸碱滴定终点误差的快速计算。     

一种处理酸碱平衡体系的新方法

在化学教学和研究工作中,经常要研究酸碱溶液体系的平衡情况,其中最重要的问题是溶液的酸度,因为知道了溶液的酸度,就可以算得溶液中所有平衡物种的浓度。在分析化学教科书中对各类酸碱溶液pH的计算讨论很多,但至今还没有归纳出一个适用     

共价键合修饰壳聚糖pH传感器的研制

以共价键合的方法将壳聚糖修饰到玻碳电极上制成了pH传感器,探讨了该传感器的性能及作用机理.结果表明该传感器在pH 0.7～11.0的范围内电极电势与pH符合Nernst响应,斜率为58.3 mV/pH,可准确测定较高酸度溶液的pH,克服了玻璃pH传感器的"酸误差"的缺点.该传感器内阻小,易微型化,在一定的pH范围内对温度不敏感且具有较好的准确度和重现性,较快的响应速度.可用于雨水和饮料等实际样品溶液的pH的测定.     

配位滴定法测定锌含量的合适酸度条件

调节待测体系的pH值是配位滴定中一种重要的选择性滴定手段。采用CTE1.0程序计算了不同酸度条件下的终点误差,同时用配位滴定法测定了模拟样品和市售药品中的锌含量。计算结果和实测结果均表明,在不含钙离子的待测体系中,测定锌离子含量的合适酸度条件为pH=6;在钙、锌混合离子溶液中,测定锌含量的合适酸度条件为pH=5。平行测定实验的相对标准误差为1.63%,加标回收率为99.1%-101.8%。     

络合滴定中由副反应系数Igα_(L(H))计算pH的新方法

本文根据溶液中酸碱组分的对数浓度与pH的关系,提出了由副反应系数计算溶液pH值的新方法。它使一个一元高次方程的求解简化为加减运算,为确定络合滴定的适宜酸度提供了一个简便的方法。     

关于碘量法滴定铜的几个问题——答读者问

碘量法测定铜的应用迄今已有百余年历史。对其测定条件及干扰的消除方法不断有所改进。在条件掌握合适的情况下可获得较准确的结果。该方法的基本反应为Cu(Ⅱ)与碘离子定量反应生成碘化亚铜和游离碘。随即用硫代硫酸钠标准溶液滴定所释的碘,从而间接计算试样中铜的含量。分析操作中的关键是: 1 酸度的控制 要求控制溶液的酸度在pH 3.4～4.0之间。如pH〈3,则砷、锑将参与反应,而且空气的氧化作用使终点反复。如pH〉4,则可能产生铜的氢氧化物沉淀,导致结果偏低。通常用乙酸-乙酸盐缓冲体系控制酸度。也可用NH_4HF_2作为缓冲剂。氟化氢铵还可掩蔽Fe(Ⅲ)而避免其干扰。为避免大量氟化物对环境的污染,也可采用其它铁的掩蔽剂,如三聚磷酸钠等。     

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%).     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.