对“红光照射硫酸铜溶液和氢氧化铁胶体实验”的探究

用激光笔发出的红光照射氢氧化铁胶体,有丁达尔效应;而用红光照射硫酸铜溶液,则无丁达尔效应,于是得出结论:可用有无丁达尔效应来鉴别胶体和溶液。但大家可能都忽视了物理学上的一个问题,那就是“蓝色是可以吸收红色光的”,所以CuSO4溶液肯定是没有丁达尔效应的。就“CuSO4溶液没有丁达尔效应”这一问题,笔者引导学生进行实验探究,最终解决问题。     

利用SPSS17.0探讨制备氢氧化铁胶体的最佳实验条件

氢氧化铁胶体性质实验是高中化学中的一个重要实验,若制备胶体实验操作不当,很难得到丁达尔现象明显且稳定性良好的胶体。通过实验方案的改进与设计,用一定浓度的氢氧化钠溶液和氯化铁溶液直接混合制取氢氧化铁胶体,并测定其pH。利用SPSS17.0软件进行正交实验设计,探讨氢氧化铁胶体制备的影响因素、显著性水平及最佳实验条件。     

利用数字化实验探究氢氧化铁胶体粒子的形成过程

利用数字化实验对氢氧化钠溶液和氯化铁溶液反应制备氢氧化铁胶体过程中电导率和浑浊度的变化进行探究，得到电导率和浑浊度随氢氧化钠溶液滴加的变化规律。通过宏观、微观、符号和曲线四重表征深入分析，阐明了胶体、溶液和浊液的本质区别是分散质粒子直径的不断增大，从而帮助学生从微观上理解不同分散系的本质区别。     

制备硅酸胶然适宜条件的探讨

全日制十年制学校高中课本第一册,学生实验九中,硅酸胶体制备方法是:“在一个试管里加入5至10毫升1M盐酸,并加入1毫升水玻璃,然后用力振荡,即得硅酸溶胶。”由于课文只指出使用韵盐酸浓度(1M),未说明水玻璃浓度,也未指明两份溶液的准确体积比,按此法进行实验,有时1分钟即形成胶冻,有时所制得的混和液要经过24小时后方能产生丁达尔效应。怎样才能做好制备硅酸胶体的实验呢?实验的适宜条件是什么?下面就这一问题作些探讨。     

黄豆蛋白胶体的制备和聚沉

物理化学中胶体化学部分原有实验是氢氧化铁胶体制备和电泳速率测定,属于验证性实验,对胶体特征的表征局限于电学性质,缺少对粒径、光学性质的表征探究及创新训练。本文通过黄豆蛋白胶体的制备、表征和聚沉,将原先的验证性实验改进为具有综合性和探究性的实验。通过物理分散法获得黄豆蛋白胶体,对其粒径、光学性质、电学性质进行了表征,并对聚沉条件进行探究,最终获得豆腐产品。结果表明,黄豆蛋白胶体粒径范围为20–120 nm、最可几分布为51 nm,胶粒平均带电-41.8 mV。通过丁达尔效应,在与入射光垂直方向观察到散射的蓝光,并观察到透过的光呈橙红色。通过探究反离子种类、温度、pH等条件的影响,加深了对植物蛋白胶体聚沉过程的理解。该实验引入了现代Zeta电位及粒度分析仪,加入了蛋白质聚沉的特殊情况,强化对书本知识的延伸应用。产品豆腐与生活密切联系,有利于思政教育,彰显化学魅力。     

纳米玉米醇溶蛋白微球稳定的O/W型Pickering乳液

利用相分离工艺制备玉米醇溶蛋白(zein)纳米微球,微球粒径可控制在40 nm左右;经旋转蒸发制得zein溶胶体系,zein溶胶具有明显的丁达尔现象,静置数月不聚沉,Zeta电位法测得zein微球在pH值为4.0时分散性能最佳。 以纳米zein微球为固相稳定剂制备O/W型Pickering乳液,考察了zein胶体加入量、油水体积比等因素对乳液稳定性的影响。 实验结果表明,zein胶体加入量的质量分数控制为0.4%,高油水体积比将有利于Pickering乳液的长时间稳定。 基于zein分子的两亲结构和界面组装特点,提出了zein微球稳定Pickering乳液的作用机制。     

《新编胶体与界面化学》

刘洪国、孙德军、郝京诚编著本书以界面为主线,介绍了与气/液、液/液、气/固和液/固界面相关的基本原理和基础知识,并穿插介绍了与这些界面相关的部分分散体系,如泡沫、乳液、微乳液、溶胶等,并对表面活性分子在溶液中形成的胶束和囊泡分别进行了介绍。我们还特别针对近年来研究较为活跃的分散体系,如纳米乳液和Pickering乳液等的基本概念和进展做了介绍;并对胶体与界面化学的基本原理在纳米材料和超分子组装方面的应用做了阶段性综述。     

氢氧化铁胶体制备与性质实验的改进

针对现行的物理化学实验中的溶胶电泳实验,胶溶法存在容易失败的问题,水解法存在渗析纯化所需时间过长的问题,采用用盐酸溶液作为胶溶法的分散剂,对Fe(OH)3胶体实验进行了改进,省时简便,成功率高,可不经过渗析直接进行电泳实验。     

化学工业出版社化学专业图书推荐

正《新编胶体与界面化学》刘洪国、孙德军、郝京诚编著本书以界面为主线,介绍了与气/液、液/液、气/固和液/固界面相关的基本原理和基础知识,并穿插介绍了与这些界面相关的部分分散体系,如泡沫、乳液、微乳液、溶胶等,并对表面活性分子在溶液中形成的胶束和囊泡分别进行了介绍。我们还特别针对近年来研究较为活跃的分散体系,如纳米乳液和Pickering乳液等     

演示丁达尔现象的好方法

教学中通常要观察丁达尔现象必须在暗室或有暗箱,因此一般条件下不能安排演示实验。自1982年以来,我在胶体教学中一直应用氦氖激光器作为光源,利用激光束的高亮度和不易发散的特点,在明亮的教室里成功演示了胶体的丁达尔现象,实验效果非常好,即使在有阳光的屋子里,坐在教室后排的学生也能清楚地看到实验现象:在胶体溶液里有一条“光路”出现,而蒸馏水或真溶液没有光路。我将此法用于学生实验课更显得十分方便。     

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.