阳离子表面活性剂混合胶团对2,4-二硝基氯苯水解反应的 催化作用

研究了阳离子表面活性剂混合胶团对2,4-二硝基氯苯(DNCB)碱性水解反应的催化作用。结果表明：(1)在十六烷基三甲基溴化铵(CTAB)和十六烷基溴化吡啶(CPB)混合溶液中DNCB水解一级速率常数k1与混合胶团中CTAB或CPB的摩尔分数有直线关系,表面活性剂形成理想的混合胶团。(2)辛基三甲基省化铵(OTAB)与CTAB,CPB的cmc值相差很大,在它们的混合胶团中OTAB含量极少,DNCB水解k1与CPB/OTAB混合胶团中CPB摩尔分数的关系与直线呈负偏差。(3)在CTAB(或CPB)与OTAB混合体系中OTAB起溴盐作用,使催化活性降低。用假相离子交换(PIE)模型对所得结果给出了定量的处理和解释。     

咪唑啉型表面活性剂组成微乳液的热力学性质

由咪唑啉型表面活性剂、醇、水和正十六烷组成微乳液，探讨了该微乳液中醇从油相转移到界面相时的自由能变化及温度对自由能变化的影响，算得了熵变和焓变。     

易水解类表面活性剂的表面与胶团性质

对直链烷基羧酸盐与烷基氯化伯铵两类易水解型表面活性剂进行了较系统的研究,发现pH 值、温度、 盐浓度的变化对体系表面性质及胶团形成有较明显的影响.二类体系中相应水解产物的存在均可较大幅度地提高体系的表面活性,但pH 值在碱性范围内的变化仍对羧酸钠的表面性质与胶团形成有明显影响,而烷基氯化铵的表面性质与聚集能力在酸性条件下则主要受盐浓度的影响,而不受pH 值影响.表明这两类易水解体系产生的极性有机物对各自体系的表面性质和聚集能力影响力度不同.考察了温度对易水解类表面活性剂的影响,并利用相分离模型对相应体系的胶团形成热力学参数进行了计算与讨论.     

季铵盐Gemini表面活性剂胶团水溶液的流变性质

用毛细管振荡剪切流动法研究联接基团为聚亚甲基链的季铵盐型Gemini表面活性剂C_12-s-C₁₂·2Br(s=2,4,8)的流变性质,并用动态光散射技术测定胶团生长过程中的胶团形状和大小的变化规律,探索联接基团长度对胶团形状、大小以及溶液流变性质的影响.实验结果表明,胶团形状和大小与联接基团长度有关,而溶液的流变性质主要由胶团的大小和形状所决定,球形和棒状(长椭球体)胶团溶液的流变性质以纯粘度为主,而线性胶团溶液则显示粘弹性质.此外,增加电解质浓度和降低温度均使溶液的粘度增大.     

三聚阳离子表面活性剂的合成

以甲胺盐酸盐和溴代烷为原料,通过季铵化反应合成了系列新型三聚阳离子表面活性剂12-n-12-n-12·3Br-(n=3,4,6),其结构经1H NMR,IR和元素分析表征.     

非离子型表面活性剂的微乳液热力学性质(Ⅱ)——醇类的原子数和活性剂的氧乙烯基团的影响

本文研究了由非离子型表面活性剂、水、甲苯和醇所组成的微乳液,发现醇的烃链上碳原子数直接与热力学函数成线性关系,氧乙烯基团数与自由能、焓以及熵的对数值亦成线性关系。这些结果对研究微乳液的构成和稳定性很有意义。     

高浓度区正负离子表面活性剂混合胶团的形状与大小变化

本文研究高浓度区正、负离子表面活性混合胶团的形态及大小随浓度的变化规律。根据正、负离子表面活性剂混合体系的相行为,胶团溶液的光散射以及流变性质测量,提出了混合胶团的棒-球转变模型。认为在较高浓度,随浓度增大,混合胶团经历了一个长棒变短,短棒变为球状的转变过程。     

氧杂氟表面活性剂及其与同电性碳氢表面活性剂混合溶液的表面吸附和胶团形成

研究了四种氧杂氟表面活性剂及其与同电性直链碳氢表面活性剂混合体系的表面活性;考察了混合体系中的表面吸附和胶团形成现象.在吸附层中分子间有明显的互疏作用,在溶液中倾向于各自形成胶团.还讨论了反离子结合度不同对理想混合胶团的组成及cmc的计算的影响,提出了一般的计算式.实验测得这些氧杂氟表面活性剂有较低的胶团反离子结合度.     

含偶氮苯基团的阳离子表面活性剂的合成

以对硝基苯酚为原料,经偶氮,Williamson醚化和季铵化反应合成了一种疏水基中间含偶氮苯基团的阳离子表面活性剂,其结构经1H NMR,IR和元素分析表征.     

Hydrolysis of 2,4-Dinitrochlorobenzene Catalyzed by Cationic Micelles

Micellar catalysis by nine cationic surfactants of the basic hydrolysis of 2,4-dinitrochlorobenzene(DNCB) was studied. The results obtained are as follows: (I) The second-order constants k₂ for the hydrolysis reaction of DNCB catalized by the cationic micelles increase by a factor of 11–100 than that in water. Plots of k₂ against the surfactant concentration show an S-type curve, and the catalytic effect is observed below the critical micelle concentration(CMC) of the surfactants. (2) For a series of surfactants, there is an optimal chain length for the alkyl of the surfactants to show the greatest catalytic effect. (3) The hydrolysis rate of DNCB decreases as the base concentration increases. (4) For the surfactants with the same hydrophilic and hydrophobic groups, chlorides have advantage over bromides in enhancing the reaction rate. These results can be interpreted in term of the changes in CMC, micelle size, solubilization capacity of the micelles, binding degree of counterion et al.     

1-(2-羟基-3,5-二硝基苯基)-3-[4-(苯基偶氮)苯基]-三氮烯-阴离子表面活性剂-季铵盐型阳离子表面活性剂显色反应及其应用

在三乙醇胺介质中,新试剂1-(2-羟基-3,5-二硝基苯基)-3-[4-(苯基偶氮)苯基]-三氮烯(HDNPAPT)与季铵盐型阳离子表面活性剂及阴离子表面活性剂(AS)反应显色,形成三元络合物.研究了显色体系的条件实验,建立了测定阴离子表面活性剂十二烷基苯磺酸钠(DBOSO_3Na)、十二烷基磺酸钠(DOSO_3Na)和十二烷基硫酸钠(DSO_4Na)的方法,表观摩尔吸光系数均达10~4以上.方法已应用于环境水样中阴离子表面活性剂的测定.     

多氯联苯醚的结构参数和热力学性质的密度泛函理论研究

采用密度泛函理论(DFT)方法在B3LYP/6-31G*水平上对209个多氯联苯醚(PCDEs)系列化合物进行了全优化和振动分析计算, 得到各分子的结构参数和热力学性质, 并研究了这些参数与氯原子的取代位置及取代数目(N_PCS)之间的关系. 结果表明: 分子平均极化率(α)、焓(H^Ө)、自由能(G^Ө)、恒容热容( )和熵(S^Ө)与N_PCS之间有很强的相关性(相关性系数r²分别为0.9955, 1.0000, 1.0000, 0.9918, 0.9995), 分子体积(V_m)和最高占据轨道能(E_HOMO)与N_PCS也有较好的相关性, 相关性系数r²分别为0.9735和0.9362. 设计等键反应, 计算了PCDEs系列化合物的标准生成热(Δ_fH^Ө)和标准生成自由能(Δ_fG^Ө). 根据异构体自由能的相对大小, 从理论上求得异构体的相对稳定性顺序.     

Role of Iron Carbonyls in the Inhibition of Oxygen Activation for the Oxidation of CO Catalyzed by Iron Oxide‐Supported Gold

Iron oxide‐supported gold samples were prepared by co‐precipitation from HAuCl₄ and Fe(NO₃)₃. The activities of the samples as CO oxidation catalysts were tested without thermal treatment and following treatments in flows of He and O₂ at various temperatures. It was found that the untreated samples and those treated in a flow of He at 150 °C were more active than samples that had been treated at 400 °C in either a flow of O₂ or of He. Infrared spectra recorded during CO oxidation catalysis indicate the presence of bonded CO molecules to cationic gold on all samples, whereas spectra of the least active catalysts indicate a predominant presence of Fe²⁺ carbonyls, which were highly stable under the conditions of our experiments. Our results indicate that in the least active samples the Fe²⁺‐bound CO blocks sites that would otherwise be available for oxygen activation.     

固载杂多酸催化合成2,4-二甲基-2-(4-甲基-3-戊烯基)-1,3-二氧五环

环缩酮类香料化合物[1 3]是在催化剂存在下由相应的酮和多元醇经缩合反应而制得。已报道的催化剂有质子酸[1]、固体酸[2,3]和某些金属盐类[4～7]等。本文以大孔阳离子交换树脂固载磷钨酸催化6 甲基 5 庚烯 2 酮与1,2 丙二醇的缩合反应,催化剂活性高,且可重复使用,后处理简便。1　实验1 1　仪器和试剂ＷＹＡ 1Ｓ阿贝折光仪;ＰＥ 2400ＣＨＮ元素分析仪;ＰＥ 783红外光谱仪。6 甲基 5 庚烯 2 酮、1,2 丙二醇、钨酸钠、磷酸氢二钠、盐酸等均为分析纯;大孔阳离子交换树脂(Ｄ001 ＣＣ型)。1 2　制备1 2 1　催化剂　以二水钨酸钠和十二水磷酸氢…     

2-[(4-氯苯基亚氨基)甲基]-8-羟基喹啉质子转移的理论研究

研究了2-[(4-氯苯基亚氨基)甲基]-8-羟基喹啉的三种质子转移途径: 分子内质子转移、水分子辅助质子转移和甲醇分子辅助质子转移. 以该席夫碱化合物的晶体结构作为模型, 在B3LYP/6-31＋G(d)水平上, 优化得到稳定态和过渡态的几何构型. 对三类质子转移前后的结构、能量、红外光谱、化学位移进行研究, 结果表明水分子辅助质子转移和甲醇分子辅助质子转移中, 水和甲醇分子利用氢键作用参与质子转移过程, 形成七元环状过渡态, 大大降低了反应的能垒, 有利于质子的转移, 氢键在降低活化能方面起着重要作用.     

Determination of Cationic Surfactant by Laser Thermal Lens Spectrometry

A novel method for the determination of cationic surfactant by laser thermal lens spectrometry was developcd,It was based on reaction between 1-hydroxy-2-(5-nitro-2-Pyri-dylazo)-8-aminonaphthaenc-3,6-disulfonic acid (5-NO2-PAH) and cationic surfactant to form 1:2 ionic association complex in a weakly basic medium (pH 9.44),The determination conditions and the mechanism were discussed,The method has been appliced to the analysis of wastewater and moat water samples.     

Automated Parallel Temperature Optimization and Determination of Activation Energy for the Living Cationic Polymerization of 2‐Ethyl‐2‐oxazoline

Sixteen parallel polymerization reactions of 2‐ethyl‐2‐oxazoline have been performed at different temperatures in an automated synthesizer that allowed individual heating of each reactor. During the reactions samples were taken automatically, which were characterized by means of both online GPC and offline GC, in order to optimize the reaction temperature and to determine the activation energy of the polymerization.

     

Cationic Reverse Micelles Create Water with Super Hydrogen‐Bond‐Donor Capacity for Enzymatic Catalysis: Hydrolysis of 2‐Naphthyl Acetate by α‐Chymotrypsin

Reverse micelles (RMs) are very good nanoreactors because they can create a unique microenvironment for carrying out a variety of chemical and biochemical reactions. The aim of the present work is to determine the influence of different RM interfaces on the hydrolysis of 2‐naphthyl acetate (2‐NA) by α‐chymotrypsin (α‐CT). The reaction was studied in water/benzyl‐n‐hexadecyldimethylammonium chloride (BHDC)/benzene RMs and, its efficiency compared with that observed in pure water and in sodium 1,4‐bis‐2‐ethylhexylsulfosuccinate (AOT) RMs. Thus, the hydrolysis rates of 2‐NA catalyzed by α‐CT were determined by spectroscopic measurements. In addition, the method used allows the joint evaluation of the substrate partition constant K_p between the organic and the micellar pseudophase and the kinetic parameters: catalytic rate constant k_cat, and the Michaelis constant K_M of the enzymatic reaction. The effect of the surfactant concentration on the kinetics parameters was determined at constant W₀=[H₂O]/[surfactant], and the variation of W₀ with surfactant constant concentration was investigated. The results show that the classical Michaelis–Menten mechanism is valid for α‐CT in all of the RMs systems studied and that the reaction takes place at both RM interfaces. Moreover, the catalytic efficiency values k_cat/K_M obtained in the RMs systems are higher than that reported in water. Furthermore, there is a remarkable increase in α‐CT efficiency in the cationic RMs in comparison with the anionic system, presumably due to the unique water properties found in these confined media. The results show that in cationic RMs the hydrogen‐bond donor capacity of water is enhanced due to its interaction with the cationic interface. Hence, entrapped water can be converted into “super‐water” for the enzymatic reaction studied in this work.     

DSC法研究液晶物质2-(4-烷氧苯基)6-取代苯并噻唑的相变热性质

The phase transitions of a new group of mesogens, 2-(4-alkoxyphenyl)-6-substituted benzothiazoles were thermodynamically studied by DSC, and their transition temperatures and enthalpy changes were measured, from which the transition entropy changes were calculated. The results obtained were discussed. In addition, the phe-nomenon of super-cooling of the compounds were quantitatively observed.