2,4-二硝基氯苯碱性水解胶团催化的活化能

研究了阳离子表面活性剂氯化十六烷基吡啶(CPC)和十六烷基三甲基氯化铵(CTAC)胶团对2,4-二硝基氯苯(DNCB)碱性水解的催化作用和小分子极性有机物丁醇的加入对该反应的影响,计算了反应活化能.结果表明:(1)CPC和CTAC胶团对DNCB碱性水解都有明显的催化作用;(2)加入少量叔丁醇略有利于提高催化效果;(3)在CPC和CTAC胶团溶液中DNCB碱性水解反应的活化能约为49kJ/mol,比纯水中的91kJ/mol低得多,说明反应机制可能存在差异.     

有机膨润土的吸附性能研究

有机膨润土处理水中有机物的研究已有报道［1－4］，但尚无就改性所用的表面活性剂对有机膨润土吸附性能的影响及规律的系统研究，对有机膨润土与不同有机物间作用机理的报道也甚少［1］．本文用3种不同的阳离子表面活性剂改性膨润土，并从等温吸附线的特征和有机物的辛醇－水分配系数较系统地研究了有机膨润上对几种有机物的吸附性能和作用机理．1实验部分1．1材料原士为钠基膨润土，经测定其阳离子交换容量为7464meg／100g土；澳化十六烷基王甲铰（CTMAB）为分析纯，溪化十二烷基三甲铰（DTMAB，95％），演化十八烷基三甲按（OTMAB…     

有机生色团/SiO_2-TiO_2二阶非线性光学杂化材料的研究

以分散橙－3（DO－3）与γ－缩水甘油氧与基三甲氧基硅烷（KH－560）反应 得到的功能性生色团ASD为前体，采用溶胶－凝胶（sol-gel）法使ASD与钛酸四正 丁酯在酸性条件下共水解缩合，合成了新型稳定的有机生色团/SiO_2-TiO_2杂化溶 胶，并对该溶胶体系的相图进行了研究。利用傅立叶红外（FTIR）、透射电镜（ TEM）和X射线能量色散谱仪（EDS）研究了杂化溶胶形成过程中的络合机理及溶胶 形态。由一维刚性取向气体模型计算杂化材料膜的二阶非线性光学（NLO）系数X~ (2) is 1.43 * 10~(-7) esu。差示扫描量热法（DSC）测得杂化材料的玻璃化温度 可达196 ℃；用紫外－可见光谱对杂化膜在极化前后的取向及取向稳定性进行了研 究。     

甲酰胺与正负离子表面活性剂有序溶液的研究

对羧酸钠与烷基三甲基溴化铵1：1混合体系的研究表明：常温下各体系在不同比例甲酰胺（FA）／水混合溶剂中，表面张力随浓度变化均有明显的转折点，显示了混合体系中胶团的存在．实验中发现随混合溶剂中FA比例增加，各体系的临界胶团浓度（cmc）增大．在较高温度下发现在甲酰胺中亦存在着因胶团形成而产生的表面张力-浓度对数（γ－logc）曲线的转折点，利用相分离模型对体系胶团热力学参数进行了计算．并探讨了FA对正负离子表面活性剂囊泡的影响．     

钛硅分子筛催化气相环己酮肟贝克曼重排反应

 对比研究了具有MFI结构的TS－1，silicalite－1，Al－ZSM－5和B－ZSM－5分子筛对气相环己酮肟贝克曼重排反应的催化性能．结果显示，TS－1适宜用作重排反应的催化剂，而含骨架B或Al的ZSM－5分子筛的催化性能较差，表明将Ti引入至sili－calite－1有利于改善其对环己酮肟重排反应的催化性能．反应氛围（溶剂、载气和原料添加物）对TS－1催化性能的影响规律说明，弱酸性气体的存在有利于TS－1对环己酮肟的活化与己内酰胺的选择性生成．优化的反应氛围包括以甲醇或乙醇为溶剂，二氧化碳为载气，以及醋酸为原料添加物．     

非离子表面活性剂的吸附机理和表面胶团化对二氧化硅悬浮…

测定了ＣＡＢ－Ｏ－ＳＩＬ在２９０．７Ｋ和３０４．２Ｋ时自水和１ｍｏｌ／ＬＮａＣｌ溶液中吸附非离子表面活性剂ＴｒｉｔｏｎＸ－１００（ＴＸ１００）的吸附等温线，结果表明，吸附量随温度升高而增加，ＮａＣｌ的存在也使吸附量增加，运用生成表面胶团的吸附理论处理了实验结果，求得了表面胶团化的平衡常数，表面胶团的平均聚集数，临界表面胶团浓度和表面胶团化的标准热力学函数，实验表明，随ＴＸ１００浓度的增大，ＣＡＢ－     

苯酚、正丁醇、β-环糊精、1-溴代萘四元包络物室温燐光光谱及分析应用

研究了在含有正丁醇（n－Bu）的猓泛ㄢ－CD）溶液中,加入有机小分子苯酚(phenol)后诱导1－溴代萘（1－BrN）发射强的室温光（RTP）的光谱性质。实验表明所研究体系中形成了1－BrN/猓瑿D/n－Bu/phenol四元包络物。考察了利用该体系测定痕量1－BrN的定量方法的可行性,结果发现1－BrN的线性范围为：1.0×10―5―1.0×10－4mol/L,其检出限为6.02×10－9mol/L。     

两相催化体系中长链烯烃氢甲酰化反应研究：—阳离子胶束的动力学作用机理

研究了以水溶性铑－膦配合物RhCl(CO)(TPPTS)2为催化剂,三苯基膦三磺酸钠（TPPTS）为配体,在阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）存在下,水／有机物两相催化体系中,1－十二烯甲酰化反应与CTAB浓度的关系,为了进一步揭示阳离子表面活性剂在该反应体系中的动力学作用机理,分别应用分光光度法和光散射法,测定了1－十二烯在CTAB胶束中的增溶曲线和铑民位催化剂、配体TPPTS和1－十二烯对CTAB胶束摩尔质量的影响,结果表明,阳离子表面活性剂对长烯烃烯氢甲酰化两相催化反应具有加速作用,可能是由于;（1）催化剂及配体吸附于胶束界面并富集;（2）烯烃增溶于胶束内核,容易与催化活性物种发生配位反应。     

有机化学总复习

有机化学总复习应达到从结构、性质、制备掌握烃及烃的衍生物的衍变关系;设计多种类型实验,掌握重要有机物的特征反应和检验;熟悉有机化学在生产、生活中的应用;掌握有机物组成、结构的推测和计算等五项要求。为此,可以从以下五个方面进行复习: 1.狠抓“结构”主线,突出有机化学知识的内在联系。包括:掌握有机物分类及同分异构体的书写;理解反应原理,掌握有机物性质;抓住原子(原子团)间的相互影响,了解性质异同的原因;以官能团衍变关系为主线,掌握有机物的衍变关系等; 2.准确掌握基本概念和化学用语; 3.注意反应试剂与条件,掌握有机反应; 4.设计实验,再现重要特征反应; 5.提高学生有机化学计算的解题能力。     

溴化十二烷基吡啶的吸附和表面胶团化对二氧化硅悬浮液稳定性的影响

研究了阳离子表面活性剂溴化十二烷基吡啶（ＤＰＢ）的吸附和表面胶团化对二氧化硅（ＣＡＢ－Ｏ－ＳＩＬ）悬浮液稳定性的影响，以及加入电解质的效应．结果表明：ＤＰＢ在ＣＡＢ－Ｏ－ＳＩＬ上的吸附等温线呈双平台（或ＬＳ）型，溴化钠（０．１ｍｏｌ／Ｌ）的存在使吸附等温线向低浓区移动，第二平台的饱和吸附量增大，但基本不影响第一平台的吸附量，这些结果都与涉及形成表面胶团的二步吸附模型相符．当ＤＰＢ浓度很低时，ＣＡＢ－Ｏ－ＳＩＬ悬浮液的稳定性随ＤＰＢ浓度的增大而下降；当ＤＰＢ浓度增至ｓｍｃ（临界表面胶团浓度）附近时，悬浮液稳定性急剧提高．ＮａＢｒ的存在，并不影响上述悬浮液稳定性规律．利用表面活性剂的二步吸附和颗粒相互作用模型，并结合ＤＰＢ吸附等温线的研究结果，可以合理地解释ＣＡＢ－Ｏ－ＳＩＬ悬浮液稳定性的实验结果．     

循环流动固定床光催化反应器动力学数学模拟

以甲基橙为模型反应物,研究了连续循环固定床光催化反应器的动力学过程.根据光催化氧化过程特点,分析并建立了准一级反应动力学方程,对该反应系统的动力学过程进行动态数学模拟,用四阶Runge-Kutta法进行数值计算,结果表明数学模拟与实验数据相吻合.在该光催化反应体系中,处理量增加时实际反应速率常数k基本不变,而表观反应速率常数kapp变小,二者之间关系与反应器体积对处理量体积比（γ）密切相关;反应速率常数受起始浓度影响很大,在15～150 μmol•L－1浓度范围内,lnk=－0.48ln[c0]＋1.42;反应速率常数与光强的关系为k∝I0.5;反应速率常数受溶液pH值的影响也很大.     

Mechanism of photocleavage of (coumarin-4-yl)methyl esters

(Coumarin-4-yl)methyl esters (CM-A) are caged compounds that, upon excitation, release the masked biologically active acid HA and the highly fluorescent (coumarin-4-yl)methyl alcohol CM-OH very rapidly and in part with high efficiency. The results of photostationary and time-resolved investigations of 25 CM-A esters and corresponding CM-OH alcohols with varying substitution on the (coumarin-4-yl)methyl moiety and a wide variation in the structure of the acidic part have been analyzed. The initial step of the photoreaction is heterolytic ester cleavage leading to the singlet ion pair 1[CM+ A-] with rate constant k1. 1[CM+ A-] hydrolyzes to CM-OH and HA with rate constant k2 or recombines to ground-state CM-A with rate constant krec. 1[CM+ A-] is the key intermediate of the reaction. Stabilization of both CM+ by using electron-donating substituents and A- by increasing the acid strength leads to a strong enhancement of k1 and simultaneously to a diminution of krec. Therefore, stabilization of the ion pair has a two-fold positive effect on the photocleavage of (coumarin-4-yl)methyl esters: increasing the rate of the initial reaction step, which might require less than 30 ps, and increasing the efficiency of product formation.     

Oxidation of alcohol by lipopathic Cr(VI): a mechanistic study

The oxidation kinetics of various aliphatic primary and secondary alcohols having varied hydrocarbon chain length were studied using cetyltrimethylammonium dichromate (CTADC) in dichloromethane (DCM) in the presence of acetic acid and in the presence of a cationic surfactant. The rate of the reaction is highly sensitive to the change in [CTADC], [alcohol], [acid], [surfactant], polarity of the solvents, and reaction temperature. A Michaelis-Menten type kinetics was observed with respect to substrate. The chemical nature of the intermediate and the reaction mechanism were proposed on the basis of (i) observed rate constant dependencies on the reactants, that is, fractional order with respect to alcohol and acid and a negative order with respect to oxidant, (ii) high negative entropy change, (iii) inverse solvent kinetic isotope effect, k(H2O)/k(D2O) = 0.76, (iv) low primary kinetic isotope effect, kH/kD = 2.81, and (v) the k(obs) dependencies on solvent polarity parameters. The observed experimental data suggested the self-aggregation of CTADC giving rise to a reverse micellar system akin to an enzymatic environment, and the proposed mechanism involves the following: (i) formation of a complex between alcohol and the protonated dichromate in a rapid equilibrium, equilibrium constant K = 5.13 (+/-0.07) dm(3) mol(-1), and (ii) rate determining decomposition (k(2) = (7.6 +/- 0.7) x 10(-3) s(-1)) of the ester intermediate to the corresponding carbonyl compound. The effect of [surfactant] on the rate constant and the correlation of solvent parameters with the rate constants support the contribution of hydrophobic environment to the reaction mechanism.     

Kinetics of dissociation of tris-(2,2'-bipyridyl) iron(II) in water solubilized by Triton X-100 reverse micelles

The dissociation of tris-(2,2'-bipyridyl) iron(II) ([Fe(bipy)3]2+) has been studied in the Triton X-100/hexanol/cyclohexane reverse micellar medium. The reaction obeys simple first-order kinetics with no evidence of autoinhibition. The first-order rate constant (k1) has been determined at different values of W ([H2O]/[Triton X-100]). The rate (k1) decreases with increasing value of W. k1 also increases with increase in Triton X-100 concentration at constant values of W, showing that the reaction takes place at greater speed at the micellar interface. The kinetic results can be interpreted by the monomolecular pseudo-phase model. The effect of W on rate (k1) is more pronounced in the range of W from 1.55 to 4.2 but less pronounced at higher W. The reaction is further accelerated by Cl- and SCN- ions and the kinetic results provide evidence for the formation of ion pairs between the cation [Fe(bipy)3]2+ and each of these anions. The formation of such ion pairs has not been observed in aqueous medium but has been reported earlier in aqueous-alcohol mixtures. This result therefore provides evidence for the lower micropolarity of solubilized water compared to ordinary water.     

1H NMR analysis of the tolylene-2,4-diisocyanate – methanol reaction

<正>Tolylene-2,4-diisocyanate(2,4-TDI) 1 reacts with methanol through two simultaneous paths in the polyurethane reaction,which involve two different intermediates-tolylene-4-carbamatic-2-isocyanate 2 and tolylene-2-carbamatic-4-isocyanate 3,and the final product is tolylene-2,4-dicarbamate 4.The-CH_3 chemical shifts in benzene ring in compounds 1,2,3 and 4 can be easily tested and well distinguished,through which those four compounds are quantified and their kinetics are investigated.It shows that four rate constants for the tolylene-2,4-diisocyanate-methanol reaction in CCl_4 at 50℃are k_1=9.6×10~(-2)h~(-2)mol~(-2)min~(-1), k_2=1.4×10~(-2)h~(-2)mol~(-2)min~(-1),k_3=4.0×10~(-3)h~(-2)mol~(-2)min~(-1),k_4=1.4×10~(-3)h~(-2)mol~(-2)min~(-1).(k_1 is the reaction rate constant from compounds 1 to 2;k_2 is the reaction rate constant from compounds 1 to 3;k_3 is the reaction rate constant from compounds 3 to 4;k_4 is the reaction rate constant from compounds 2 to 4).     

Solvent effects on the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. A laser flash photolysis study

[reaction: see text] A laser flash photolysis study has been carried out to assess solvent effects on the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. The rearrangement rate constant k decreases by increasing solvent polarity and an excellent correlation with negative slope is obtained between log k and the solvent polarity parameter E(T)N. These evidences are in full agreement with the previous indication that the extent of internal charge separation decreases on going from the starting 1,1-diarylalkoxyl radical to the transition state.     

Pressure effect on the nonradiative process of thioflavin-T

Time-resolved emission techniques were employed to study the nonradiative process of thioflavin-T (ThT) in 1-propanol, 1-butanol, and 1-pentanol as a function of the hydrostatic pressure. Elevated hydrostatic pressure increases the alcohol viscosity, which in turn strongly influences the nonradiative rate of ThT. A diamond-anvil cell was used to increase the pressure up to 2.4 GPa. We found that the nonradiative rate constant, k(nr), decreases with pressure. We further found a remarkable linear correlation between a decrease in k(nr) (increase in the nonradiative lifetime, τ(nr)) and an increase in the solvent viscosity. The viscosity was varied by a factor of 1000 and k(nr) was measured at high pressures, at which the nonradiative rate constant of the molecules decreased from (7 ps)(-1) to (13 ns)(-1), (13 ps)(-1) to (17 ns)(-1) and (17 ps)(-1) to (15 ns)(-1) for 1-propanol, 1-butanol, and 1-pentanol, respectively. The viscosity-dependence of k(nr) is explained by the excited-state rotation rate of the two-ring systems, with respect to each other.     

Flash photolytic generation and study of p-quinone methide in aqueous solution. An estimate of rate and equilibrium constants for heterolysis of the carbon-bromine bond in p-hydroxybenzyl bromide

Flash photolysis of p-hydroxybenzyl acetate in aqueous perchloric acid solution and formic acid, acetic acid, biphosphate ion, and tris(hydroxymethyl)methylammonium ion buffers produced p-quinone methide as a short-lived species that underwent hydration to p-hydroxybenzyl alcohol in hydronium ion catalyzed (k(H(+)) = 5.28 x 10(4) M(-1) s(-1)) and uncatalyzed (k(uc) = 3.33 s(-1)) processes. The inverse nature of the solvent isotope effect on the hydronium ion-catalyzed reaction, k(H(+))/k(D(+)) = 0.41, indicates that this process occurs by rapid and reversible protonation of the quinone methide on its carbonyl carbon atom, followed by rate-determining capture of the p-hydroxybenzyl carbocation so produced by water, while the magnitude of the rate constant on the uncatalyzed process indicates that this reaction occurs by simple nucleophilic addition of water to the methylene group of the quinone methide. p-Quinone methide also underwent hydronium ion-catalyzed and uncatalyzed nucleophilic addition reactions with chloride ion, bromide ion, thiocyanate ion, and thiourea. The solvent isotope effects on the hydronium ion-catalyzed processes again indicate that these reactions occurred by preequilibrium mechanisms involving a p-hydroxybenzyl carbocation intermediate, and assignment of a diffusion-controlled value to the rate constant for reaction of this cation with thiocyanate ion led to K(SH) = 110 M as the acidity constant of oxygen-protonated p-quinone methide. In a certain perchloric acid concentration range, the bromide ion reaction became biphasic, and least-squares analysis of the kinetic data using a double-exponential function provided k(Br(-)) = 3.8 x 10(8) M(-1) s(-1) as the rate constant for nucleophilic capture of the p-hydroxybenzyl carbocation by bromide ion, k(ionz) = 8.5 x 10(2) s(-1) for ionization of the carbon-bromine bond of p-hydroxybenzyl bromide, and K = 4.5 x 10(5) M(-1) as the equilibrium constant for the carbocation-bromide ion combination reaction, all in aqueous solution at 25 degrees C. Comparisons are made of the reactivity of p-quinone methide with p-quinone alpha,alpha-bis(trifluoromethyl)methide as well as p-quinone methide with o-quinone methide.     

Kinetic and theoretical studies on alkaline ethanolysis of 4-nitrophenyl salicylate: effect of alkali metal ions on reactivity and mechanism

Pseudo-first-order rate constants (k(obsd)) for reactions of 4-nitrophenyl salicylate (7) with alkali metal ethoxides (EtOM, M = K, Na, and Li) in anhydrous ethanol have been measured spectrophotometrically. Interestingly, the k(obsd) value decreases significantly as the concentration of EtOM increases. Because the phenolic moiety of substrate 7 would be deprotonated and exist as an anionic form (i.e., 7(-)) under kinetic conditions, the ground-state stabilization of 7(-) through formation of a six-membered cyclic complex with M(+) (i.e., 8) is proposed to be responsible for the decreasing k(obsd) trend. The k(obsd) value at a given concentration of EtOK increases steeply upon addition of [18]crown-6 ether (18C6) up to [18C6]/[EtOK] = 1 in the reaction mixture and then remains relatively constant thereafter. In contrast, k(obsd) decreases upon addition of salts (e.g., LiClO(4) or KSCN) to the reaction mixture, which indicates that M(+) ions inhibit the reaction. However, in the presence of 18C6, the k(obsd) value is independent of the concentration of EtOK but remains constant, which indicates that the reaction proceeds through a unimolecular mechanism in the presence of the complexing agent. Although two conceivable unimolecular pathways (formation of ketene 9 and lactone 10) can account for the kinetic results, the reaction has been concluded to proceed via formation of ketene 9 as the reactive intermediate on the basis of theoretical calculations.     

Kinetik der unkatalysierten Urethanbildung

Summary The kinetics of the reaction of phenylisocyanate with 1-butanol have been studied at low concentrations in carbon tetrachloride solution at three temperatures. The present paper describes the relation between the reaction rate and the concentration of the alcohol dimer and the 1:1 alcoholurethane associate. Therefrom we conclude that the monomeric alcohol does not play any significant part in the reaction. We explain the observed rate equation with the second-order term of the reactants with the equality of the productsk _AA K _AA andk _AU K _AU (rate constant and association constant of alcohol dimer and 1:1 alcohol-urethane associate).For the reaction of alcohol dimer H =45.4 kJ mol^–1 and S =– 142J mol^–1K^–1. We interpret this result in terms of a six-cyclic transition state.