硫酸羟胺与水合肼对B-Z反应的影响

化学振荡与生化、生理现象关系密切，有维生素C参与的化学振荡反应也很引人注目．赵学庄等对维生素C存在的B－Z反应的振荡行为与机理进行了研究．他们的实验表明，当加入维生素C时，B-Z反应的诱导期增长，振荡周期增大，振荡寿命缩短，与向反应体系加入等量的Br-所产生的影响是一致的，并由此推断，维生素C对B－Z反应的影响可能是由维生素C与BrO反应生成Br-抑制了此反应的化学振荡，据此，凡是能与BrO反应生成Br-的物质，其对B－Z反应的影响必将类似于维生素C，硫酸羟胺与水合肼就属于此类物质．本文初步研究了它们对B－Z反应的影…     

基于加压毛细管电色谱-激光诱导荧光联用技术研究离子强度对维生素B_2光解反应的影响

基于加压毛细管电色谱-激光诱导荧光检测法建立了分析维生素B2及其荧光性光解产物的方法,并用于研究维生素B2在水溶液和磷酸盐缓冲液中的光解反应速率与离子强度之间的关系。发现在C18毛细管色谱柱,流动相为含0.1%(v/v)三氟乙酸的乙腈水溶液,梯度洗脱,激发波长为488 nm,发射波长为520 nm的条件下,维生素B2及多种荧光性光解产物均得到很好的分离和检测,维生素B2的定量限为5×10-8mol/L。在此基础上研究了维生素B2的光降解反应受光照时间和离子强度等的影响。发现离子强度对维生素B2溶液的光解反应有显著影响,离子强度越大,光解速度越快。并进一步通过动力学计算得到维生素B2在水溶液和磷酸盐缓冲液中光解反应的表观速率常数。该研究为维生素B2的光稳定研究提供了一种高效分离和检测的方法,并为维生素B2的保存及临床使用提供了参考。     

苯酚与溴水和氯化铁反应溶液最佳浓度的选择

高中化学教材第二册（人教版）学生实验九“苯酚的性质”：4、在试管里滴2滴苯酚稀溶液再加4mL水,振荡,然后逐滴滴加饱和溴水,直到有白色浑浊现象出现为止。5、在试管里滴人几滴苯酚稀溶液,再加约3mL水,振荡,然后逐滴滴入FeCl3溶液观察现象。这两个反应都属于灵敏反应,如果溶液浓度合适,实验现象就很明显。但是,在我们指导学生实验的过程中发现了如下一些问题。     

趣味药物化学小实验3则

1　维生素 C趣味小实验1 .1　实验内容取规格为 0 .5g、2 m L的维生素 C注射液 ,用玻璃棒将药剂瓶上端敲破 ,将维生素 C溶液全部转移入一支大试管中 ,并在其中加入 8m L蒸馏水 ,振荡 ,使混合均匀。将上述溶液平均分装入 A、B、C、D、E、F6支小试管中 ,然后将小试管排在试管架上。在 A试管中滴加紫色 KMn O4 溶液 ,溶液立即褪色。在 B试管中滴加溴水 ,溴水颜色迅速消失。在 C试管中滴加碘水 ,碘水很快褪色。在 D试管中滴加 Ag NO3溶液 ,试管中立即出现大量黑色沉淀 ;再在试管中滴加30 % H2 O2 溶液 ,试管中立即有大量气体产生 ;将…     

维生素C氧化反应的研究: H2O2-Cu^2^+-磷酸体系中的反应动力学

研究了在铜离子存在时的弱酸性条件下, 用过氧化氢氧化维生素C, 并用直接分光光度法测定未变化的酸, 表明维生素C的催化氧化是以链式反应机制进行的.     

10%维生素C溶液贮存期的理论研究

以维生素C及常用于其注射液中作稳定剂的焦亚硫酸钠为例, 测定了两组平行反应(维生素C无氧降解和有氧降解; 维生素C和焦亚硫酸钠的氧化反应)的动力学参数, 建立了维生素C的降解动力学方程. 结果表明维生素C无氧降解为零级反应; 在维生素C和焦亚硫酸钠的氧化反应中, 维生素C和焦亚硫酸钠的反应级数都为零, 溶解氧为一级; 维生素C溶液的吸光度变化在一定范围内和浓度降解量成线性关系. 根据建立的动力学方程, 从理论上计算得在维生素C溶液中加(或不加)焦亚硫酸钠时的贮存期分别为444 d(或152 d), 表明加入焦亚硫酸钠能显著延长维生素C溶液的贮存期.     

基于非共价键作用的二嵌段共聚物/均聚物超分子体系的自组装行为

采用实空间求解的自洽场理论,研究了两亲性二嵌段共聚物(AB)/均聚物(C)超分子体系在溶液中的自组装行为,其中B疏水嵌段的自由末端与C均聚物的一个末端形成可逆的非共价键.在稀溶液中,AB/C超分子聚合物体系通过自组装形成了一系列不同形貌的胶束,如核-壳-冠的三层胶束和蠕虫状胶束等.研究发现,胶束形貌受到非共价键强度和初...     

电导法测定维生素C注射液的含量

建立了电导法测定维生素C含量的方法.实验表明,在温度15～35℃,浓度为1.0～5.0 g·L-1条件下,溶液浓度与电导率呈良好的线性关系(R值在0.9982～0.9999之间),方法平均回收率达99.2%,精密度(RSD)为0.01%.该法简便、快捷、准确、重现性好,可用于维生素C注射液含量的测定.     

离子液体吸附剂对木犀草素的富集及CARS变量筛选的近红外光谱分析方法

该文以咪唑型离子液体作为原料制备吸附剂富集稀溶液中的木犀草素,利用竞争性自适应权重(CARS)变量筛选的方法建立了一种快速测定木犀草素的近红外光谱分析方法。考察了吸附剂用量、pH值、振荡时间对吸附效果的影响,并探究了吸附剂的吸附能力;富集木犀草素的吸附剂经近红外漫反射光谱检测,采用CARS变量筛选的方法结合偏最小二乘回归(PLS)建立了木犀草素的定量校正模型。结果表明,吸附剂用量为0.15 g、pH值为7、振荡时间为20 min的最佳条件下,吸附率达90.9%,且该吸附符合Langmuir等温吸附模型,最大吸附量为7.1 mg/g。近红外光谱建模中,与未经CARS变量筛选处理作为对照,对比发现经CARS变量筛选的方法结果更优,并采用连续小波变换(CWT)的光谱预处理进行验证,结果表明经CWT处理后,预测残差(RPD)值增大,说明了模型的可靠性。该方法可有效富集稀溶液中的木犀草素,采用CARS变量筛选结合CWT光谱预处理的近红外光谱方法可实现对稀溶液中木犀草素的灵敏、快捷检测。     

1995年全国化学竞赛试题

某橙黄色粉末状固体A,放入稀硝酸中加热,可以看到在无色溶液B中产生一种棕黑色沉淀C。取出无色溶液通入硫化氢气体,有黑色沉淀D析出,此沉淀用水洗净后放入过氧化氢溶液中摇荡,会见到渐渐转变为白色沉淀E;这种白色沉淀可溶于过量氢氧化钠溶液而成为无色溶液,在其中通入氯气有棕黑色沉淀生成,这种棕黑色沉淀和上述沉淀C有相同性质:与浓盐酸作用会产生黄绿色气体;在稀硝酸中与硫酸锰稀溶液作用会生成紫红色溶液。     

一类新型光化学振荡体系的研究

三个三苯甲烷类、九个变色酸双偶氮类共十二个水溶液体系中, 用HP-8451型快速扫描光度计, 在体系不搅拌、控制浓度和温度情况下, 可以记录到衰减式规整的周期振荡波。辐射开抬后出现1000s以上的振荡前置期, 振荡主期的周期为112±5s,最大振幅约为0.06A。搅拌时光化学反应为零级。本文还研究了浓度、温度和搅拌对形成光化学振荡影响, 讨论了它们的可能机制。此十二个振荡体系末见文献报道。     

Production of organometallic polymers by the interfacial technique. XXVII. Reaction variables in the synthesis of poly[oxy(dicyclopentadienylzirconium)oxycarbonylferrocenylcarbonyl]

The synthesis of poly[oxy(dicyclopentadienylzirconium)oxycarbonylferrocenylcarbonyl] was studied as a function of several reaction variables. Yield varied greatly with pH, reaching a maximum around pH = 7.5; yield was greater for systems employing a saturated aqueous solution of the disodium 1,1′-ferrocene dicarboxylate falling rapidly to a plateau; yield attained a maximum as the aqueous volume was varied but decreases throughout the range studied as the volume of CHCl₃ increases; a plateau in yield was reached at around a stirring rate of 20,700 rpm. For more dilute solutions (6.7 × 10^?3M) yield is dependent on the concentration of both reactants and seeks a maximum around a stirring time of 30 sec.     

NiL(ClO4)2催化NaBrO3-MA-H3PO4体系振荡反应的研究

报道了一种反式Curtis环的镍(Ⅱ) 的配合物NiL(ClO4)2(L为2,4,4,9,11,11-六甲基-1,5,8,12-四氮杂环十四-1,5,8,12-四烯)催化NaBrO3-CH2（COOH）2（MA）-H3PO4体系的化学振荡反应。测得该体系的振荡范围,研究、分析了各物种浓度、自由基抑制剂和还原剂、Ag+、Hg2+以及温度对振荡反应的影响。结果表明Br-起重要动力学控制作用,在反应过程中有自由基、Br2产生并参与了反应。同时发现搅拌速度对反应有很大影响。该反应的振荡轨迹与经典BZ反应及其它四氮杂大环配合物催化的体系有所不同。     

Belousov-Zhabotinskii反应的研究——不同气氛下的振荡现象

本文考察了不同气氛下, 丙二酸(MA)、邻菲罗啉亚铁离子和溴酸根之间反应的振荡现象。结果表明, 氢气与氮气对此反应的振荡基本上是惰性的, 而氧气对此反应的振荡有明显的影响。对氧的影响作了较仔细的研究, 观察到氧气氛下反应出现的一些特殊振荡波形。此外还对邻菲罗啉亚铁离子的离解造成的影响作了初步探讨。结合熟知的反应机理对实验结果进行了若干分析。     

界面缓蚀剂的吸附稳定性

研究表明：在一定条件下,阳极脱附电位可作为评价缓蚀剂吸附稳定性的一个经验参数：缓蚀剂吸脱附诱导的电化学振荡是缓蚀体系的一种特殊失稳状态,即缓蚀剂吸附过程与电极反应中间吸附态产物耦合的结果;卤素离子的协同作用不仅可以提高某些有机缓蚀剂的吸附复盖度,而且可以增强其吸附稳定性;微分极化曲线是研究吸附稳定性的有效方法。     

搅拌对Belousov-Zhabotinskii振荡反应的影响及反应机理研究

研究了非流动条件下搅拌对B-Z振荡反应的影响。实验发现即使在氮气保护下, 搅拌仍对振荡行为(振幅和周期等)有明显影响。为解释搅拌的影响作用, 对B-Z反应的Oregonator模型作了修正和补充并依据非平衡态热力学的一般原理将搅拌影响唯象地归结为反应速率常数的相对变化。修正后的模型不仅较好地克服了原模型存在的一些问题, 而且在引入搅拌作用以后得到了与实验现象定性一致的数值模拟结果。     

Nonlinear chemical reaction between Na_2S_2O_3 and Peroxide compound

Kinetics of reaction between Na2S2O3 and peroxide compound ( H2O2 or Na2S2O8) in a batch reactor and in a continuous stirring tank reactor (CSTR) were studied.Steady oscillations in uncatalyzed reactions in a CSTR were first discovered.In Na2S2O3-H2O2-H2SO4 reaction system,Pt potential and pH of higher and lower flow rutes beyond oscillation flow rates were in around the same extreme values.The reaction catalyeed by Cu2+ corsist of the catalyzed oscillation process and the uncatalyzed osciliation one.On the basis of experiment,a reaction mechanism consisting of three stages was put forward.The three stages are H positive-feedback reactions,proton negative-feedba k (uncatalyzed negative-feedback and catalyzed negative-feedback) reactions and transitional reactions.The mechanism is able to explain reasonably the nonlinear chemical phenomena appearing in the thiosulfatc oxidation reaction by peroxide-compounds.     

Collective behavior of a population of chemically coupled oscillators

Experiments are performed in which a large number (approximately 10(4)) of relaxation oscillators are globally coupled through the concentration of chemicals in the surrounding solution. Each oscillator consists of a microscopic catalyst-loaded particle that displays oscillations in the concentrations of chemical species when suspended in catalyst-free Belousov-Zhabotinsky (BZ) reaction solution. In the absence of stirring, the uncoupled particles display a range of oscillatory frequencies. In the well-stirred system, oscillations appear in the surrounding solution for greater than a critical number density of particles (n(crit)). There is a growth in the amplitude of oscillations with increasing n, accompanied by a slight increase or no change in frequency. A model is proposed to account for the behavior, in which the transfer of activator and inhibitor to and from the bulk medium is considered for each particle. We demonstrate that the appearance and subsequent growth in the amplitude of oscillations may be associated with partial synchronization of the oscillators.     

Dependence of turbidity oscillations of self-oscillating polymers on the selective recognition of the crown ether receptors contained in the polymer chain

The turbidity oscillations of self-oscillating polymers in the Belousov-Zhabotinsky (BZ) reaction system depending on the crown ether receptors contained in the polymer network have been studied. The three monomers are copolymerized, namely, N-isopropylacrylamide, the metal catalyst monomer for the BZ reaction, and the crown ether receptor monomer, to prepare the self-oscillating polymers used in this study. The turbidity oscillations are characterized by monitoring the transmittance of the polymer solution in the BZ reaction system at a specific wavelength of 570 nm. The oscillations are varied by crown ether receptors used in the polymerization process, i.e., BCAm(6) or BCAm(5), for the selective recognition of specific cations between potassium and sodium ions in the solution. The selective recognition of the BCAm receptors in the polymer chain for the two ions has brought out a variation in the turbidity oscillations by a change in the hydrophilicity of the polymer chain. The oscillations of the polymer solution composed of the BCAm(5) receptor are more influenced by sodium ion, while the polymer solution of BCAm(6) receptor is affected by potassium ion. However, the oscillation patterns of the redox changes obtained by these solution systems look much alike despite the differences in the polymer chain by crown ether receptors and cations of bromate used for the BZ reaction.     

REVERSIBLE PHOTODIMERIZATION OF ANTHRACENE AND TETRACENE

Abstract— Dianthracene is efficiently photodissociated, forming anthracene with a quantum yield of about 0.63. Like anthracene, tetracene undergoes a reversible photochemical reaction, the product of which appears to be di-tetracene. In dilute, deoxygenated solutions the of quantum yeild for the formation of di-tetracene is directly proportional to the concentration of the monomer ødim = 2.2 (). The quantum yield for the reverse reaction is approximately 0.74
When dilute deaerated solutions of anthracene are irradiated with the unfiltered radiation from a quartz-mercury arc, a degradation product is formed. Unlike the dimer, this product cannot be converted into anthracene either by heating it to 200C or by irradiating it in solution with light of 254 nm. This degradation product appears to be the compound or compounds which Birks et al. believed to be dianthracene. Irradiation of deaerated solutions of anthracene (or tetracene) with light of wavelenghts longer than 300 nm produces only the dimer, which has an absorption spectrum similar to that reported by Coulson et al.