抗氧剂亚硫酸钠、亚硫酸氢钠及焦亚硫酸钠氧化反应速率常数的测定

为评价抗氧剂的抗氧化能力, 测定了抗氧剂亚硫酸钠、亚硫酸氢钠及焦亚硫酸钠在水溶液中与氧反应的速率常数. 在溶液中连续通入足量的氧气, 维持溶解氧浓度恒定. 用碘量法测定亚硫酸钠、亚硫酸氢钠及焦亚硫酸钠在水溶液中不同时刻的浓度, 用氧电极测定溶液中溶解氧的浓度, 作出亚硫酸钠、亚硫酸氢钠及焦亚硫酸钠的降解曲线, 计算亚硫酸钠、亚硫酸氢钠及焦亚硫酸钠氧化反应速率常数. 结果表明, 亚硫酸钠、亚硫酸氢钠及焦亚硫酸钠在水溶液中与氧的反应均为零级反应. 由于在溶液中这三种抗氧剂存在解离平衡, 当溶液的pH值相同时这三种抗氧剂实质上是一样的, 其平均表观反应速率常数在25 ℃温度和pH 6.8, 4.0及9.2条件下分别为(1.34±0.03)×10^－3, (1.20±0.02)×10^－3和(6.58±0.02)×10^－3 mol•L^－1•h^－1.     

Oxidative Deselenylation with Sodium Perborate and Sodium Percarbonate

In the presence of acetic anhydride, both sodium perborate and sodium percarbonate have been found to be effective reagents for the oxidation of α-phenylselenocarbonyl compounds to α,β,-unsaturated carbonyl compounds.     

Determination of Sodium Tolyltriazole and Sodium Mercaptobenzothiazole in Engine Coolants

Abstract

A high performance liquid chromatography method was developed to quantitatively determine the corrosion inhibitors sodium tolyltriazole and sodium mercaptobenzothiazole in fresh and used ethylene glycol-based engine coolant formulations. Aliquots of coolant, diluted with water and methanol, are analyzed directly. Approximately one-half hour is required to determine both inhibitors with relative standard deviations of about 4%.     

碳酸钠与碳酸氢钠分解温度的热力学估算

运用化学反应的焓变与熵变,从化学热力学的角度,计算说明了如果空气中二氧化碳的含量按文献值即体积浓度为0.03%上下各浮动20%,求得碳酸钠分解温度为1227.69℃和1203.74℃,用酒精灯加热不能达到;碳酸氢钠分解温度为54.56℃和50.9℃,用酒精灯加热很容易达到;故用酒精灯加热只能使碳酸氢钠分解产生二氧化碳,而碳酸钠则不能。     

硅酸钠和硅铝酸钠溶液的研究

本文采用TMS-GC方法研究硅酸钠及硅铝酸钠溶液中硅酸根离子存在状态及其变化,并配合²⁷Al-NMR方法研究铝酸根离子存在状态,从中找出它们的变化规律。     

百里酚蓝鉴别碳酸钠与碳酸氢钠溶液实验的设计与研究

基于碳酸钠、碳酸氢钠溶液的碱性不同,采用适量的百里酚蓝乙醇溶液,设计了可快速、方便、有效地鉴别碳酸钠和碳酸氢钠溶液的方法,并对其进行了理论研究。该方法现象明显,可靠性强,重现性好,成功率高。可应用于食品、药品检测等领域。     

Non-Aqueous Titrimetric Determination of Sulphadimidine Sodium and Sulphadiazine Sodium in Injections

Abstract

The behaviour of sodium salts of two heterocyclic sulphonamide derivatives (Sulphadimidine and sulphadiazine) in non-aqueous titrimetry was studied. Accordingly a simple and accurate procedure for their determination, based on their titration in acetic anhydride-acetic acid solvent system (5:1) with acetous perchloric acid solution is proposed. Results obtained agreed with those of a pharmacopoeial method.     

Bromination of Alkenes Using a Mixture of Sodium Bromide and Sodium Perborate

Bromination of alkenes with sodium bromide in the presence sodium perborate provides a simple, high yield route to dibromoalkanes.     

Creaming and Rheology of Oil-in-Water Emulsions Containing Sodium Dodecyl Sulfate and Sodium Caseinate

The kinetics of bridging flocculation of polystyrene latex (PSL) particles induced by addition of excess polyethylene oxide (PEO) in the initial stage was studied using standardized mixing flow generated in an end-over-end rotation apparatus. To clarify the effect of the rate of polymer supply, flocculation experiments were performed by changing polymer concentration (C(p)). As was found in previous investigation, the progress of flocculation is divided into two stages. The first stage is characterized by an enhancement of the rate of flocculation by polymer addition. The increase in polymer concentration results in a higher enhancement but in a shorter duration for this stage. In the second stage, the flocculation is essentially stopped due to the appearance of steric stabilization. It was found that the ultimate degree of flocculation goes through a maximum against C(p). That is, when C(p)>==1.0 ppm, the ultimate degree of flocculation decreases with increased C(p). In this region, a clear crossover from the first stage to the second stage was observed. In the extreme case, evidence of a slight setback of flocculation was confirmed, which implies the breakup of metastable bridges by the application of additional fluid shear. When C(p)<==1.0 ppm, the ultimate degree of flocculation decreases with decreased C(p). The crossover from the first stage to the second stage appears more gradual at lower C(p). These results were observed irrespective of ionic strength. This result was interpreted as the elimination of a bare surface due to the spreading of a steric layer of adsorbed polymer. The characteristic time for reconformation of the polymer at a bare colloidal surface was estimated to be a few seconds. Copyright 2000 Academic Press.     

十一烯酸钠与十一酸钠水溶液的表面化学

决定表面活性剂性能的首要因素是其分子结构．关于表面活性剂性能随极性头类型、疏水基化学组成、疏水链数目、长度及分支等因素的影响已有许多研究[1]．相比之下，疏水基中含有双键的影响研究较少．实际上，在由两亲分子组成的生物膜中，不饱和脂肪酸酯的存在有重要意义，它使     

The Reaction of 2-Arylvinamindinium Perchlorates with Sodium Borohydride and Sodium Cyanoborohydride

In the last few years, numerous efforts have been directed to the development of acetonylation methods¹. Recent works in this laboratory have shown that O, O-t-butyl and O-isopropenyl peroxycarbonate 1 can be regarded as a good acetonylation reagent; its decomposition in solution results in the substitution of an hydrogen atom by an acetonyl group on each compound Σ-H able to undergo free radical addition reactions to alkenes². The following free radical chain reaction mechanism has been proposed:      

Sodium and potassium pervanadates

Russian Chemical Bulletin -     

钠与苯酚反应速率为何比钠与乙醇反应速率慢

1 问题提出 高中化学新课程苏教版<实验化学>(2006年2月第1版)第25页课题"乙醇和苯酚的性质"中"实验一乙醇、苯酚与金属钠的反应"内容为:"在2支干燥的试管里各加入2 mL乙醚,向其中一支试管中加入1 mL乙醇,向另一支试管中加入约1.5 g苯酚,振荡.     

Facile Stabilization of the Sodium Metal Anode with Additives: Unexpected Key Role of Sodium Polysulfide and Adverse Effect of Sodium Nitrate

Sodium metal is an attractive anode for next‐generation energy storage systems owing to its high specific capacity, low cost, and high abundance. Nevertheless, uncontrolled Na dendrite growth caused by the formation of unstable solid electrolyte interphase (SEI) leads to poor cycling performance and severe safety concerns. Sodium polysulfide (Na₂S₆) alone is revealed to serve as a positive additive or pre‐passivation agent in ether electrolyte to improve the long‐term stability and reversibility of the Na anode, while Na₂S₆‐NaNO₃ as co‐additive has an adverse effect, contrary to the prior findings in the lithium anode system. A superior cycling behavior of Na anode is first demonstrated at a current density up to 10 mA cm^?2 and a capacity up to 5 mAh cm^?2 over 100 cycles. As a proof of concept, a high‐capacity Na‐S battery was prepared by pre‐passivating the Na anode with Na₂S₆. This study gives insights into understanding the differences between Li and Na systems.     

癸基硫酸钠和癸烷磺酸钠与阳离子聚电解质相互作用的差别

 通过表面张力及荧光探针方法, 研究了癸基硫酸钠和癸烷磺酸钠与阳离子聚电解质聚二甲基二烯丙基氯化铵(PDMDAAC)的相互作用. 结果表明, 虽然单一癸基硫酸钠和癸烷磺酸钠性质非常相似, 但它们与PDMDAAC的相互作用有明显差别, 癸基硫酸盐与PDMDAAC的相互作用明显强于癸烷磺酸盐. 通过量子化学计算结果对本文实验观测结果进行了解释.     

亚硝酸钠的毒害及解救

亚硝酸钠是一种用途广泛,但人体摄入过量后能引起严重毒害的物质。亚硝酸钠有强氧化性,能使体内正常的血红蛋白中的两价铁离子氧化成三价铁离子,从而使血红蛋白失去可逆性运送氧气和交换二氧化碳的能力。亚硝酸钠中毒后常出现严重缺氧症状。急救时一般采用洗胃、注射亚甲兰或Vc等措施。这里同样利用氧化还原的原理,即这些药物本身极易氧化,而使三价铁离子还原成两价铁离子,从而恢复血红蛋白的正常生理功能。当然,严重时则需输血,以补充新鲜的血红蛋白。     

Sodium Complexes of Isomaltol and Maltol

Sodium bis(3-O-hydroxy-2-furyl methyl ketone) (3) and sodium 3-O-hydroxy-2-methyl-4-pyrone hydrate (4) were isolated and characterized from the interaction of isomaltol and maltol with sodium methoxide in boiling benzene (toluene or acetone). Elemental analyses of 3 furnished the formula C₁₂H₁₁NaO₆, and this composition was confirmed by conversion to isomaltol O-benzoyl ester.     

十二烷基磺酸钠对丙烯酰胺－烯丙基磺酸钠共聚物溶液粘度的影响

丙烯酞胺-烯丙基磺酸钠共聚物(PASA)优良的絮凝性能已在前文^[1]中报道.本文主要考察阴离子表面活性剂R₁₂SO₃Na对其溶液粘度的影响,并与PAM做了对照.     

四硫代碳酸钠的合成及其生物活性

以元水Na2S,CS2和S为原料制备了四硫代碳酸钠。探讨了其物理、化学性质及生物活性。