过氧化钠能否氧化氯化铵

从理论和实验2个方面探究了过氧化钠和氯化铵加热的反应, 得出过氧化钠不能氧化氯化钠但可以氧化浓盐酸的结论, 并对反应机理提出了假设。     

碱熔-电感耦合等离子体原子发射光谱法（ICP-OES）测定高碳高硅钢中的硅含量

研究了过氧化钠碱熔-ICP-OES法测定高碳高硅钢样品中的硅含量分析方法。样品经过氧化钠熔融和盐酸浸取后,选择了合适的分析谱线,以信号的稳定性为原则,优化了仪器最佳测定参数,实现了电感耦合等离子体原子发射光谱法对高碳高硅钢中硅含量的测定。通过实验探讨了钠离子、钢中基体元素铁等对硅含量测定干扰情况,测定结果的相对标准偏差不大于2%(n=6)。     

氟硅酸钾容量法测定岩石中的二氧化硅

应用容量法测定岩石中的二氧化硅是比较普遍的,但是,在分析质量上还不够稳定。因为用氢氧化钾与过氧化钠在银(镍)坩埚中熔融矿样易发生喷溅,熔融物常“爬”出坩埚外部,易造成损失。某些矿样,如角闪斜长辉石岩,用氢氧化钾与过氧化钠熔融制成盐酸溶液后,常析出硅酸,使容量法测硅产生严重误差。用过氧化钠-碳酸钠,在银坩埚中熔融,不仅矿样不会损失,而且熔融物制成盐酸溶液后,也不易析出硅酸,保证了容量法测定硅的质量。利用上述熔矿方法,对岩石系统分析也是方便的,它能迅速分解所有矿样,而带进溶液中的杂质却不多。因此利用测硅的溶液,以原子吸收法、比色法及容量法进行铁、锰、钙、镁、铬、镍、铝及钛等元素测定,而不     

读者园地

问:常用无机酸浓度有什么表示方法?答:为使浓度的表述能符合国际单位制的原则和要求,特作如下建议:1.对实验室常用的浓盐酸、浓硝酸、浓硫酸等,应按规定用密度表示,例如浓盐酸应写作盐酸(ρ/1.19 g·mL-1);浓硝酸应写作硝酸(ρ/1.42 g·mL-1);浓硫酸应写作硫酸(ρ/1.84 g·mL-1)。有人将浓盐酸写作“36%V/V”,这种表述不准确,密度为1.19 g·mL-1的盐酸的质量分数为38%,而不是%(V/V)。已明文规定不再使用“%(V/V)”或%(m/m)的表示方法。2.用浓酸配制成稀酸的浓度表示方法有两种,①用浓酸与水的体积比;②用“B的物质的量浓度”表示。例如…     

硫氰酸盐分光光度法测定钨方法的改进

用过氧化钠熔样,在硫酸(1.4mol/L)+盐酸(1.7mol/L)介质中用硫氰酸盐分光光度法测定钨矿石中钨的含量,并对各试剂用量进行了探讨。减少了传统方法中的高浓度盐酸对环境和操作人员造成极大的伤害,测定结果与传统方法的测定结果相吻合。方法用于钨矿石中钨的测定,相对标准偏差为1.2%~8.8%,线性范围为0~18μg/mL,加标回收率为98.89%~100.97%。     

氢氯混合气见光反应条件的探析

用稀硫酸（1：5）和锌粒在小型启普发生器制氢气。若用盐酸,则会使氢气中混有氯化氢气体和盐酸酸雾。制氯气则采用高锰酸钾和浓盐酸。若用二氧化锰和浓盐酸,反应必须加热,若温度高于90℃时,氯化氢可挥发出来。     

过氧化钠与二氧化碳反应的实验——高一化学的补充实验

在一小团脱脂棉(药用棉花即可)上,放一药匙过氧化钠,并将其包起来放在石棉网上,用一支玻璃管,对着过氧化钠用嘴吹气。棉花即剧烈姗烧,且全部姗宪,生成白色固体(碳酸钠);再点燃一团不放过氧化钠的棉花,进行比较,足以说明过氧化钠与二氧化碳反应放出了载气,且为放热反应。     

碱熔-电感耦合等离子体发射光谱法(ICP-OES)测定高碳高硅钢中的硅含量

研究了过氧化钠碱熔-电感耦合等离子体发射光谱法(ICP-OES)测定高碳高硅钢样品中的硅含量分析方法。样品经过氧化钠熔融和盐酸浸取后,以信号的稳定性为原则,优化了仪器最佳测定参数,选择了合适的分析谱线,实现了电感耦合等离子体发射光谱法对高碳高硅钢中硅含量的测定。通过实验探讨了钠离子、钢中基体元素铁等对硅含量测定干扰情况,测定结果的相对标准偏差不大于2%(n=6)。     

过氧化钠是呈白色还是淡黄色

高中化学教材认为过氧化钠是淡黄色固体,这是一种旧观点。笔者认为过氧化钠是白色固体。钠在空气中燃烧的产物是白色的Na2O、Na2O2和淡黄色的NaO2组成的混合物;钠在空气中燃烧的产物颜色主要是由NaO2的存在引起的,过氧化钠并不是淡黄色物质。所以,应该恢复过氧化钠是白色固体的真相,不能再以讹传讹了。     

“超浓盐酸”介质中钯微乳萃取行为

采用多种分子谱学的表征手段, 研究了萃钯有机相中由于酸的共萃导致溶液微观聚集态结构的变化. 研究结果表明, 与高酸度盐酸水溶液平衡后的TBP载钯有机相微乳水团中形成了浓度远大于常规饱和浓盐酸的“超浓盐酸”; 微乳水团内H+和Cl-的大量聚集增浓对Pd离子的络合配位状态产生影响, H+参与了Pd离子配位状态的转变; 有机相“超浓盐酸”形成后, 使得微乳水团中大量存在的H+有可能参与调控水团中各种HmPdClnz+络合离子配位状态的相对含量. 被H+活化的TBP表面活性剂与钯离子的各种配位状态的匹配程度最终决定了钯的萃取行为.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.