Reactions of Hydroxyazolidines with π-Donor Heterocycles. 3. Reaction of 1-Acetyl-5-hydroxypyrazolidines with Oxindoles

The reaction of oxindoles with 5-hydroxypyrazolidines on the surface of potassium fluoride-modified alumina leads to 3-(5-pyrazolidinyl)oxindoles. The structure of these products was studied.     

四元体系KCl-ZnCl2-HCl(～10.61%)-H2O(298.15K)的相平衡及其固相化合物

０引言研究发现，卤化物KX与ZnX２组成的复盐化合物是一种良好的激光基质材料犤１犦，在掺杂了稀土离子的这些化合物中已经实现了低温或室温下的激光输出犤２，３犦。在卤化物中，氯化物的发光强度又大于氟化物犤４犦。因此，我们以KCl与ZnCl２为研究对象，通过盐酸溶液中的相化学反应来了解它们之间可能形成新化合物的种类和溶液中的反应行为。本文对KCl与ZnCl２在２５℃１１％的盐酸－水四元体系中的相平衡关系进行了研究，并从体系中发现并得到了未见文献报道的５∶４型新化合物５KCl·４ZnCl２·３H２O。１实验部分１．１药品及…     

Bis-substituted benzo-15-crown-5 ethers as ion carriers in potassium ion-selective electrodes

Lipophilic bis-substituted ester and ether derivatives of benzo-15-crown-5 have been synthesised. The correlation between the structure and potentiometric ion-selectivity has been studied in PVC membrane ion-selective electrodes. An ion-selective potassium sensitive electrode based on 4,5-bis (biphenyloxymethyl)benzo-15-crown-5 exhibited the best electrode properties. The detection limit was loga _K = -5.4; logK _K,Na ^ppot = -3.5. The effect of the lipophilicity of neutral carriers upon electrode performance has been also discussed.     

不同介质凝胶体系中草酸钙结晶的研究

研究了五种不同介质（水、氯化钠、合成尿、正常人尿液和尿石患者尿液）的凝胶体系中草酸钙（CaC2O4）晶体的生长,及各种体系中防石药物柠檬酸钾（K3cit）对CaC2O4生长的影响.没有加K3cit时,CaC2O4晶体以一水草酸钙（calcium oxalate monohydrate, COM）为主要物相,但在氯化钠和合成尿的凝胶体系中同时出现了二水草酸钙（calcium oxalate dihydrate, COD）和三水草酸钙（calcium oxalate trihydrate, COT）,肾结石患者尿液中出现COD,而正常人尿液中没有COD和COT生成.加入K3cit后,水、氯化钠和合成尿介质的凝胶体系中,COT的含量显著增加,患者尿液中产生大量COD,而正常人尿液中出现了少量的COD和极个别的COT.COT的增加与低温、体系中高的离子强度及金属离子等因素有关.K3cit具有诱导COD和COT的生成、减小COM晶体比表面积的作用,从而有利于防治草酸钙结石的形成.     

Rapid—In—situ Determination of Chromium （VI） in Water Using Modified Diphenylcarbazine with Citrate

In recent years, the determination of Cr (VI) has attracted great attention because of its toxicity to human, plants and animals1-5. Usually, in the industrial waste water, the concentration of Cr (VI) is relatively high and should be determined frequently. So, an accurate, quick, and convenient method for the measurement of Cr (VI) in environmental water, as well as in river, lake, sea and tap water, is of great importance. The method for determination of Cr (VI) by diphenylcarbazine …     

恒电流库仑法测定基准试剂三氧化二砷的含量

用恒电流库仑法测定基准试剂三氧化二砷的含量，以恒电流通过含有碘化钾，基准试剂三氧化二砷试样的弱碱性水溶液，利用工作电极铂阳极上电生滴定剂I2与亚砷酸盐定量反应，以死停终点法确定滴定终点，测量出电解电流和电解时间，根据法拉第电解定律并利用EXCEL计算出基准试剂三氧化二砷的含量。方法的回收率为100％。     

Easy saponification by metal silanolates: application in SPPS and in (S)-5-hydroxynorvaline preparation

Alkali metal trimethylsilanolates, TMSO⁻, M⁺, has been used for efficient conversion of methyl esters into their corresponding anhydrous acid salts under mild non-aqueous conditions. This strategy has been applied to SPPS for the preparation of neurotoxin cyclic analogues and in (S)-5-hydroxynorvaline synthesis.     

Hydration of complexes of 18-crown-6 with potassium nitrate or potassium picrate in the polymer phase

Adsorption of water vapor by granular polymer based on dibenzo-18-crown-6 and containing potassium nitrate or potassium picrate in the polymer phase was studied by the isopiestic method at 298 K. The adsorption of water vapor is described by isotherms corresponding (according to BDDT classification) to polymolecular absorption with a high adsorptive potential. In terms of the Aranovich model of polymolecular absorption, the monolayer capacity and differential heat of adsorption were calculated, and the stoichiometry of hydration of the potassium nitrate and potassium picrate complexes with immobilized crown ether was estimated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1940–1942, October, 1998.     

Thermodynamics of multicomponent electrolyte solutions: Aqueous mixtures of two salts from among NaCl,KCl, NaH2PO4, and KH2PO4 at 25° C

Five of the six possible aqueous two-salt mixtures from among NaCl, KCl, NaH₂PO₄,and KH₂PO₄ have been studied by the isopiestic method at 25°C. The sixth mixture, NaCl–KCl, has been studied previously. The deviations from ideal mixing behavior are described by a series of coefficients which were found by regression analysis. The coefficients were used to calculate the excess Gibbs energies of mixing for equal ionic strength fractions of each salt and the trace activity coefficient of each salt at an ionic strength of 2 mode-kg^–1. The cross-square mixing rule is obeyed within experimental uncertainty for the excess Gibbs energies of mixing.