Interfacial syntheses of polyphosphonate and polyphosphate esters. I. Effects of alkaline medium

The effects on polymer yield and viscosity in the interfacial condensation of hydroquinone with phenylphosphonic dichloride as a function of the pH of the aqueous medium are reported. Reactions competing with polymer formation are discussed. The beneficial advantages in the use of soluble buffers or bases of limited water solubility to control pH are contrasted with results of conventionally used sodium hydroxide. The results of investigations of other comer pairs for which reaction conditions have not been optimized are also reported; desoxyribose and the diols: thymidine, resorcinol, 2,5-dichlorohydroquinone, 1,3-dihydroxyacetone, 1,4-butanediol, tartaric acid, ethylene glycol, and 2,2-dimethyl-1,3-propanediol are tabulated.     

The use of 2-0xazolidinone as a latent aziridine equivalent. I. A facile method for the preparation of 2-substituted oxazolines

Ring-opening reaction of 2-oxazolidinone with acid chlorides followed by treatment with aqueous sodium hydroxide yields 2-substituted oxazolines.     

Synthesis and reactions of some 4-heteroaryl-3-nitrocoumarins—

By the action of 2-aminothiazole, 2-aminopyridines, and 2-aminopyrimidines, respectively, on 4-chloro-3-nitrocoumarin ( 3 ) the corresponding 4-heteroarylamino-3-nitrocoumarins 5–7 have been isolated in very good yields. Reactions of coumarins 6 and 7 with either aqueous tetrabutylammonium bisulfate/sodium hydroxide in a two phase system or 5% aqueous sodium hydroxide have been studied.     

Difluoromethyltrialkylammonium salts--their expeditious synthesis from chlorodifluoromethane and tertiary amines in the presence of concentrated aqueous sodium hydroxide. The catalytic process

We found that difluorocarbene generated from chlorodifluoromethane with 50% aqueous sodium hydroxide reacts with lipophilic tertiary amines 1a-g giving difluoromethyltrialkylammonium chlorides 2a-g in high yields. Similarly, difluoromethyltrialkylammonium iodides 3h-l, nitrates 4h-k, or isothiocyanates 5i,j were synthesized from hydrophilic tertiary amines 1h-l and the corresponding sodium or potassium salts. The process is catalytic with respect to the base used.     

OXIDATIVE POLYMERIZATION BEHAVIOR OF 2,6-DIMETHYLPHENOL IN AQUEOUS MEDIA WITH POTASSIUM FERRICYANIDE

The effects of potassium ferricyanide,sodium n-dodecyl sulfate,sodium hydroxide and temperature on the molecular weight and the yield of poly(2,6-dimethyl-1,4-phenylene oxide)(PPO) synthesized in an aqueous medium were studied.It was found that oxygen in air had little influence on the oxidative polymerization of 2,6-dimethylphenol(DMP) in the aqueous medium,and potassium ferricyanide was only an oxidant during the oxidative polymerization of DMP.Sodium n-dodecyl sulfate could stabilize polymer particles...     

Etude rheologique de gels mixtes de poly(alcool vinylique) et d'alginate de sodium

Snake-cage hydrogels were prepared by the association of poly(vinyl alcohol) (PVA) and sodium alginate. The aim of this work is to study the viscoelastic properties of PVA networks having different molecular weights and trapping alginates of various mannuronate/guluronate ratios, molecular weights and aqueous concentration. The elastic and viscous moduli, G′ and G″, were found to depend on alginate concentration. With the sodium alginate (mannuronate/guluronate =1.78, M̄w=380 000), the elasticity was observed to be independent of the PVA molecular weight in the 7.5% to 10% (w/w) concentration range. Hydrogels elasticity was found to be sodium alginate nature-dependent only in the case of PVA with M̄w =22 000. Moreover, it seems that the viscoelastic parameters G′ and G″ become increasingly insensitive to the nature of sodium alginate as the molecular weight of PVA increases.     

Synthesis of 2-carboxy-4-methylazetidine. A novel isomeric analog of dl-proline

L-Azetidine-2-carboxylic acid is a naturally occurring azetidine currently used in the synthesis of abnormally high molecular weight polypeptides. The synthesis of 2-carboxy-4-methylazetidine is now reported which is a novel isomeric analog of dl -proline. Reaction of α,β-dibromo carbonyl ester with three molar equivalents of benzylamine yields 1-benzyl-2-carbomethoxy-4-methyl-azetidine. Hydrolysis of the latter compound with barium hydroxide yields 1-benzyl-2-carboxyl-4-methylazetidine which, if subjected to catalytic hydrogenation., yields the title compound in practical yield. The cis configuration is tentatively assigned to the title compound on the basis of previously published arguments.     

胶束介质中的Wittig—Horner反应研究

近年来手性胶束及混合胶束的出现,使得胶束在模拟酶研究方面取得了长足的进展。胶束作为酶的一个简单模型,可催化多种复杂有机反应,已有的胶束催化有机反应大多数与生化反应有关,如酯的水解反应等,胶束催化碳负离子反应的研究却很少,非离子型胶束催化的碳负离子反应就更少,本文报导用聚乙二醇类表面活性剂形成的胶束来     

Three-compartment bipolar membrane electrodialysis for splitting of sodium formate into formic acid and sodium hydroxide: Role of diffusion of molecular acid

Bipolar membrane electrodialysis is used in a three-compartment configuration to regenerate formic acid and sodium hydroxide from sodium formate. A previous study showed that the diffusion of molecular formic acid induces the loss of acid current efficiency. The present study shows the following results: the diffusion of molecular formic acid through the bipolar membrane explains quantitatively the presence of sodium formate in the sodium hydroxide solution. The loss of acid current efficiency is only due to diffusion of molecular acid through both anion-exchange and bipolar membranes. The sodium hydroxide current efficiency is determined by acid diffusion through the bipolar membrane and OH⁻ leakage through the cation-exchange membrane. The flux of acid diffusion through the membranes is proportional to acid concentration and depends on sodium hydroxide concentration for bipolar membrane and on sodium formate concentration for anion-exchange membrane. The flux rates vary with temperature.     

An efficient synthesis of pyrazole chalcones under solvent free conditions at room temperature

An easy,safe,solvent free and effective method for the synthesis of pyrazole-substituted chalcones has been achieved by grinding pyrazole aldehydes and acetophenones in the presence of activated barium hydroxide(C-200) in high yield within short span of time.All reactions were carried out just by grinding the two reactants in the presence of activated barium hydroxide(C-200). Results are also compared with sodium hydroxide and potassium hydroxide.     

Coprecipitation of uranium and thorium with barium sulfate

The coprecipitation behaviour of uranium or thorium with barium sulfate is investigated from the variation of yields with uranium or thorium concentration, acid and acidity, and amount of sodium and/or potassium sulfate. Uranium or thorium in quantities less than 1.5 mg is quantitatively coprecipitated with barium (5.9 mg) sulfate when using an optimum conditions. The chemical form of uranium in barium sulfate precipitates is discussed by determination of mole ratio of potassium to uranium.     

Dehydrochlorination of vinylidene chloride-vinyl chloride copolymer by aqueous sodium or potassium hydroxide solutions under two-phase conditions

The reaction of solid copolymer of vinylidene chloride and vinyl chloride with aqueous sodium or potassium hydroxide solutions in the presence of quaternary ammonium or phosphonium salts as phase transfer catalysts gave dehydrochlorinated products with chlorine-substituted polyene structure. Among the catalysts used tetrapropylammonium bromide was the best and potassium hydroxide was more active than sodium hydroxide. The activity of quaternary ammonium salts was discussed in terms of hydrophile–lipophile balance. The effects of temperature and the concentration of the bases and catalysts were investigated to obtain the optimum reaction condition. Treatment of the polymer films and solutions in tetrahydrofuran with aqueous bases under two-phase conditions also produced dehydrochlorinated films and powders.     

Dehydrochlorination of poly(vinyl chloride) by aqueous sodium hydroxide solution under two-phase conditions

The reaction of poly(vinyl chloride) powder with aqueous sodium hydroxide solution in the presence of quaternary ammonium or phosphonium halides yielded dehydrochlorinated products of conjugated polyene structure. The reaction was discussed in terms of a phase transfer catalytic mechanism between aqueous and polymer phases. Among the catalysts used tetrabutylammonium bromide was the best. To obtain the optimum conditions the effects of reaction temperature, the concentration of NaOH and the catalyst, and the molecular weight of poly(vinyl chloride) were investigated. Treatment of PVC films and solutions in tetrahydrofuran with aqueous NaOH solutions under two-phase conditions also produced dehydrochlorinated films and powders.     

超声辐射和相转移催化下肟苄醚的合成

在超声辐射和苄基十四烷基二甲基氯化铵作用下, 肟和苄基溴在NaOH水溶液中于室温反应30～60 min, 肟苄基醚的收率60%～96%, 反应时间短, 收率高, 对环境友好.     

Simple synthesis of functionalized 7-aza-2H-chromenes from pyridoxal and nitroalkenes in aqueous medium

A reaction of 1-nitro-3,3,3-trichloro(trifluoro)propenes and β-nitrostyrene with pyridoxal hydrochloride in the presence of sodium hydroxide in aqueous medium gives good yields of new derivatives of 7-aza-2H-chromene system.     

Potentiometric titration of hydroxide,aluminate and carbonate in sodium aluminate solutions

An automated potentiometric titration of hydroxide, aluminate and carbonate in sodium aluminate solutions is described. The addition of barium chloride before titration with hydrochloric acid enables the three components to be determined in one run, involving neutralization of hydroxide, protonation of aluminate and dissolution of barium carbonate. The accuracy and precision of the method are satisfactory for a rapid method used for control of aluminum oxide production.     

氢氧化钡沉淀–碘量法对高锰酸钾和锰酸钾共存时的分别测定

采用氢氧化钡沉淀–碘量法对高锰酸钾和锰酸钾共存时的含量分别进行测定。向电解液中加入过量的饱和氢氧化钡溶液,利用锰酸钡和高锰酸钡溶度积的不同进行分离,再用碘量法分别对高锰酸钾和锰酸钾进行测定。结果表明,高锰酸钾和锰酸钾的检出限分别为0.061,0.077 g/L,测定结果的相对标准偏差分别为0.57%和0.72%(n=4),高锰酸钾的加标回收率为94.12%~95.85%。t检验结果表明,氢氧化钡沉淀–碘量法与传统方法对高锰酸钾和锰酸钾的测定结果无显著性差异。该法避免了亚铅酸钠和铬盐的毒性及滴定终点颜色不易判断等缺点,适合于高锰酸钾工业生产中主要成分的快速检测。     

Carbon Dioxide Measurements with and without Barium Peroxide in Electrolytic Studies with and without a Supporting Electrolyte

Abstract

This research deals with the quantitative formation of carbon dioxide in electrolytic oxidation reactions. The electrolytic reactions were run with barium peroxide to generate the superoxide anion at the anode. With the organic compounds used in these electrolytic studies we needed to develop a method where we could determine the amount of carbon dioxide liberated from these compounds with the superoxide anion. This method degasses an acidified solution with dry nitrogen, which carries the carbon dioxide to a standard solution of sodium hydroxide. Titration of the sodium hydroxide solution with standardized hydrochloric acid revealed the amount of carbon dioxide formed in the reaction after precipitation of the carbonate ions with barium chloride. Blank runs with the apparatus using anhydrous sodium carbonate produced 99% plus results of recovered carbon dioxide from the sodium carbonate.     

超声辐射下水溶液中合成2,3-环氧-1,3-二芳基丙酮

在氢氧化钠水溶液中, 通过氯代苯乙酮和芳香醛进行Darzens缩合反应, 在超声辐射下, 合成了系列2,3-环氧- 1,3-二芳基丙酮; 应用超声和相转移催化剂联用的方法进行改进, 取得良好效果. 与传统的合成方法比较, 该方法反应条件温和、溶剂无毒、反应时间短和产率高.     

Volatility of radioactive iodine under gamma irradiation: effects of H2O2 and NaOH on the decomposition rate of volatile molecular iodine dissolved in aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - The decomposition of molecular iodine by hydrogen peroxide and sodium hydroxide was kinetically studied in aqueous solutions at ambient...