Die beeinflussung des o/p-Verhältnisses bei azokupplungen mit 1-Naphthylamin in nichtwäßrigen medien

The azo coupling reaction of 1-naphthylamine with diazonium ions under normal conditions in aqueous media occurs predominantly in the 4-position. A study has been made showing how the o/p ratio of this reaction can be influenced in non-aqueous media. It has been found that diazonium ions react with 1-naphthy lamine in solvents with extremely low donor but medium acceptor properties, such as 1,2-dichloroethane and dichloromethane, with higher yields in the 2-position than is the case in solvents with relative high basicity, and also in solvents with both low donor and acceptor numbers, such as carbon tetrachloride. By the addition of carboxylic acids with pK_a values ⩽ 2, such as dichloro- and trichloro-acetic acid, to the solvents with extremely low basicity, the o/p ratio could be clearly increased. Under these conditions, various substituted benzenediazonium tetrafluorborates react with yields of about 90% in the o-position. It has been found that the intermediate formation of 1-naphthylammonium carboxylates plays a decisive role in the surprisingly high selectivity of azo coupling at the 2-position. The reaction proceeds in a similar manner with 1-naphthylammonium dihydrogenphosphate and toluene sulfonate. but not however with the 1-naphthylammonium chloride.     

SYNERGISTIC EXTRACTION OF EUROPIUM(III) WITH BENZOIC ACID AND THENOYLTRIFLUOROACETONE

ABSTRACT

The solvent extraction of europium(III) into solutions of thenoyltrifluoroacetone and benzoic acid in cyclohexane, carbon tetrachloride, benzene, chloroform, pentachloroethane, and tetrachloroethane has been measured at 25°C. It has been found that the extracted species involve two types of adducts, EuA₃· HB and EuA₃· 2HB where A denotes the TTA anion and HB the benzoic acid monomer. The magnitude of the adduct formation constants in different solvents has been correlated with the dimerization constants of benzoic acid in the solvents.     

DYNAMIC ANALYSIS OF SORPTION OF VOLATILE ORGANIC COMPOUNDS IN WATER

Chlorinated and brominated volatile organic compounds are among the groundwater pollutants creating major environmental problems. In this study, dynamic behavior of certain volatile organic compounds in water was investigated by using a novel moment technique. Adsorption equilibrium constant and the penetration length of tracers were evaluated by the first absolute and the second central moment expressions derived for a pulse-response system. In order to obtain adsorption equilibrium constant and penetration length, pulse-response experiments were carried out with different tracers in a one-sided adsorption cell at 30°C. The adsorption equilibrium constants at the gas-water interface were calculated for 1,2-dichloroethane, 1,1,1-trichloroethane, and carbon tetrachloride. This study showed that the adsorption equilibrium constant and the penetration length values could be successfully evaluated using the one-sided adsorption cell moment technique. The adsorption equilibrium constant for 1,2-dichloroethane, 1,1,1-trichloroethane, and carbon tetrachloride were found to be 0.30, 0.49, and 0.54 cm³/cm², respectively.     

Collaborative test of determination of iodine value in fish oils. 2. Carbon tetrachloride or cyclohexane/acetic acid as solvents

Nine laboratories participated in a collaborative test to determine the iodine value (IV) of eight samples of fish oil (four with IV<150; four with IV>150) with either carbon tetrachloride (AOCS Official Method Cd 1–25) or cyclohexane/acetic acid (AOCS Recommended Practice Cd 1d-92) as solvent and 1 h of reaction time. Laboratories received coded duplicate samples (hidden duplicates) and carried out duplicate determinations on each oil by each method (open duplicates). Replacing carbon tetrachloride with cyclohexane/acetic acid resulted in similar mean values for both low- and high-IV oils and similar estimates of repeatability and reproducibility. The repeatability standard deviation (s _r ), based on hidden duplicates, with carbon tetrachloride and cyclohexane/acetic acid were 1.71 and 1.55, respectively. The corresponding reproducibility standard deviations were 1.81 and 1.98.     

Electrochemical preparation and characterization of poly(1-amino-9,10-anthraquinone) films

Poly(1-amino-9,10-anthraquinone), PAAQ, films were prepared by electrochemical oxidation of the monomer, AAQ, in acetonitrile using LiClO₄ as supporting electrolyte. The influence of scan repetition, scan rate and monomer concentration on the formation of polymer film was studied. The electrochemical behavior of the formed polymer films was investigated in both non-aqueous and aqueous media. The prepared films were found to be more stable in organic solvents than in aqueous solutions. The investigated organic solvents are methanol, ethanol, acetone, carbon tetrachloride, benzene, and chloroform. The polymer film shows electrochemical response in both non-aqueous and aqueous media. In non-aqueous solutions it has a wide potential range of electroactivity (from −1.5 to +1.3 V). In aqueous media the polymer film shows electrochemical response in the potential range between −0.3 and +1.3 V only. The presence of quinone units suggests potential applications in diverse areas such as electrocatalytic processes and lithium ion batteries.     

溶剂对SBS形态结构的影响

本文用ＴＥＭ和ＴＢＡ研究了不同的成膜溶剂：甲苯、四氯化碳和环己烷对ＳＢＳ形态结构的影响．认为ＳＢＳ的基本形态结构是两相分离的，聚丁二烯相的连续程度按甲苯＜四氯化碳＜环己烷的顺序增强，并证实了界面层的存在，在此基础上提出了ＳＢＳ的结构模型．     

糠醛产品萃取分离的研究

采用溶剂萃取法分离和精制改良硫酸法甲稻草、麦杆等制取糖醛、，比较了不同有机溶剂的萃取效果和物性，试验结果表明，糖醛的分配系数顺序为：氯仿〉１，２－二氯乙烷〉三氯乙烯〉乙酸乙酯〉四氯化碳。选择了３级错流萃取流程和设备．     

Collaborative test of determination of iodine value in fish oils. 1. Reaction time and carbon tetrachloride or cyclohexane as solvents

Twenty-two laboratories participated in a collaborative test to determine the iodine value (IV) of eight samples of fish oil (four with IV<150, four with IV>150) with either carbon tetrachloride (AOCS Official Method Cd 1–25) or cyclohexane (AOCS Recommended Practice Cd 1b-87) as solvent and either 1 or 2 h of reaction time. Laboratories received coded duplicate samples (hidden duplicates) and carried out duplicate determinations on each oil by each solvent-time combination (open duplicates). Replacing carbon tetrachloride with cyclohexane resulted in a lower IV (P<0.001). The decrease averaged 1.6 IV units for low-IV oils and 3.8 IV units for high-IV oils; this difference in response of 2.2 IV units between low- and high-IV oils was significant (P<0.001). Increasing the reaction time had a relatively small effect (0.34±0.18). There was no interaction of reaction time with solvent or oil type. Cyclohexane caused emulsions, which made it difficult to titrate residual iodine and thus increased the variability of the determination. The repeatability standard deviations (s _r ), based on hidden duplicates, for 1-h reaction time with carbon tetrachloride and cyclohexane were 2.17 and 3.35, respectively. The corresponding reproducibility standard deviations were 2.73 and 4.53.     

Spectroscopic investigations of the water pool in lecithin reverse micelles

The nature of the water pool formed in the reverse micellar system, lecithin/nonpolar solvent/water, has been investigated by means of near infrared, ultraviolet, fluorescence emission and visible spectroscopic techniques. The three nonpolar solvents chosen in this study were benzene, carbon tetrachloride and cyclohexane. Near infrared spectroscopic studies revealed that the amount of water present in the bulk organic phase is negligible at all water concentrations studied in all three solvents. The results of the polarity probe and 8-anilinonaphthalene sulfonic acid (ANSA) fluorescence emission maxima studies indicate that the polarity of the water pool is much lower than that of bulk water. The difference in polarity between the water pool and bulk water decreases with increasing water concentration in benzene and carbon tetrachloride systems. However, in the cyclohexane system, at a water content of 6 moles of water per mole of lecithin, where the system is known to change from isotropic reverse micelle to anisotropic liquid crystalline state, the polarity of the water pool is found to decrease.     

EXTRACTION OF TRIS(MALONATO) CHROMATE(III) BY SOLUTIONS OF ALIQUAT-336 IN VARIOUS ORGANIC SOLVENTS

Abstract

The extraction of tris(raalonato) chromate(III) by solutions of Aliquat-336 in various organic solvents such as n-pentane, n-heptane, cyclohexane, chloroform, carbon tetrachloride, o-xylene,benzene, toluene, nitrobenzene and nitromethane has been studied. The effect of the organic solvent on the extraction is correlated with their solubility parameters by application of the theory of regular solutions. The solubility parameter of the extracted species is reported.     

Characterization of styrene-butadiene copolymers by light scattering

The general theory of Stockmayer and Benoit and their coworkers yields the weight average molecular weight of a binary copolymer and parameters which reflect the heterogeneity of chemical composition of the copolymer, using light scattering data from solutions in at least three solvents with different refractive indices. Although this theory has been applied successfully to block and graft copolymers and to mixtures of homopolymers, it has not seemed to be valid for random copolymers.In this report, molecular weight and heterogeneity parameters of a number of gel-free styrene-butadiene emulsion copolymers were estimated from results of light scattering measurements in toluene, cyclohexane and 1,2-dichloroethane. The calculated heterogeneity parameters contradict expectations from copolymerization theory and appear to be in error. It is suggested that the particular difficulties with statistical copolymers result from a dependence of specific refractive index increment on polymer molecular weight. This dependence varies with different solvents. The effect is illustrated by experimental results for polystyrenes in toluene, cyclohexane and 1,2-dichloroethane. Accurate study of copolymer characteristics requires selection of solvents such that the differences between specific refractive indices of the appropriate homopolymer solutions do not depend strongly on polymer molecular weight in the molecular weight range which corresponds to the sum of homopolymer sequences in the particular copolymers. The apparent inapplicability of the theory to random copolymers appears to be an artifact of the particular systems which were studied.     

Reversible phase transfer of graphene oxide and its use in the synthesis of graphene-based hybrid materials

A phase transfer protocol for graphene oxide (GO) was demonstrated with a long chain alkylamine–dodecylamine (DDA) as phase transfer agent. By this method, GO sheets can be easily transferred from water to various low polar organic solvents such as cyclohexane, petroleum ether, kerosene, toluene, carbon tetrachloride, etc. through forming noncovalent DDA–GO hybrids. The reversible phase transfer of GO between aqueous phase and organic phase was also realized through the formation and destruction of a DDA–GO micelle. It was found that ethanol plays a critical role in the phase transfer process, while other experimental parameters, such as pH value and the concentration of GO, do not have an obvious influence on the transfer efficiency over a wide range. A detailed mechanism for the phase transfer is proposed on the basis of experimental observation. With this phase transfer technique, a simple, efficient, and versatile approach is also developed to synthesize a variety of graphene-based metal and alloy hybrids in low-polar organic solvents.     

Metal‐Free and Copper‐Promoted Single‐Pot Hydrocarboxylation of Cycloalkanes to Carboxylic Acids in Aqueous Medium

A simple and effective method for the transformation, under mild conditions and in aqueous medium, of various cycloalkanes (cyclopentane, cyclohexane, methylcyclohexane, cis‐ and trans‐1,2‐dimethylcyclohexane, cycloheptane, cyclooctane and adamantane) into the corresponding cycloalkanecarboxylic acids bearing one more carbon atom, is achieved. This method is characterized by a single‐pot, low‐temperature hydrocarboxylation reaction of the cycloalkane with carbon monoxide, water and potassium peroxodisulfate in water/acetonitrile medium, proceeding either in the absence or in the presence of a metal promoter. The influence of various reaction parameters, such as type and amount of metal promoter, solvent composition, temperature, time, carbon monoxide pressure, oxidant and cycloalkane, is investigated, leading to an optimization of the cyclohexane and cyclopentane carboxylations. The highest efficiency is observed in the systems promoted by a tetracopper(II) triethanolaminate‐derived complex, which also shows different bond and stereoselectivity parameters (compared to the metal‐free systems) in the carboxylations of methylcyclohexane and stereoisomeric 1,2‐dimethylcyclohexanes. A free radical mechanism is proposed for the carboxylation of cyclohexane as a model substrate, involving the formation of an acyl radical, its oxidation and consequent hydroxylation by water. Relevant features of the present hydrocarboxylation method, besides the operation in aqueous medium, include the exceptional metal‐free and acid‐solvent‐free reaction conditions, a rare hydroxylating role of water, substrate versatility, low temperatures (ca. 50 °C) and a rather high efficiency (up to 72% carboxylic acid yields based on cycloalkane).     

Solubility of acetylene in several polar and non-polar solvents and solvent mixtures

Solubilities of acetylene in pure solvents, hexane, cyclohexane, hexadecane, benzene, carbon disulfide, carbon tetrachloride, methanol, butanol and ethylene glycol, and mixtures, hexane-hexadecane and butanol-ethylene glycol, are reported at atmospheric pressure and temperatures ranging from 0 C to 50 C. Hydrogen bonding (H-bonding) factors expressed by a simplified Margules equation were found useful to correlate the solubilities of gases in the pure solvents as well as the solvent mixtures.     

DILUENT EFFECT ON THE EXTRACTION OF URANIUM(VI) FROM HYDROCHLORIC ACID SOLUTIONS BY TRIOCTYLMETHYLAMMONIUM CHLORIDE

ABSTRACT

The extraction of uranium(VI) from hydrochloric acid solutions by trioctylmethylammonium chloride (TOMAC) has been examined using various diluents such as benzene, chlorobenzene, o-dichlorobenzene, toluene, m-xylene, nitrobenzene, carbon tetrachloride, chloroform and 1,2-dichloroethane. It was found that by assuming a regular solution, the distribution coefficient and the enthalpy change associated with the metal extraction can be expressed in terms of the solubility parameter of TOMAC, diluent and the complex formed in the organic phase and their molar volumes. Additionally an empirical relation holds between distribution coefficient and the viscosity of diluent. Further results for the extraction of divalent manganese, cobalt, copper, zinc and cadmium from hydrochloric acid solutions by TOMAC are investigated in comparison with those of uranium(VI).     

Solvent replacement in the synthesis of persubstituted phosphonitrilic hydroquinone prepolymer materials

A desirable solvent replacement has been effected in the synthesis of persubstituted phosphonitrilic hydroquinone prepolymer materials. The replacement of carbon tetrachloride with cyclohexane has no adverse effect on the composition and quality of the material prepared. The overall yield of the reaction increases from 65 to 70% and the toxicity of the reaction mixture and of the waste generated from the reaction are greatly reduced. The particularly close match of solvent properties between carbon tetrachloride and cyclohexane makes this an excellent solvent replacement. Such changes to less-expensive, less-toxic, and less-environmentally damaging solvents are on the increase. A brief list of some known replacement solvents for use in polymer and coatings applications is presented. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

褐藻糖胶的萃取和反萃

研究了无机盐种类和浓度对N263萃取褐藻糖胶的影响. 结果表明,无机盐浓度是影响褐藻糖胶萃取的最主要因素, 褐藻糖胶的萃取率随盐浓度的增加而迅速降低,在无机盐存在下,增加萃取剂浓度并不能增加对褐藻糖胶的萃取. 用盐水溶液反萃不同条件下萃取的褐藻糖胶,结果表明,反萃率随盐浓度的增加而增加,在相同的氯离子浓度下,钠盐的反萃效率优于钙盐,随有机相中褐藻糖胶浓度的增加, 盐的反萃效率降低. 比较了不同溶剂作为稀释剂对用盐溶液反萃褐藻糖胶的影响,表明CCl4作为稀释剂时盐的反萃效率最低.     

THERMODYNAMIC STUDIES ON THE EXTRACTION OF ZINC(II)FROM HYDROCHLORIC ACID SOLUTIONS BY TRIOCTYLMETHYLAMMONIUM CHLORIDE IN VARIOUS DILUENTS

ABSTRACT

In the extraction of zinc(II) from hydrochloric acid solutions by trioctylmethylammonium chloride in various organic diluents such as benzene, chlorobenzene, o-dichlorobenzene, toluene, m -xylene, nitrobenzene, carbon tetrachloride and 2,2-dichloroethane, the heat change associated with zinc(II) extraction has been examined by calorimetry. In the case of benzene used as diluent, it is confirmed that the heat change detected can be interpretated as the summation over the change in enthalpies for the relevant steps to the extraction of zi(II), taking the change in enthalpy obtained from the temperature-dependence of the distribution coefficient into account. Applying this approach of zinc(II) extraction for other diluents, it is found that the distribution of zinc (II) between aqueous and organic phases can be explained very well by assuming a regular solution.     

手性溶剂萃取分离布洛芬对映体

研究了布洛芬对映体在含有疏水性L-酒石酸酯的1,2-二氯乙烷溶液及甲醇水溶液两相中的萃取分配行为,考察了不同烷基链长的L-酒石酸酯、D-酒石酸酯以及L-酒石酸酯的浓度、有机溶剂的种类和溶解布洛芬的甲醇水溶液浓度对分配系数K和分离因子α的影响。实验表明,L-酒石酸酯与布洛芬Ⅱ对映体形成的复合物稳定性比与布洛芬Ⅰ对映体形成的复合物稳定性要大,而D-酒石酸酯的萃取性能则与此相反,它与布洛芬Ⅰ对映体形成的复合物稳定性比与布洛芬Ⅱ对映体形成的复合物稳定性要大。有机溶剂的萃取性能为醇＞1,2-二氯乙烷＞烷烃,随着溶解布洛芬的甲醇水溶液中甲醇浓度的增大,分配系数K和分离因子α均降低,当甲醇的浓度为10%时,可以得到最佳的K和α。随着L-酒石酸酯浓度的提高,分配系数K和分离因子α先增大后减小,当L-酒石酸酯的浓度约为0.2 mol·L-1时,K和α达到最大值;L-酒石酸酯的碳链长度对分配系数K和分离因子α也有很大的影响。     

Permanent adsorption of organic solvents in graphite oxide and its effect on the thermal exfoliation

The dispersion of graphite oxide (GO) in organic solvents followed by their evaporation at relative high temperature resulted in a strong adsorption of the solvent molecules in the graphitic interlayers as confirmed by ¹³C magic-angle-spinning NMR. Three series of solvents, alcohols (1-methanol, 1-propanol, 1-pentanol, 1-heptanol), aromatics (benzene, toluene, p-xylene, chlorobenzene) and chloride compounds (dichloromethane, chloroform, carbon tetrachloride) were studied to understand the interaction of graphite oxide with solvents. The distribution of basal interlayer spacing changed due to solvent intercalation and this distribution was particularly different for each solvent series. Even though there was on average 1 solvent molecule per 100 carbon atoms of GO, they had a profound effect on the thermal properties of the resulting GO. The exfoliation temperature was drastically reduced by the presence of the solvents due to the increase of the interlayer spacing and the reducing power of the solvent.