Stability Constants of Some Univalent Cation Complexes of 2,3-Naphtho-15-crown-5 in Nitrobenzene Saturated with Water

The extraction of micro amounts of cesium by nitrobenzene solutions of sodium, potassium and rubidium dicarbollylcobaltates (M⁺B⁻;M⁺=Na⁺,K⁺,Rb⁺) has been investigated in the presence of 2,3-naphtho-15-crown-5 (N15C5, L). The equilibrium data were explained by assuming that ML⁺ and ML₂⁺ complexes (M⁺=Na⁺,K⁺,Rb⁺, Cs⁺; L=N15C5) were present in the organic phase. The stability constants of the complex species ML⁺ and ML₂⁺ have been determined in nitrobenzene saturated with water. It was found that the stability of the complex cation ML⁺ (where M⁺=Na⁺,K⁺,Rb⁺, Cs⁺; L=N15C5) in water-saturated nitrobenzene solutions increases along the series Cs⁺<Rb⁺<K⁺<Na⁺, whereas that of the species ML₂⁺ in the same medium increases in the order Cs⁺<Rb⁺<Na⁺<K⁺.     

Solvent Modification in Ion-Pair Extraction: Effect on Sodium Nitrate Transport in Nitrobenzene Using a Crown Ether

A comparative quantitative analysis of the effect of solventmodifiers on the ion-pair extraction of an inorganic salt by a crown ether was conducted with the aim of advancing the understanding of transport of highly hydrophilic metal ions from aqueous salt solutions. Two classes of solvent modifiers that possess electron-pair donor (EPD) or hydrogen-bond donor (HBD) groups were investigated. The equilibrium constants corresponding to the extraction of sodium nitrate into nitrobenzene (NB) employing model neutral host cis-syn-cis-dicyclohexano-18-crown-6 (compound 1) with and without solvent modifier were determined using the SXLSQI computer model. For a series of EPD modifiers—including tri-n-butyl- and tri-phenylphosphate, tri-n-butyl- and tri-phenylphosphine oxide, N,N-di-n-butyl- and N,N-di-phenylacetamide—the enhancement of the NaNO₃ extraction by compound 1 was found to be dependent on the hydrogen-bond acceptance ability of the modifier as quantified by the β solvatochromic parameter. A HBD modifier 3,5-di-t-butylphenol (compound 8), which forms strong hydrogen bonds with nitrate anion in NB, exhibited even greater enhancement of the NaNO₃ extraction by compound 1. The determined extraction constants were correlated with the β- or α-solvatochromic parameters of the solvent modifiers and linear trends were observed. Hydrogen bond interaction between compound 8 and nitrate anion in the presence of the sodium-loaded crown ether in the extraction phaseswas studied by vibrational spectroscopy.     

Solvent Effect upon Ion-pair Extraction of Different Sodium Dyes Using Some Crown Ethers

Liquid-liquid extractive-spectrophotometric studies of sodium ion complexes of 18-crown-6(18C6), dibenzo-18-crown-6(DB18C6), 15-crown-5(15C5), and 12-crown-4(12C4) and anionic dyes [4-(2-pyridylazo)-resorcinol monosodium salt monohydrate (PAR), Eriochrom Black T (EBT), and methyl orange (MOR)] and sodium picrate (PICRAT) as the counter ion are described. The overall extraction equilibrium constants for the 1 : 1 complexes of the above crown ethers with sodium dyes between different organic solvents and water have been determined at 25deg;C. They were conducted in various solvent-water systems maintaining an identical initial cation concentration in water, [M0+]w, and macrocyclic ligand concentration in the organic phase, [L0]org}, so that in all extractions [M0+]w : [L0]org ratios were 1 : 1, 1 : 10, 1 : 20, 1 : 50, and 1 : 62.5. An ion association complex formed between the sodium-crown ether complex ion and a dye anion was extracted into the organic solvent, and then the dye concentration of the separated aqueous phase was measured with an ultraviolet-visible spectrophotometer. PAR was the best associated dye with all crown ethers sodium-dyes and the extracted dye occurs as the ion-pair complex. Methylene chloride was found to be better than other extractive solvents used in this study.     

液液萃取-气相色谱法测定地表水中10种硝基苯类化合物

将水样(200mL)用正己烷(10mL)萃取,所得萃取液经无水硫酸钠干燥后供气相色谱分析。用DB-1701色谱柱,温度在110℃～210℃区间采用程序升温方式进行分离,用电子捕获检测器测定。10种硝基苯类化合物的峰面积与对应的质量浓度在一定范围内呈线性关系,检出限在0.10～2.5μg.L-1之间。用标准加入法测得10种硝基苯类化合物的回收率在86.4%～96.2%之间,测定值的相对标准偏差(n=7)均小于5%。     

Synergistic Effect of Mandarin Peels and Hesperidin with Sodium Nitrite against Some Food Pathogen Microbes

Food preservatives such as NaNO₂, which are widely used in human food products, undoubtedly affect, to some extent, human organs and health. For this reason, there is a need to reduce the hazards of these chemical preservatives, by replacing them with safe natural bio-preservatives, or adding them to synthetic ones, which provides synergistic and additive effects. The Citrus genus provides a rich source of such bio-preservatives, in addition to the availability of the genus and the low price of citrus fruit crops. In this study, we identify the most abundant flavonoids in citrus fruits (hesperidin) from the polar extract of mandarin peels (agro-waste) by using spectroscopic techniques, as well as limonene from the non-polar portion using GC techniques. Then, we explore the synergistic and additive effects of hesperidin from total mandarin extract with widely used NaNO₂ to create a chemical preservative in food products. The results are promising and show a significant synergistic and additive activity. The combination of mandarin peel extract with NaNO₂ had synergistic antibacterial activity against B. cereus, Staph. aureus, E. coli, and P. aeruginosa, while hesperidin showed a synergistic effect against B. cereus and P. aeruginosa and an additive effect against Staph. aureus and E. coli. These results refer to the ability of reducing the concentration of NaNO₂ and replacing it with a safe natural bio-preservative such as hesperidin from total mandarin extract. Moreover, this led to gaining benefits from their biological and nutritive values.     

Extraction of Alkylphenols and Nonylphenol Mono- and Diethoxylates from Water Using Magnetically Modified Adsorbents

An LC-DAD-ESI-MS⁽²⁾ method was developed for simultaneous analysis of major chemical constituents in Shexiang Baoxin Pill (SBP), an important multiherbal formula in traditional Chinese medicine widely used for treating cardiovascular diseases. The chromatographic separation was performed on a Symmetry C₁₈ column (5 μm, 250 × 4.6 mm), whilst water with 0.5% formic acid and acetonitrile were used as mobile phase. On the basis of the characteristic UV absorption profile, the information of molecular weight and structure provided by ESI-MS⁽²⁾, 57 constituents from moschus, radix rhizoma ginseng, calculus bovis, cortex cinnamomi, styrax and venenum bufonis, were detected and 47 of them were identified in this study. The method can be the basis for the quality control of SBP.     

Extraction of Arsenic(V) from Water Using Emulsion Liquid Membrane

In this article, the extraction of arsenic(V) from water by means of emulsion liquid membrane is investigated. The influence of operating factors such as stirring speed, concentration of sulfuric acid in the external aqueous phase, concentration of sodium sulfate in internal stripping phase, and concentration of carrier in the membrane phase on the extraction efficiency are investigated and their optimum values, which provide the maximum recovery of arsenic, are determined. Taguchi experimental design is used in order to reduce the number of experiments. The optimum amounts for the extraction of arsenic from water, based on the results, are: stirring speed, 500 rpm; concentration of sulfuric acid in the feed, 1.5 g mol/lit; concentration of reagent in internal phase, 1.5 g mol/lit; and concentration of carrier in 3 ml kerosene which is added to the membrane phase, 0.1 g mol/lit.     

Functional Features of Alginates Recovered from Himanthalia elongata Using Subcritical Water Extraction

Subcritical water extraction of Himanthalia elongata and the subsequent acetone fractionation to precipitate crude fucoidans generated a liquid phase which was used to recover alginates with a wide range of viscoelastic features and other soluble extracts with potential biological activities. The precipitated alginate was converted to sodium alginate using an environmentally friendly treatment before being characterized by Fourier transform infrared attenuated total reflectance, nuclear magnetic resonance, high performance size exclusion chromatography and rheological measurements. The cell viability of three human cell lines (A549, HCT-116, T98G) in the presence of the extracts obtained before and after acetone fractionation was assessed. Fractionation with different acetone volumes showed a slight effect in the behavior of the different tested cell lines. Results also indicated a notable effect of the processing conditions on the block structure and molar mass of the extracted biopolymer, with the subsequent impact on the rheological properties of the corresponding gelled matrices.     

Generation of Chloropolyfluoromethylene-1-indanyl Cations and Their Isomerization into Chloropolyfluoromethylindenyl Cations

Chlorooctafluoro-3-methylene-1-indanyl, 3-(chlorofluoromethylene)heptafluoro-1-indanyl, and 2- and 3-(dichloromethylene)heptafluoro-1-indanyl cations were generated from the corresponding dihalomethyleneindans in the system SbF₅-SO₂ClF. Isomerization of these cations yields thermodynamically more stable polyfluoromethylindenyl cations with chlorine atoms in the five-membered ring.     

液液萃取-GC-MS法测定水中硝基苯质量控制指标研究

采用液液萃取–气相色谱–质谱法测定水中硝基苯,通过统计全国多家实验室的测定数据,对平行样测定结果相对偏差、空白加标回收率、样品加标回收率、空白加标回收率相对偏差及样品加标回收率相对偏差5个质控指标进行分析,得出质控指标评价标准。在概率P,γ均为0.90时,平行样测定结果允许最大相对偏差应控制在11.0%;当空白加标浓度为0.2～30μg/L时,回收率控制范围为59%～113%;当样品未检出、加标浓度在0.25～50μg/L时,样品加标回收率控制范围为56%～110%;空白加标、样品加标回收率最大相对偏差应分别控制在10.0%和11.1%。在概率P和γ均为0.95时,平行样测定结果允许最大相对偏差应控制在13.5%;当空白加标浓度为0.2～30μg/L时,回收率的控制范围为50%～122%;当样品未检出、加标浓度在0.25～50μg/L时,样品加标回收率控制范围为49%～117%;空白加标、样品加标回收率最大相对偏差应分别控制在12.6%和14.6%。     

磁性分散固相萃取气相色谱法测定地表水中硝基苯类

建立了一种磁性分散固相萃取气相色谱法快速测定地表水中硝基苯类化合物的分析方法,并优化了磁性萃取材料的用量、萃取的时间、解吸溶剂的选择、盐效应等试验影响因素.试验结果表明,硝基苯类化合物的检出限为0.000 4~0.007 mg/L,回收率为84.0%~97.6%,相对标准偏差为3.4%~5.3%.方法具有适用性广、溶剂用量少和操作简便等特点,能很好的测定地表水中的硝基苯类化合物.     

十二烷基硫酸钠与甜菜碱在气液和油水界面的复配协同作用研究

研究了十二烷基硫酸钠（SDS）和甜菜碱（Betaine）以及复配体系在油水界面和气液界面的排布行为,探讨了温度、无机盐和复配比例对表面活性剂界面活性和泡沫稳定性的影响,重点探讨了多价无机阳离子对表面活性剂界面吸附行为和复配协同加合增效作用的影响,得到了海水为介质条件下两方面性能均较好的体系,取得的认识为高盐条件下低张力泡沫驱油体系的设计与应用提供理论依据和指导.     

利用乙醇重整制氢进行硝基苯原位液相加氢合成苯胺

 利用乙醇液相催化重整制得的氢直接进行硝基苯原位液相加氢合成苯胺. 考察了不同催化剂、反应温度及反应时间等因素的影响. 在以Pt/Al2O3为催化剂,反应温度220 ℃和反应时间3 h的条件下,硝基苯的转化率可达99.3%, 苯胺的选择性为99.8%, 催化剂表现出较高的加氢活性和选择性.     

1H NMR and Calorimetric Studies of the Inclusion of Trimethylammonium Cations into Water Soluble Calixresorcinarenes

Abstract

The complexation of tetramethylammonium (TEMA), benzyltrimethylammonium (BTMA), p-nitrobenzyltrimethylammonium (BTMAN) and N, N, N-trimethylanilinium (TMA) by the tetrasulphonate derivative of the resorcinol cyclic tetramer (1), was studied in aqueous solution by ¹H NMR and calorimetry. Host 1 specifically recognizes the—N⁺ (CH₃)₃ group of TEMA, BTMA and BTMAN, whereas it binds TMA unselectively; TMA is included both via the charged group and the aromatic moiety. The binding constants of all four guests with 1, as determined by both ¹H NMR and calorimetric titrations, show that all inclusion processes are almost equally stabilised.

ΔHΔ and ΔSΔ values, determined by direct calorimetry, reveal specific interactions that are not expressed in the ΔGΔ terms and indicate that we are dealing with “non-classical hydrophobic effects”. The effects of the structural, conformational and electronic properties of the guests on the forces driving the inclusion processes are discussed.     

Exchanged Cations and Water during Reactions in Polypyrrole Macroions from Artificial Muscles

The movement of the bilayer (polypyrrole–dodecylbenzenesulfonate/tape) during artificial muscle bending under flow of current square waves was studied in aqueous solutions of chloride salts. During current flow, polypyrrole redox reactions result in variations in the volumes of the films and macroscopic bending: swelling by reduction with expulsion of cations and shrinking by oxidation with the insertion of cations. The described angles follow a linear function, different in each of the studied salts, of the consumed charge: they are faradaic polymeric muscles. The linearity indicates that cations are the only exchanged ions in the studied potential range. By flow of the same specific charge in every electrolyte, different angles were described by the muscle. The charge and the angle allow the number and volume of both the exchanged cations and the water molecules (related to a reference) between the film to be determined, in addition to the electrolyte per unit of charge during the driving reaction. The attained apparent solvation numbers for the exchanged cations were: 0.8, 0.7, 0.6, 0.5, 0.5, 0.4, 0.25, and 0.0 for Na⁺, Mg²⁺, La³⁺, Li⁺, Ca²⁺, K⁺, Rb⁺, and Cs⁺, respectively.     

into the Role of Additives in Catalytic Synthesis of Insight Cyclohexylamine from Nitrobenzene

Cyclohexylamine is a versatile intermediate in various chemical industries,which can be expediently synthesized via hydrogenation of aniline or nitrobenzene.However,such processes always suffer from side reactions.Many reports have found that specific additives can suppress the formation of side products,but the mechanism is still not clear.In this work,results suggest that it is the hydroxide ion of alkali metal hydroxides,rather than the cations,which plays a key role in suppressing the side reactions on supported Ru-based catalysts.With the assistance of LiOH,the selectivity toward cy- clohexylamine increased from 85.4% to 100%.Side products,such as dicyciohexylamine,cyclohexanol and N-isopropyl cyclohexylamine,could no longer be detected.Theoretical calculations further disclosed that addition of alkali metal hydroxides inhibited the dissociation of enamine and decreased the adsorption energy of cyclohexylamine,which might be the reasons for a better selectivity.However,the addition of alkali metal hydroxides reduced the activity of nitrobenzene hydrogenation by unfolding the condensation reaction route.To recover or even further enhance the catalytic performance,a second metal component was introduced and the resultant RuNi/AC exhibited a significant improvement in activity compared with Ru/AC.     

Extraction by Mixed Solvent and Spectrophotometric Determination of Sodium Dodecyl Sulfate in Sea Water

Mixed solvent was used to extract ion pairs formed from suitable cationic dye and sodium dodecyl sulfate in sea water. The extracts were used for spectrophotometric determinations. The extraction of ion pairs of various combinations is discussed. Ethyl violet and a mixture (1:1) of p-xylene and toluene are the most useful combination as the cationic dye and the extraction solvent. The extracts were determined spectrophotometrically at 611.2 nm; the molar absorptivity is 1.27 × 10⁵ M^?1 cm^?1. The detection limit is 2.0 ppb in water based on three times the standard deviation of the blank. Extraction with this mixed solvent is as rapid and sensitive as with the best single solvent.     

Quantum-Chemical Analysis of Coordination of Dimethylsulfoxide Molecules to Sodium and Potassium Cations

Coordination of dimethylsulfoxide molecules to the sodium and potassium cations was investigated by HF/6-31G(d)//HF/6-31G(d) and DFT(B3LYP/6-31G(d)) quantum-chemical methods. The coordination numbers of Na⁺ and K⁺ are found to be five and six, respectively. Thermal effects of complexation were calculated for each stage of the process; these were found to be 197.8, 160.1, 106.9, 88.0, 53.9 [HF/6-31G(d)] and 195.0, 158.5, 108.9, 95.7, 60.0 kJ/mole [B3LYP/6-31G(d)] for Na⁺ (one to five DMSO molecules, respectively); 146.6, 118.7, 90.2, 68.9, 70.0, 49.0 [HF/6-31G(d)] and 144.0, 117.4, 91.7, 78.9, 78.6, 56.4 kJ/mole [B3LYP/6-31G(d)] for K⁺ (one to six DMSO molecules, respectively). Structural parameters and charge distributions are given for the complexes. It is shown that solvation of sodium and potassium cations by DMSO molecules is preferable to solvation by water molecules.     

离子色谱法测定不同地区家庭饮用井水中的阴、阳离子

采用离子色谱法测定不同地区家庭饮用井水中氟离子、氯离子、硝酸根、硫酸根、钠离子、钾离子、镁离子和钙离子等8种阴、阳离子的含量。样品经IonPac AS11-HC型分离柱及IonPac AG11-HC型保护柱分离,以30mmol·L-1氢氧化钾溶液为淋洗液(阴离子分析);样品经IonPac CS12A型分离柱及IonPac CG12A型保护柱分离,以20 mmol·L-1甲基磺酸溶液为淋洗液(阳离子分析);采用电导检测器检测。8种离子在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3s)在0.002~0.034mg·L-1之间。对井水样品进行测定,测定值的相对标准偏差(n=6)在0.59%~2.0%之间。用标准加入法做方法的回收试验,计算得回收率在98.3%~109%之间。