Salting-out thin-layer chromatography of transition metal complexes. IV: Effect of sorbent on the behaviour of mixed aminocarboxylato cobalt (III) complexes

Summary From literature data for 14 mixed aminocarboxylato cobalt(III) complexes, the effect of the sorbent on R_M values, salting-out efficiency (m) and separation factors () of adjacent members of homologous series was investigated in salting-out, thin-layer chromatography on silica gel, polyacrylonitrile and cellulose sorbents, using ammonium sulphate solutions as developers. For complexes belonging to the same homologous series, linear dependence was found between R_M,m and log values, respectively, on two different sorbents. Polyacrylonitrile was shown to be the most suitable sorbent for the separation of the complexes since it gave the highest values for R_M,m and .     

溶剂萃取1,2-环己二醇的盐效应

对萃取体系的盐效应进行了研究。选择了5种盐(AlCl3，Na2C2O4，Nacl，KCl，NaAc)作为研究对象，考察了其对有机溶剂乙酸乙酯和乙酸丁酯萃取水溶液中1，2-环己二醇的影响。结果表明盐对1，2-环己二醇萃取有两种影响．一种为盐的存在引起萃取剂的水解反应。造成1．2-环己二醇的萃取性能下降；另一种为盐的盐析作用。使1，2-环己二醇的萃取分配系数增加。同时建立了分配系数与盐浓度之间的关系式。     

The influence of different salting-out agents on the extraction of Ce,Eu, Gd,Tb using tri-n-butyl phosphate

The extraction enthalpies H ^o of Ce, Eu, Gd, Tb nitrates usingTBP in the presence of different salting-out agents in aqueous phase were determined. It was established that the extraction process is the most exothermic in the case of LiNO₃.

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Der Einfluß verschiedener Aussalzmittel auf die Extraktion von Ce, Eu, Gd und Tb mit Tri-n-butylphosphat

Zusammenfassung Es wurden die Extraktionsenthalpien H ^o von Ce-, Eu-, Gd- und Tb-Nitrat unter Verwendung vonTBP in Gegenwart verschiedener Aussalzmittel in wäßriger Phase bestimmt. Es wurde festgestellt, daß der Extraktionsprozeß im Fall von LiNO₃ am meisten exotherm verläuft.

     

Reversed-phase thin-layer chromatography of various pesticides in the presence of water-soluble beta-cyclodextrin polymer

Summary The modification of the hydrophobicity of 28 commercial pesticides with a water-soluble -cyclodextrin polymer (SCDP) in the presence of aqueous NaCl has been studied by reversed-phase thin-layer chromatography. The pesticides formed inclusion complexes with SCDP and these complexes are less lipophilic than the parent pesticides. The sodium chloride exerted a typical saltingout effect, the retention of each pesticide increased with increasing concentration of the salt in the eluent. This effect can be tentatively explained by the suppression of the dissociation of the polar groups in the solute molecules resulting in increased apparent lipophilicity. The correlation between lipophilicity and salting-out effect was found to be significant, that is the salting-out effect increases with increasing polarity (lower lipophilicity) of the pesticides, whereas the lipophilicity has negligible influence on the inclusion-forming capacity of non-homologous series of pesticides.     

Effect of NaOH on the solubility of fluorocarbon in alcohol–NaOH systems

We propose a dechlorination process that allows safe and environmental conversion of chlorinated fluorocarbons. Starting with dissolving a fluorocarbon in an alcohol–NaOH solution, the fluorocarbons are reacted with alcohol–NaOH solvents at room temperature and pressure. In this work, the effect of the NaOH concentration on the solubility of CCl₂F₂ (CFC-12), CH₂F₂ (HFC-32), C₂HF₅ (HFC-125), C₂H₂F₄ (HFC-134a) and C₂H₄F₂ (HFC-152a) in methanol–NaOH, ethanol–NaOH and 1-propanol–NaOH solutions was measured. The experimental salting-out effects can be explained by solvation of a few alcohol molecules on sodium ion. Setchenov coefficients were determined and found to be independent of temperature.     

Removing proteins from an aerated yeast fermentation by pulsing carbon dioxide

Salting-out is a common technique used for precipitating proteins and other materials from fermentation and tissue culture processes. It leaves a salt residue in the system. Foam fractionation can also be used to remove proteins by protein precipitation from a dilute solution. In doing so, there is usually a trade-off between enrichment and recovery. An increase in the airflow rate will increase the recovery, but only at the expense of the enrichment. A new method for increasing the recovery in foam fractionations and in yeast fermentations is to add a burst of CO₂ to the process and then restore the air. This CO₂ acts like a temporary salt, but it does not leave behind a residue. The recovery increases as a result of the joint use of these gases, perhaps by more than 10-fold, without sacrificing the enrichment. Chicken egg albumin in a foam fractionation column can serve as a simple, experimental model for the proposed recovery process in lieu of the fermentation process.     

Estimation of Silica Species’ Concentrations in Lithium and Magnesium Chloride Solutions from the Peak Intensities Observed by FAB-MS

The concentrations of dissolved silica species in electrolyte solutions were derived from the relative intensities of silica species, obtained from FAB-MS measurements (fast atom bombardment mass spectrometry), and the total concentration of dissolved silica. Generally, silica species in aqueous solutions form various complexes with cations such as sodium (Na⁺) or calcium (Ca²⁺), and it has been difficult to determine the concentration of each species. From the observed results from FAB-MS, the chemical species of silica dissolved in lithium chloride (LiCl) and magnesium chloride (MgCl₂) solutions do not include complexes with these cations, and thus Li⁺ and Mg²⁺ do not replace protons of the silanol groups in silica. Therefore, in LiCl and MgCl₂ solutions, all of the simple structures of silicate species can be identified. The concentration of each silica species was estimated on the basis of its mass spectra peak intensities and the total concentration of silica as determined by colorimetry. This study yields the concentration of each silica species within small errors, whereas conventional methods (such as ²⁹Si-NMR) have not yielded the concentrations of individual silica species. From these results, dimers and cyclic tetramers are concluded to be the main species in silica solutions with concentrations of at most 0.1 to 0.2 μmol⋅dm⁻³. This tendency should also occur in NaCl and CaCl₂ solutions, which are major electrolytes in natural waters.     

Selective extraction of thallium(III) in the presence of gallium(III), indium(III), bismuth(III) and antimony(III) by salting-out of an aqueous mixture of 2-propanol

Thallium(III), in the presence of other triply charged ions such as gallium, indium, bismuth and antimony in aqueous solution, was quantitatively and selectively extracted into 2-propanol/water phase by addition of NaCl ranging from 2.5 to 4.0 mol dm⁻³. The extraction efficiencies of gallium, indium, bismuth and antimony were much lower than that of thallium(III). Thus a maximal selective separation of thallium(III) from these elements could be attained using a 2-propanol/water mixture. Thallium(III) was extracted as TlCl₄⁻ with Na⁺. The detailed extraction mechanism in the presence of chloride, water in the organic phase and counter ions is discussed.     

Ionic Liquids in Polyethylene Glycol Aqueous Solutions: Salting-in and Salting-out Effects

Summary. Changes of the fluid phase behaviour of polyethylene glycol (PEG) aqueous solutions – viz. critical solution temperature shifts at atmospheric pressure – were produced by the addition of different ionic liquids, namely 1-ethyl-3-methylimidazolium ethyl sulfate and 1-alkyl-3-methylimidazolium chloride (alkyl = ethyl to decyl). The addition of ionic liquids with long alkyl chains improves the solubility of PEG in water (salting-in effect), whereas the impact of short-chain ionic liquids is usually the contrary (salting-out effect). The results are interpreted taking into account the kosmotropic (water-structuring) or chaotropic (water-structure-breaking) nature of ionic liquids, as compared to other inorganic salts.