Extraction of cations as salts of fatty acids : Analytical and chromatographic separation of beryllium from iron and aluminium

Quantitative extractions of aluminium and ferric ions are carried out in presence of butyric acid. A method has been given for quantitative extraction of beryllium from aluminium and ferric ion in presence of ethylenediaminetetra-acetic acid. Interference has been studied and interference due to phosphate has been avoided by addition of zirconium salt. The method has been applied to thc analysis of beryl.     

Self-assembly of fatty acids and hydroxyl derivative salts

We report the dispersions of a fatty acid and hydroxyl derivative salts in aqueous solutions that were further used to produce foams and emulsions. The tetrabutyl-ammonium salts of palmitic acid, 12-hydroxy stearic acid, and omega-hydroxy palmitic acid formed isotropic solutions of micelles, whereas the ethanolamine salts of the same acids formed turbid birefringent lamellar solutions. The structure and dimension of those phases were confirmed by small-angle neutron scattering and NMR. Micelles exhibited a surprisingly small radius of about 20 A, even for hydroxyl fatty acids, suggesting the formation of hydrogen bonds between lipids in the core of the micelles. In the case of ethanolamine salts of palmitic and 12-hydroxy stearic acids, the lipids were arranged in bilayers, with a phase transition from gel to fluid upon heating, whereas for omega-hydroxy palmitic acid, monolayers formed in accordance with the bola shape of this lipid. Foams and emulsions produced from ethanolamine salt solutions were more stable than those obtained from tetrabutyl-ammonium salt solutions. We discuss these results in terms of counterion size, lipid molecular shape, and membrane curvature.     

Surface-tension titration of metal ions by using metal salts of fatty acids as surface-active indicators

Summary The use of calcium and zinc salts of stearic, palmitic and myristic acids as surface-active indicators has been investigated in various buffer solutions. The back titration of nickel(II), cobalt(II) and their mixture with calcium chloride and the direct titration of copper(II) with EDTA has been successfully performed by using calcium palmitate and calcium stearate, respectively, as surface-active indicator. The end point, which is indicated by a remarkable change in surface tension, agrees well with the equivalence point.

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Oberflächenspannungstitration von Metallionen unter Anwendung von Fettsäure-Metallsalzen als oberflächenaktive Indicatoren

Zusammenfassung Die Verwendung der Calcium- und Zinksalze von Stearin-, Palmitin- und Myristinsäure als oberflächenaktive Indicatoren ist in verschiedenen Pufferlösungen untersucht worden. Die Rücktitration von Nickel(II), Cobalt(II) und ihrem Gemisch mit Calciumchlorid und die direkte Titration von Kupfer(II) mit EDTA sind mit Calciumpalmitat bzw. -stearat als oberflächenaktiver Indicator erfolgreich durchgeführt worden. Der Endpunkt, der durch eine beachtliche Änderung der Oberflächenspannung indiziert wird, stimmt gut mit dem Äquivalenzpunkt überein.

     

Extraction of dissolved fatty acids from sea water

Summary During a cruise in the Baltic Sea in March/April 1991, dissolved lipids were concentrated from acidified sea water by adsorption on reversed phase material; the free fatty acids in the lipids were isolated. Titration of the acids with 0.01 mol/l methanolic KOH resulted in a very poor titration curve; assessing total concentration of organic acids in sea water by base titration appears to be impractical. After derivatization with p-phenylphenacyl bromide under crown ether catalysis the fatty acids were analyzed by micro-bore HPLC with UV-detection and comparison with standard reference substances. Some unknown fatty acids were characterized by GC/MS. Total concentrations were in the range from 1 to 4.5 nmol/l. They were the same in parallel samples liquid/liquid extracted with dichloromethane. The HPLC spectra of the fatty acids in both kinds of samples were also quite similar. This confirms earlier observations that adsorptive concentration of dissolved fatty acids and non-polar lipids from sea water is as effective as liquid/liquid extraction. Higher amounts of fatty acids can be concentrated by adsorption from large water volumes, thus lowering detection limits. Palmitic acid had by far the highest concentration in every sample followed by myristic acid, lauric acid, and stearic acid. Palmitoleic acid and oleic acid were the most abundant unsaturated acids. The other saturated and unsaturated acids had medium to low concentrations.     

Thermal investigations of the calcium salts of monocarboxylic aliphatic fatty acids

Calcium salts of acetic and mono, di and trichloroacetic acids were investigated with respect to their dehydration and decarboxylation, using a derivatograph. A phase transition was noticed only in the case of calcium acetate. Effects of crucible and diluent on the thermal behaviour of the above salts were also studied. The decomposition products were investigated qualitatively, and from these gaseous products and also from the residue after pyrolysis the probable mechanisms of decompositions have been suggested. Activation energies for the decarboxylation processes were evaluated from the TG curves.

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Zusammenfassung Die Calciumsalze von EssigsÄure sowie von Mono-, Di- und TrichloressigsÄure wurden mittels eines Derivatographen hinsichtlich ihrer Dehydratisierung und Decarboxylierung untersucht. Ein Phasenübergang wurde nur im Falle des Calciumacetats beobachtet. Der Effekt des Tiegels und des Verdünners auf das thermische Verhalten obiger Salze wurde ebenfalls untersucht. Die Zersetzungsprodukte wurden qualitativ geprüft und aus diesen gasförmigen Produkten sowie aus ihren Pyrolyseresten wurde ein wahrscheinlicher Zersetzungsmechanismus vorgeschlagen. Die Aktivierungsenergien der DecarboxylierungsvorgÄnge wurden aus den TG-Kurven ermittelt.

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Résumé La déhydratation et la décarboxylation des sels de calcium des acides acétique, mono, di et trichloroacétique ont été étudiées à l'aide d'un Derivatograph. Seul l'acétate de calcium présente une transition de phase. Les effets respectifs du creuset et du diluant sur le comportement thermique de ces sels ont également été suivis. Les produits de décomposition ont été analysés qualitativement. D'après la nature des gaz émis et celle des résidus de pyrolyse, un mécanisme est proposé pour ces décompositions. Les énergies d'activation des réactions de décarboxylation sont calculées à partir des courbes TG.

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The authors express their most grateful thanks to the Council of Scientific and Industrial Research, New Delhi, for financial assistance.     

The structures of Langmuir-Blodgett films of fatty acids and their salts

Recent advances in several experimental techniques have enabled detailed structural information to be obtained for floating (Langmuir) monolayers and Langmuir-Blodgett films. These techniques are described briefly and their application to the study of films of fatty acids and their salts is discussed. Floating monolayers on aqueous subphases have been shown to possess a complex polymorphism with phases whose structures may be compared to those of smectic mesophases. However, only those phases that exist at high surface pressures are normally used in Langmuir-Blodgett (LB) deposition. In single LB monolayers of fatty acids and fatty acid salts the acyl chains are in the all-trans conformation with their long axes normal to the substrate. The in-plane molecular packing is hexagonal with long-range bond orientational order and short-range positional order: known as the hexatic-B structure. This structure is found irrespective of the phase of the parent floating monolayer. The structures of multilayer LB films are similar to the structures of their bulk crystals, consisting of stacked bilayer lamellae. Each lamella is formed from two monolayers of fatty acid molecules or ions arranged head to head and held together by hydrogen bonding between pairs of acids or ionic bonding through the divalent cations. With acids the acyl chains are tilted with respect to the substrate normal and have a monoclinic structure, whereas the salts with divalent cations may have the chains normal to the substrate or tilted. The in-plane structures are usually centred rectangular with the chains in the trans conformation and packed in a herringbone pattern. Multilayer films of the acids show only a single-step order-disorder transition at the melting point. This temperature tends to rise as the number of layers increases. Complex changes occur when multilayer films of the salts are heated. Disorder of the chains begins at low temperatures but the arrangement of the head groups does not alter until the melting temperature is reached. Slow heating to a temperature just below the melting temperature gives, with some salts, a radical change in phase. The lamellar structure disappears and a new phase consisting of cylindrical rods lying parallel to the substrate surface and stacked in a hexagonal pattern is formed. In each rod the cations are aligned along the central axis surrounded by the disordered acyl chains.     

Extraction of fatty acids from grape seed by superheated hexane

Superheated hexane extraction has been tested for obtaining fatty acids from grape seed and compared with conventional Soxhlet and hot hexane extractions. Seeds from grape residues from a winery were dried for 46 h at 105 °C, milled and sieved by particle size (d < 0.42 mm, 0.42 < d < 0.84 mm and d > 0.84 mm). An optimization study of influential variables on superheated hexane extraction (namely extraction time, temperature, pression, particle size and sample amount) was carried out by a multivariate approach. All the extracts were concentrated in a rotary evaporator and dried by adding 1 g of Na₂SO₄. Then, 2 ml of the dried extract were subjected to reaction with 1 ml of a 0.5 M solution of sodium methylate in methanol to obtain fatty acid methyl esters (FAMEs). After derivatization, FAMEs were quantified by GC-FID. The results show that the optimal conditions for superheated hexane extraction are: time extraction, 10 min; temperature, 80 °C; pressure, 40 bar; particle size, d < 0.42 mm; amount of sample, 0.4 g. Under these conditions, around 84% of the fatty acids (out of the amount obtained by Soxhlet extraction) is extracted. Comparison with Soxhlet and hot hexane extractions showed that the percentages of FAMEs are similar in all the extracts and they agree with the data in the bibliography.     

Hetarylation of pyrazolones by salts of N-acylheteroaromatic cations

Isoquinoline, acridine, benzimidazole, and benzoxazole residues were introduced into the pyrazolone ring by reaction of N-heteroaromatic compounds with pyrazolones in the presence of acylating agents.See [1] for our preliminary communication [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1394–1397, October, 1977.     

Self-assembly of fatty acid-alkylboladiamine salts

Long-chain fatty acids are insoluble in aqueous solution and form crystal precipitates. It is then of particular importance to determine the physicochemical parameters allowing their dispersion in water to improve their bioavailability and their utilization as surfactants. Herein, we report a study on salt-free catanionic systems in aqueous solution made of mixtures between palmitic or stearic fatty acids and alkylboladiamines (Abd's) differing by their alkyl chain length. Phase contrast microscopy, solid-state NMR, Fourier transform infrared spectroscopy, and small-angle neutron scattering were used to characterize the phase behavior of these systems at molar ratio of fatty acid to Abd of 1 and 2. Whatever the Abd and the molar ratio, fatty acids were embedded at low temperature in a bilayer gel phase which crystallizes after a period of rest. At an equimolar ratio, the gel phases transited upon raising the temperature to an isotropic phase made of worm-like micelles except in the case of the ethylenediamine chain for which a lamellar fluid phase was observed. At a molar ratio of 2 and high temperature, fatty acids were embedded in a lamellar fluid phase which self-orients with its stacking axis perpendicular to the magnetic field. However, for a long alkylboladiamine such as spermine, worm-like micelles formed. The phase behavior at high temperature is discussed in terms of molecular volume.     

Zwitterionic amino acids as precursors for nonmetal cation pentaborate salts

Nonmetal cation (NMC) pentaborate structures were synthesized using the amino acid molecules as cations precursors. Chemical composition analysis, infrared spectroscopy, mass analysis, boron nuclear magnetic resonance, and thermal gravimetric analysis (TGA/DTA) methods were used for structural characterization. The hydrogen storage efficiency of molecules was also determined experimentally. The recorded infrared spectra support the structural similarities of the molecules. Stretchings of pentaborate rings and characteristic peaks of amino acids were detected in infrared spectra. When the thermal analysis curves were recorded, it was found that the structures showed similar decomposition steps. Due to the result of thermal decay, glassy boron oxide (B₂O₃) formation was observed as the final decomposition products of all molecules. Peaks associated with boric acid, triborate, and pentaborate were observed in the ¹¹B spectra of these salts. Powder X-ray diffraction spectroscopy supports the presence of BO₃ and BO₄⁻ groups regarding the presence of pentaborate rings. It also indicates the high crystallinity of the structures. The molecular cavities detected by brunauer–emmett–teller analysis were found to be 3.586, 1.922, 1.673, and 1.923 g/cm³. Low-molecular cavities can be attributed to the high hydrogen-bonding capacity of the structures. The hydrogen capture efficiency of the pentaborate salts was found to be in the range of 0.039-0.     

Thermochemical study of gaseous salts of oxygen-containing acids: XIX. Tin salts

Reactions of the gas-phase synthesis of tin vanadates, borates, and molybdates were studied. Standard enthalpies of formation and atomization of gaseous salts SnV₂O₆, SnB₂O₄, Sn₂B₂O₅, SnMoO₄, Sn₂MoO₅, and SnMo₂O₇ were determined.     

Extraction of pertechnetate with tetraphenylphosphonium in the presence of various acids, salts and hydroxides

Solvent extraction of pertechnetate anions from aqueous solutions of some mineral acids (HCl, HNO₃, HClO₄, H₂SO₄), (NaCl, NaNO₃, NaClO₄, K₂CrO₄, NaCO₃), NaOH and NH₄OH by tetraphenylphosphonium chloride in chloroform and nitrobenzene was studied. The results are presented in the form of the dependencies of extraction characteristics of TcO ₄ ⁻ (distribution ratio, percentage of extraction) on the (C₆H₅)₄PCl, H⁺ and competitive anion concentrations. The solvent extraction of sub-and super-stoichiometric ratio of TcO ₄ ⁻ : (C₆H₅)₄P⁺ was performed. The extraction constant values of ion pairs TcO ₄ ⁻ −Cl⁻, TcO ₄ ⁻ −NO ₃ ⁻ , TcO ₄ ⁻ −ClO ₄ ⁻ and of individual anions TcO ₄ ⁻ , Cl⁻, NO ₃ ⁻ , ClO ₄ ⁻ were calculated.     

Biosynthesis of iso-fatty acids in myxobacteria: iso-even fatty acids are derived by alpha-oxidation from iso-odd fatty acids

The biosynthesis of iso-fatty acids was investigated in the myxobacteria Myxococcus xanthus and Stigmatella aurantiaca by feeding labeled precursors of these fatty acids and by conducting detailed analysis of the fatty acid profiles and fatty acid MS and NMR spectra. These experiments revealed that in S. aurantiaca all iso-even fatty acids are formed via alpha-oxidation of iso-odd fatty acids and not by using valine-derived isobutyryl-CoA.     

Hexafluorotitanate salts containing organic cations: use as a reaction medium and precursor to the synthesis of titanium dioxide

The straightforward modification of commercial hexafluorotitanic acid with organic derivatives containing a tetraalkylammonium cation produced stable precursor solutions with only a small fraction of water, which were then used as a reaction medium for the synthesis of nanocrystalline TiO(2).     

Vinamidinium salts of N-substituted aminoacetic acids

Formylation of N-phthaloylglycine with the POCl3-DMF system afforded N,N,N′, N′-tetramethyl-2-(N-phthaloyl)vinamidinium perchlorate (2). X-ray diffraction study showed that molecule 2 is planar and contains two equivalent nitrogen atoms in the three-carbon vinamidinium fragment. Salt 2 undergoes transamination with primary aromatic amines to give the corresponding bis-azomethines. The reactions with hydrazines produce substituted 4-aminopyrazoles. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 832–835, May, 2006.     

Frovatriptan salts of aliphatic carboxylic acids

The interaction of the antimigraine pharmaceutical agent frovatriptan with acetic acid and succinic acid yields the salts (±)‐6‐carbamoyl‐N‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐3‐aminium acetate, C₁₄H₁₈N₃O⁺·C₂H₃O₂⁻, (I), (R)‐(+)‐6‐carbamoyl‐N‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐3‐aminium 3‐carboxypropanoate monohydrate, C₁₄H₁₈N₃O⁺·C₄H₅O₄⁻·H₂O, (II), and bis[(R)‐(+)‐6‐carbamoyl‐N‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐3‐aminium] succinate trihydrate, 2C₁₄H₁₈N₃O⁺·C₄H₄O₄²⁻·3H₂O, (III). The methylazaniumyl substitutent is oriented differently in all three structures. Additionally, the amide group in (I) is in a different orientation. All the salts form three‐dimensional hydrogen‐bonded structures. In (I), the cations form head‐to‐head hydrogen‐bonded amide–amide catemers through N—H...O interactions, while in (II) and (III) the cations form head‐to‐head amide–amide dimers. The cation catemers in (I) are extended into a three‐dimensional network through further interactions with acetate anion acceptors. The presence of succinate anions and water molecules in (II) and (III) primarily governs the three‐dimensional network through water‐bridged cation–anion associations via O—H...O and N—H...O hydrogen bonds. The structures reported here shed some light on the possible mode of noncovalent interactions in the aggregation and interaction patterns of drug molecule adducts.