Phosphoric Acid Esters Research Articles

Final Report on the Safety Assessment of Lecithin and Hydrogenated Lecithin

Lecithin is a naturally occurring mixture of the diglycerides of stearic, palmitic, and oleic acids, linked to the choline ester of phosphoric acid, commonly called phosphatidylcholine. Hydrogenated Lecithin is the product of controlled hydrogenation of Lecithin. Bilayers of these phospholipids in water may form liposomes, a spherical structure in which the acyl chains are inside and not exposed to the aqueous phase. Lecithin and Hydrogenated Lecithin are used in a large number of cosmetic formulations as skin conditioning agents-miscellaneous and as surfactant-emulsifying agents. Hydrogenated Lecithin is also used as a suspending agent-nonsurfactant. Historical data on concentration of use of Lecithin reveals that 0.1% to 1.0% is the concentration range most frequently seen, with concentrations up to 50% reported for two moisturizing products. A solution of 65% Lecithin is currently reported to be used at concentrations up to 3% in cosmetics. Nonocclusive application of Lecithin-containing liposomes to murine skin resulted in 30% penetration to the subdermis. In piglet skin, the same application resulted in 99% accumulating in the stratum corneum. In general, liposomes are considered effective in capturing other compounds inside their spherical structure and delivering any such captured compound through the skin barrier. As a result, caution should be exhibited in formulating cosmetic products that contain these ingredients in combination with other ingredients whose safety is based on their lack of absorption or where dermal absorption is a concern. Lecithin is virtually nontoxic in acute oral studies, short-term oral studies, and subchronic dermal studies in animals. Lecithin is not a reproductive toxicant, nor is it mutagenic in several assays. In an oral carcinogenicity study, brain neoplasms were found in mice exposed to Lecithin. In a subcutaneous carcinogenicity study, no neoplasms were found in mice and rats exposed to Lecithin. Adverse reactions to Lecithin in a metered-dose inhaler have been reported. Lecithin and Hydrogenated Lecithin were generally nonirritating and nonsensitizing in animal and human skin. Based on the available data, Lecithin and Hydrogenated Lecithin are safe as used in rinse-off cosmetic products; they may be safely used in leave-on products at concentrations up to 15%, the highest concentration tested in clinical irritation and sensitization studies; but the safety of use could not be substantiated in cosmetic products likely to be inhaled. Because of the possibility of formation of nitrosamines, these ingredients should not be used in cosmetic products in which N-nitroso compounds may be formed.

Dihydrophilic block copolymers with ionic and nonionic blocks. I. Poly(ethylene oxide)-b-polyglycidol with OP(O)(OH)2, COOH, or SO3H functions: Synthesis and influence for CaCO3 crystallization

Dihydrophilic block copolymers of poly(ethylene oxide)-b-polyglycidol were prepared and polyglycidol blocks converted into ionic blocks containing OP(O)(OH)2, COOH, or SO3H groups. Although phosphorylation of polyhydroxy compounds with POCl3 usually leads to insoluble products, phosphorylation of poly(ethylene oxide)-b-polyglycidol using a POCl3/OH ratio equal to 1/1 gave soluble products, predominantly monoester of phosphoric acid (after hydrolysis) (provided that the reaction was conducted in triethyl phosphate as solvent). All copolymers were characterized by 1H NMR, 13C NMR, and/or 31P NMR spectra for confirming their structure. The degree of substitution was determined from quantitative 13C NMR spectroscopy (inverted-gate decoupling-acquisition mode). Preliminary results indicate that from these three groups of block copolymers the phosphoric acid esters are the most effective ones at least in controlling the growth of CaCO3 crystals in aqueous solution. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 955–963, 2001

The effect of solvent and proton donor type on the conductivity and physico-chemical properties of poly(vinylidene fluoride)-based proton-conducting gel electrolytes

In the present work proton-conducting gels based on commercially available poly(vinylidene fluoride) (PVdF) system are studied. The polymer, H 3PO 4 and phosphoric acid organic esters (used as proton donors) are dissolved in dimethylformamide (DMF) or dimethyl acetate (DMA) at ambient temperatures and than cast on the flat glass substrate. Highly conducting (∼10 −3 S cm −1 at 20°C) colorless polymeric membranes are obtained in a relatively narrow PVdF and proton donor concentration ranges. The highest conductivities have been obtained when phosphoric acid esters are used as proton donors. Conductivities measured for systems containing DMF are slightly higher than for DMA-based derivatives. The gel electrolytes studied are thermally stable up 100°C as shown by the DSC experiments. The interactions between H 3PO 4 and solvents used are studied by means of FT-IR spectroscopy which shows the possibility of the protonation of solvent molecules by H 3PO 4. Therefore, the possibility of proton transportation via the Grotthus-type mechanism cannot be excluded.

Chemical degradation of polyurethanes. II. Degradation of microporous polyurethane elastomer by phosphoric acid esters

Microporous polyurethane elastomer, based on 4,4′-diphenylmethane diisocyanate and polyester polyol Bayflex 2003 (Bayer AG), was degraded by phosphoric acid esters (CH3CH2O)3P(O) and (ClCH2CH2O)3P(O) at 180°C. Structure of degraded products was investigated by means of 1H-, 13C-, and 31P-NMR spectroscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 886–893, 2000

Uranyl-selective electrode based on a new bifunctional derivative combining the synergistic properties of phosphine oxide and ester of phosphoric acid

Ion-selective electrodes based on the bifunctional chelating agent O-methyldihexylphosphine oxide O'-hexyl-2-ethylphosphoric acid (HL) incorporated into a poly(vinyl chloride) membrane were developed. This new derivative is proposed as a single molecular unit combining the overall properties of the synergistic single components, di-2-ethylhexylphosphoric acid and trioctylphosphine oxide. Two different ionophores, HL and its uranyl complex (UO2L2), were studied. The response of the electrodes to uranyl ion was Nernstian for UO2L2 and super-Nernstian for HL ionophores, with detection limits of 3.0 x 10(-6) and 2.0 x 10(-5) M, respectively. Results indicate a more effective interaction with the analyte in the case of having a unique molecule incorporating the two functional groups immobilized into a polymeric membrane, rather than the separated two synergistic ligands. Flow-through tubular electrodes based on both ionophores were also used as potentiometric detectors in flow injection techniques.

( E)-1,1,1-trifluoro-4-phenyl-but-2-ene-4-one and trimethyl phosphite

The interaction of ( E)-1,1,1-trifluoro-4-phenyl-but-2-ene-4-one ( 1) with trimethyl phosphite affords in a [4 + 1] cycloaddition the 1,2 λ 5-oxaphospholene 2 as a sole product which upon hydrolysis is transformed into the fluoroalkyl containing γ-ketophosphonate 4. When the reaction is carried out in the presence of small mounts of water, in addition to 2 as a main product, the phosphoric acid ester 6 of the enolic dimer of ketone 1 is also formed. The molecular structure of compound 6 (monoclinic P 2(1)/c with a = 2088.60(2), b = 1403.1(3), c = 1613.8(1) pm, α = 90, β = 100.97(1), γ = 90°, Z = 8) was determined, indicating two independent molecules with (RR) and (SS) configuration and disordered CF 3 groups.

Properties of vapor-deposited borophosphorosilicate glass layers employed in technology of silicon integrated circuits

The data of investigations on the physicochemical and electrophysical properties of borophosphosilicate glass layers deposited from mixtures of tetraethoxysilane and esters of boric and phosphoric acids in an oxygen-ozone medium (temperature, 400–440°C; atmospheric and subatmospheric pressures) have been generalized. The empirical relationships are obtained for determining the boundaries of the optimum dopant concentration region when the glass is used as a reflow interlayer dielectric in integrated circuit technology. The assumption is made that the structure of borophosphosilicate glass layers is formed by a porous network involving dopant clusters.

Structural Chemistry of Self-Assembled Monolayers of Octadecylphosphoric Acid on Tantalum Oxide Surfaces

Octadecylphosphoric acid ester is shown to self-assemble on amorphous/nanocrystalline tantalum oxide (Ta2O5) layers deposited by physical vapor deposition onto glass substrates. Three complementary surface-analytical techniques (angle-dependent X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and atomic force microscopy in lateral force mode), showed that a 2.2 nm thick, “tails-up”-oriented adlayer is formed, which displays local near-hexagonal order, strong P−O−Ta bonding, and the presence of (−P−O-)2Ta species. A model for the binding and the structural organization of the octadecyl phosphate molecules on the tantalum oxide surface is proposed involving direct coordination of the terminal phosphate headgroup to Ta(V) cations forming a strong complexation bond, two types of bonding of the octadecyl phosphate with both monodentate and bidentate phosphate-Ta(V) coordinative interactions, and, locally, the formation of a coincidence lattice of approximately hexagonal structure defined by both the location of Ta(V) cation sites and an intermolecular spacing between the octadecyl phosphate ligands of approximately 0.5 nm. This is very similar to the self-assembled monolayer structure of long-chain alkanethiols on gold. The use of phosphoric acid ester derivatives is believed to have potential for designing specific interface architectures in sensor technology, in surface modification of oxide-passivated metallic biomaterials, and in composite metal (oxide)−polymer interfaces.

Electrochemical syntheses in absolute alcohols (Review)

The data on electrosyntheses occurring in absolute aliphatic alcohols, including those involving alcohol molecules, are systematized. Syntheses of alcoholates and phosphoric acid esters, carbonylation, alkoxylation, and electrolyses of ketones and C-H acids in alcohol media are classified with these reactions. Mechanisms of the electrode reactions and their applications are discussed. Ninety references are included.

Geminal hydroxy phosphonate derivatives of nucleosides: A novel class of nucleoside 5′-monophosphate analogues

A novel type of phosphonate-based, isopolar, nonisosteric 5′-nucleotide analogue, the nucleoside 5′-hydroxy phosphonates, was prepared by Abramov nucleophilic addition of various phosphorous acid esters to nucleoside 5′-aldehydes. The newly formed compounds are distinguished by chirality of the 5′-carbon atom. The configuration of the 5′-epimers was assigned from NMR spectra.

Preparation of Heavy Metal Phosphates; Effect of Starting Precursors

Crystallization of heavy metal phosphates prepared from aqueous solutions is very slow. The situation could be improved when the salts were prepared from the respective metal alkoxide. The sol-gel synthesis of a group of these salts, (Zr, Ti, and Hf phosphates), from precursors of different natures was envisaged. By altering through metal precursors of different natures (inorganic or metallo-organic), and phosphate precursor of different natures (phosphoric acid or organic phosphate esters), we have shown that organic phosphates are also of advantage as the counterpart. Thermal analysis, FT-IR, and XRD results indicated more crystalline products when prepared from organic phosphates.

Process development for treatment of complex perovskite, ilmenite and rutile ores

The flotation processing characteristics of pervoskite, ilmenite and rutile from igneous and sedimentary ores were examined in the course of developing a commercial treatment process. Flotability of these minerals was found to be strongly influenced by a) flotation pH, b) pulp treatment before flotation, and c) type of collector. Modified ester-based collectors, such as phosphoric acid ester, were examined. When these collectors are modified with fatty alcohol ester sulphates, petroleum sulphonate or succinamate, their flotation performance is significantly improved. Efficient flotation of perovskite was achieved with phosphoric acid ester modified with fatty alcohol ester sulphate while ilmenite was floated with phosphoric acid ester modified with petroleum sulphonate. A mixture of phosphoric acid ester and succinamate was the most effective for rutile flotation. Modified phosphoric acid ester was evaluated in both laboratory and pilot plant testwork. Because of the complex gangue compositions of the ores tested, special attention was placed on the selection and evaluation of different gangue depressants. This paper summarizes progress in the development of new collectors for flotation of titanium minerals from complex titanium ores.

Surfactants as corrosion inhibitors for zinc pigment

A lamellar zinc pigment reacts in aqueous alkaline media (e.g. water‐borne paints) with the evolution of hydrogen. This corrosion reaction can be inhibited by certain surfactants. The most important structural part of the examined surfactants is the hydrophilic group; only anionic phosphate or phosphonate hydrophilic groups are effective corrosion inhibitors. Surfactants with carboxylate, sulfonate, amphoteric, cationic and non‐ionic hydrophilic groups are ineffective. There seems to be also an influence of the hydrophobic group of the surfactants because a partial ester of phosphoric acid with a fluorinated hydrophobic group was the most effective corrosion inhibitor in this study.

Melt/solution processable conducting polyaniline: doping studies with a novel phosphoric acid ester

Polyaniline (PANI) was doped with a novel dopant, 3-pentadecylphenylphosphoric acid (PDPPA), having a long hydrophobic hydrocarbon side chain, either by mechanical mixing of emeraldine base and PDPPA or by the emulsion polymerization route using xylene or chloroform as the solvent. The resulting PANI–PDPPA complexes obtained were characterised by FTIR, UV–Vis, conductivity measurements, XRD, SEM, DSC, TGA and polarised light microscopy. The formation of the complex induces solubility of PANI in commonly used weakly polar or non-polar organic solvents such as xylene, THF, chloroform, etc. Protonation gives a plasticized PANI–PDPPA complex which can be processed by both thermal and solution techniques. On thermal processing, a free-standing flexible film with conductivities of the order 1.8 S cm −1 was obtained.

A novel approach to oligodeoxyribonucleotides bearing phosphoric acid esters at the 3′-terminals via the phosphoramidite method with allyl protection: An efficient synthesis of base-labile nucleotide-amino acid and -peptide conjugates

A new method for synthesis of 3′-end-phosphorylated DNA oligomers via the phosphoramidite method with allyl protection has been developed. This method is particularly useful for the preparation of derivatives with base-labile structures such as oligoDNA-OPO(OH)OCH 2CH(R)Z, in which Z is an electron-withdrawing function. For example, a oligonucleotide-amino acid conjugate, 5′TGTCGACACCCAATT 3′-OPO(OH)OCH 2CH(NH 2)COOH, and a oligonucleotide-peptide conjugate, 5′TGTCGACACCCAATT 3′-OPO(OH)OCH 2CH(NH 2COOH, have been obtained in high purity.

An Immunomagnetic Electrochemical Sensor Based on a Perfluorosulfonate-Coated Screen-Printed Electrode for the Determination of 2,4-Dichlorophenoxyacetic Acid

A disposable immunomagnetic electrochemical sensor involving a magnetic particle-based solid phase and a Nafion film-coated screen-printed electrode (Nafion-SPE) stuck at the bottom of a polystyrene cylinder (microwell of 300 microL) was developed and evaluated in a competitive immunoassay of the widely used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The competitive binding of 2,4-D and 2,4-D labled with alkaline phosphatase (AP) for a limited amount of polyclonal anti-2,4-D antibody-coated magnetic beads was monitored electrochemically by measuring the AP labled++ activity bound to the beads. The phosphoric acid ester of [[(4-hydroxyphenyl)amino]-carbonyl]cobaltocenium hexafluorophosphate was used as the AP substrate. This anionic substrate (S-) is enzymatically transformed at pH 9.0 into a cationic phenol derivative (P+) which can be easily accumulated in the polyanionic Nafion coating and determined by cyclic voltammetry. During the enzyme reaction, the AP-associated beads were localized on the surface of the Nafion-SPE with the aid of a magnet, thus effectively increasing the concentration of P+ in the Nafion-modified electrode vicinity. The enzyme generation of P+ close to the electrode surface, and thereby to the Nafion film, resulted in a high amplification of the response. A detection limit of 0.01 microgram L-1 2,4-D was thus achieved. The performance of the sensor was successfully evaluated on river water samples spiked with 2,4-D, indicating that this convenient and sensitive technique offers great promise for decentralized environmental applications.

Highly Oriented, Self-Assembled Alkanephosphate Monolayers on Tantalum(V) Oxide Surfaces

Octadecyl phosphoric acid ester has been found to produce oriented, well-ordered monolayers on a flat tantalum(V) oxide surface, via self-assembly from a heptane/propan-2-ol solution. By means of contact angle, optical waveguide lightmode spectroscopy (OWLS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and X-ray photoelectron spectroscopy (XPS) measurements, it has been shown that these layers closely resemble those formed by the corresponding thiol−gold system, with respect to packing density, inclination, and order. The system shows promise as an approach to functionalizing oxide surfaces with well-ordered organic monolayers, with potential applications in the fields of biochemical analysis and sensors.

On the kinetics of rare-earth extraction into D2EHPA

Extraction kinetics of rare-earth elements (La 3+, Ce 3+, Pr 3+, Nd 3+, Eu 3+) in nitric acid, thiocyanate and formate into D2EHPA (bis-2-ethylhexyl phosphoric acid ester, 0.05 kmol m -3) is studied in a stirred cell at pH=2.1. Extraction rate is found to be limited by diffusion. Individual mass transfer coefficients remain consistent for the metal ions investigated within a given aqueous system but are found to be approximately 25% higher in the formate system than in others. An explanation can be given by coupled diffusion of cationic and anionic species.

Phosphorus-Containing Fungicides: a Review of Current Research and Prospects

Two main types of phosphorus-containing compound are currently under investigation as potential fungicides: (a) esters of phosphoric, phosphorothioic, phosphorodithoic, or alkyl-phosphonic acids, including examples containing terpenoid or heterocyclic structures, and (b) aminophosphonic or aminophosphinic acids and their derivatives. The latter types are especially attractive environmentally but none has yet been commercialised.

Metallomicelles Made of Ni(II) Complexes of Lipophilic 2-Pyridineketoximes as Powerful Catalysts of the Cleavage of Carboxylic Acid Esters

A series of 2-pyridineketoximes with paraffinic chains of different lengths (CH 3 , 1a; C 8 H 17 , 1b; C 13 H 27 , 1c) has been synthesized, and their complexes with Cu(II), Co(II), Zn(II), and Ni(II) have been investigated in the cleavage of p-nitrophenyl esters of carboxylic and phosphoric acids in water (1a) or in comicelles with CTABr (1b,c). While the Co(II) and Cu(II) complexes are ineffective in promoting the cleavage of acetate (PNPA) and hexanoate (PNPH) esters, the Zn(II) and especially the Ni(II) complexes strongly accelerate the cleavage of such substrates. With the latter metal ion, the effective species is a complex with a 2:1 ligand/metal ion stoichiometry and a pK a of the oximic hydroxyl of approximately 5 and 3.7 in the absence and in the presence of CTABr, respectively. Strong evidence has been obtained concerning the mode of action which involves nucleophilic attack of the oximate function on the carbonyl carbon of the ester to give, as transient intermediate, the acylated oxime; its Ni(II)-mediated hydrolysis by water has also been investigated to better define the whole catalytic cycle. The system displays its highest efficiency at low pH values and in comicelles of CTABr: in the presence of 1b/Ni(II)/CTABr at pH 4 the observed rate enhancements are of over 5 orders of magnitude in the cleavage of PNPH and the system is truly catalytic with a sizable turnover rate. In comparison with the high reactivity toward carboxylic esters, the metal ion complexes of the ketoximes investigated are surprisingly ineffective in promoting the cleavage of p-nitrophenyl esters of diphenylphosphoric acid (PNPDPP).