Phosphoric Acid Diesters Research Articles

Conducting blends of polyaniline with conventional polymers

Phosphoric acid diesters effectively protonate polyaniline and simultaneously plasticize it. This plasticized polyaniline can be processed either by thermal methods or from solution. It can serve, therefore, as a conducting additive to common polymers, such as poly(vinyl chloride), polystyrene, poly(methyl methacrylate) and cellulose derivatives. In each case only few wt. % of polyaniline is needed to render a conductive blend. Microprobe studies and scanning electron microscopy show uniform distribution of polyaniline/diester in the polymer matrix. The conductivity of the blends ranges between 10 −2and 10 S/cm, and the mechanical properties are those of the non-conducting matrix. Thermally processable blends of PVC, having very good mechanical properties, were prepared by mechanical mixing with plasticized polyaniline, while those of PMMA, PS or cellulose derivatives were cast from solutions.

Dimerization constants for phosphoric acid diesters

Phosphoric acid diesters are found to dimerize in dry chloroform with dimerization constants of 10 4 to 10 5 M −1. A correlation between dimerization constants and Hammett sigma values exists.

Solid-liquid distribution studies of divalent metals from nitrate media using impregnated resins containing a bifunctional organophosphorous extractant ( O-methyl-dihexyl-phosphine-oxide O′-hexyl-2-ethyl phosphoric acid)

The present paper presents the results of the extraction of Zn(II), Cu(II) and Cd(II) from 0.1 M NaN0 3 at 25°C by impregnated resins containing a bifunctional extractant, incorporating phosphine oxide and phosphoric acid diester funcionalities, O-methyl-dihexyI-phosphine-oxide O′-hexyl-2-ethyl phosphoric acid (HL). Solvent impregnated resins have been prepared by direct adsorption of HL into the styrene/divinylbenzene macroporous support, Amberlite XAD2, by using the dry impregnation method. The adsorption of HL, on the styrene/divinylbenzene macroporous support is shown by FTIR spectroscopy to be the result of only weak extractant-support interactions. The distribution coefficient of Zn(II), Cu(II) and Cd(II) was determined as a function of pH and extractant (HL) concentration in the resin phase and the data were analyzed graphically using the slope analysis method and numerically using the program LETAGROP-DISTR. The composition of the extracted species in the resin phase has been determined. Analysis of the results showed that the extraction of these metal ions can be explained assuming the formation of metal complexes in the resin phase with a general composition ML, (N0 3) t (HL) q where p, t, q take different values depending on the metal. An extraction reaction is proposed and the extraction constants of these species are given.

Stereoselective Synthesis of α-L-Rhamnopyranosyl Phosphonates via α-L-Rhamnopyranosyl Trifluoroacetate

Abstract α-L-Rhamnopyranosyl phosphates 8a-b∼12a-b were obtained in high yield and high stereoselectivity from α-L-rhamnopyranosyl trifluoroacetate 2a-b and phosphoric acid diesters in the presence of a Lewis acid.

Phosphoric acid diesters protonated polyaniline: Preparation, spectroscopic properties, and processability

AbstractAliphatic and aromatic diesters of phosphoric acid were tested as dopants improving pro‐cessability of polyaniline (PANI) in its doped (conducting) state. It has been found that both aromatic and aliphatic diesters effectively protonate polyaniline, inducing at the same time its solubility. The protonated state has been confirmed by three independent spec‐troscopic methods (FTIR, Raman, and UV‐vis‐NIR). Both aromatic and aliphatic diesters of phosphoric acid plasticize polyaniline which, in turn, allows for the preparation of highly conducting films of PANI or highly conducting blends of PANI with classical nonconducting polymers by thermal processing. © 1995 John Wiley & Sons, Inc.

Thermally processable conducting polyaniline

Protonation of polyemeraldine base with aryl phosphoric acid diesters have been studied with the main goal to obtain thermally processable conducting polymers. Polyaniline protonated with aryl diesters exhibits excellent thermal properties. Since diesters plasticize polyaniline in addition to its protonation conductive blends of PANI and plasticized PVC with low (ca. 6 wt%) percolation threshold can be prepared by hot pressing.

Supramolekulare Phosphorylierung kationischer Alkohole mit 3‐Arylindol‐4‐carboxamidin‐Struktur

Supramolecular Phosphorylation of Cationic Alcohols with a 3‐Arylindole‐4‐carboxamidine FrameworkRecently we reported on the synthesis of 8‐phenylnaphthalene‐1‐carboxamidines equipped with nucleophilic side chains (1, 2). In the protonated state these compounds were able to coordinate phosphoric acid diesters as ion‐pair complexes and to react with them in a quasi‐intramolecular way. In comparison with noncharged alcohols high‐rate enhancements of phosphorylation could be achieved. Now we describe the synthesis of analogous amidinium alcohols constructed from a 3,4‐disubstituted indole framework. Due to the five‐membered ring of the indole the angle between the substituents of 4 and 5 is extended compared to the naphthalene derivatives 1 and 2. As a result from this structural change a slight increase of the phosphorylation rate of 4 is observed.

ChemInform Abstract: Synthesis of Phosphoric Acid Diesters of 7β‐Hydroxycholesterol and of Carbohydrates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Complexation of Phosphoric Acid Diesters with Polyaza-Clefts in Chloroform: Effects of Phosphodiester Dimerization, Changing Cavity Size, and Preorganizing Amine Recognition Units

Complexation of Phosphoric Acid Diesters with Polyaza-Clefts in Chloroform: Effects of Phosphodiester Dimerization, Changing Cavity Size, and Preorganizing Amine Recognition Units

Moenomycin-type transglycosylase inhibitors: Inhibiting activity vs. topology around the phosphoric acid diester group

The correct configuration at C-1 of the uronamide carrying the phosphate group is essential for antibiotic activity.

Das trans‐decalingerüst als Abstandshalter für axial konfigurierte Diamine: Herstellung eines phosphatbindenden Bis(guanidins)

trans‐Decalin as a Spacer for Axially Configurated Diamines: Preparation of a Phosphate Binding Bis(guanidinium) CompoundA new type of bis(guanidinium) compound 2 is described which was prepared from trans‐decalin spacers bearing nitrogen substituents in axial positions. Starting from 2, 7‐dimethoxynaphthalene, a sequence of three Birch reductions produced gram amounts of the saturated intermediate and established the stereochemistry of the decalin framework. Guanidinium salt 2a turned out to be a good receptor molecule for phosphoric acid diester anions. However, the catalytical influence on phosphoryl transfer reactions is only weak. magnified image

Beschleunigung von Substitutionsreaktionen eines Phosphorsäurediesters durch Bis(guanidinium)‐Verbindungen

Acceleration of Substitution Reactions of a Phosphoric Acid Diester by Bis(guanidinium) CompoundsIon‐pair coordination of phosphoric acid diesters with positively charged guanidines may cause large rate accelerations in substitution reactions. Here we present a comparative study on the catalytical influence of several mono‐ bis‐ and tris(guanidines) and of other cationic compounds. Large rate effects occur if 1,3‐bis(aminomethyl)benzene or 1,2‐ethylenediamine are used as spacers. Further acceleration can be achieved by exchanging guanidinium groups by 2‐aminoimidazolines. The 4800‐fold rate enhancement seen in the best case demonstrates the importance of the bis(guanidinium) moiety of staphylococcal nuclease and gives good perspectives towards future uses of guanidinium compounds as RNA cleaving agents. magnified image

Synthesis of phosphoric acid diesters of 7β- hydroxycholesterol and of carbohydrates

In order to enhance the antitumor efficacy of 7β-hydroxycholesterol by targetting its action to defined organs, the phosphoric acid esters of 3(7β-hydroxycholesteryl) and of 6(galactopyranosyl) 1 or 6(mannopyranosyl) 2 were synthesized by the phosphoramidite method (with protected C-1, 2, 3, 4 hydroxyl groups for the carbohydrates). As the protection of the sugars increased the length of the synthesis, we decided to use the hydrogen-phosphonate methodology which leads to a selective phosphorylation at the primary alcohol of carbohydrates and avoids the use of protected carbohydrates. Compound 2 was synthesized in good yield. However compound 1, probably due to steric hindrance, could not be obtained by this second method.

Stability studies on L-ascorbic acid dl-alpha-tocopherol phosphoric acid diester potassium salt (EPC-K)

A compound having structures of both vitamins E and C, L-ascorbic acid dl-alpha-tocopherol phosphoric acid diester potassium salt (EPC-K), which was proven to have both anti-oxidative3%!d moisturizing effects, has been formulated in the quasi drug hair growing products to mainly prevent dandruff and itching which may be one of the causes for the hair loss. Stabilities of EPC-K in 75% ethanolic solutions with various pHs (2-10) were examined extensively by storing them at 50 degrees C for 30 d and by sunlight exposure for 30 d. Decomposition of EPC-K was only observed under pH 2 at a level of 50% and under sunlight exposure at 25% level. A main decomposition product was identified as tocopheryl phosphate (EP), suggesting that a decomposition route was through hydrolysis. EPC-K was found to decompose by as much as 20% under 30 d storage at 50 degrees C when the concentration of the aqueous ethanolic solution was 0-30%. 1H, 13C and 31P-NMR studies in addition to a micelle formation test using pyrene fluorescent probe revealed that EPC-K formed a micelle at such low concentration of ethanol, which was assumed to be a cause for unstableness of EPC-K in that range. Hydrolytic decomposition of EPC-K was found by the reaction rate study to be a pseudo first order reaction with activation energy of 16.98 kcal/mol.

Catalysis of the Hydrolysis of Phosphoric Acid Diesters by Lanthanide Ions and the Influence of Ligands

Catalysis of the Hydrolysis of Phosphoric Acid Diesters by Lanthanide Ions and the Influence of Ligands

Processable conducting polymers obtained via protonation of polyaniline with phosphoric acid esters

The protonation of polyemeraldine base (PANI) by diesters of phosphoric acid was studied. Three esters were investigated, namely bis(2-methylpropyl) hydrogen phosphate (DiBHP), bis(2-ethylhexyl) hydrogen phosphate (DiOHP) and its non-branched analogue, bis(n-octyl) hydrogen phosphate (DnOHP). It has been found that DiOHP, in addition to protonation, plasticizes PANI at very low ester contents i.e. for y≥0.25 in PANI(DiOHP) y. In PANI(DnOHP) y and PANI(DiBHP) y the plastification starts at y=0.50 and y=0.65 respectively. It is clear that the long and branched substituents facilitate plastification. PANI protonated with DiOHP is soluble in common organic solvents such as toluene, chloroform, THF etc. The soluble fraction is enriched in DiOHP as compared with the parent protonated polymer. The existence of the anions originating from the ester in the soluble part of the polymer was confirmed by FTi.r. and 31P n.m.r. studies of the soluble fraction. Free-standing films with a conductivity of 10 S cm −1 can be produced by hot pressing PANI(DiOHP) y at temperatures of 80–140°C. At higher temperatures partial degradation of the complex occurs resulting in a decrease of conductivity with a simultaneous increase of Young's modulus and tensile strength. Blends of DiOHP-plasticized PANI and dioctyl phthalate-plasticized PVC, of excellent mechanical properties, can be prepared by hot pressing at 160°C.

Processable conducting polyaniline

It has been found that diesters of phosphoric acid with branched alkyl substituents solubilize polyaniline in its protonated (conducting) state. Polyaniline protonated with bis(2-ethylhexyl)phosphate or bis(2-methylpropyl)phosphate is highly soluble in common organic solvents such as toluene, decaline, THF and chlorinated hydrocarbons. Conducting blends with poly(methylmethacrylate) or poly(acylonitrile-butadiene-styrene) (ABS) can be prepared showing high conductivity for very low electroactive component content. Protonation of polyemeraldine base with neat esters results in a heavily plastisized mixture which can be thermally processed to give free standing films with conductivities exceeding 10 S/cm. Depending on the content of the protonating agent, time and temperature of pressing films with different Young modulus, tensile strength and elongation at break can be prepared. Similarly, conducting blends with excellent mechanical properties can be prepared from diester plasticized polyaniline and plasticized polyvinyl chloride.

Strand breakage in poly(C), poly(A), single- and double-stranded DNA induced by nanosecond laser excitation at 193 nm.

Single- and double-stranded calf thymus DNA and two polynucleotides (0.4 mM) were studied in aqueous solution at pH approximately 7 using pulsed, 20 ns laser excitation at 193 nm. Monophotonic ionization of the nucleic acids is suggested from the linear dependences of the concentration of ejected electrons and the number of single- and double-strand breaks (ssb, dsb, respectively) on laser intensity (IL) in the range (0.2-3) x 10(6) W cm-2. The quantum yields of formation of hydrated electrons (phi e-) and ssb and dsb (phi ssb and phi dsb) are therefore independent of IL. In contrast, under 248 nm excitation these quantum yields increase linearly with IL under otherwise comparable conditions. Nevertheless, several effects and mechanistic implications are analogous using lambda exc = 193 and 248 nm. For polycytidylic acid, poly(C), in Ar-saturated solution for example, the efficiency of ssb per radical cation (eta RC = phi ssb/phi e-) is similar to the efficiency of ssb per OH radical (eta OH). For polyadenylic acid, poly(A), and single- and double-stranded DNA eta RC (lambda exc = 193 nm) is significantly smaller than eta OH. The ratio phi ssb (N2O)/phi ssb (Ar) is approximately 2 for poly(C), approximately 4 for poly(A) approximately 10 for DNA; the conversion of hydrated electrons into OH radicals in N2O-saturated solution and smaller eta RC than eta OH values in the case of DNA account for these results. For double-stranded DNA phi dsb does not depend on IL but increases linearly with the dose, indicating an accumulative effect of two ssb to generate one dsb. The critical distance for this event is 60-85 phosphoric acid diester bonds.

SINGLE‐ and DOUBLE‐STRAND BREAK FORMATION IN DOUBLE‐STRANDED DNA UPON NANOSECOND LASER‐INDUCED PHOTOIONIZATION

Double-stranded (ds) calf thymus DNA (0.4 mM), excited by 20 ns laser pulses at 248 nm, was studied in deoxygenated aqueous solution at room temperature and pH 6.7 in the presence of a sodium salt (10 mM). The quantum yields for the formation of hydrated electrons (phi c-), single-strand breaks (phi ssb) and double-strand breaks (phi dsb) were determined for various laser pulse intensities (IL). phi c- and phi ssb increase linearly with increasing IL; however, phi ssb has a tendency to reach saturation at high IL (greater than 5 X 10(6) Wcm-2). The ratio phi ssb/phi c-, representing the number of ssb per radical cation, is about 0.08 at IL less than or equal to 5 X 10(6) Wcm-2. For comparison, the number of ssb per OH radical reacting with dsDNA is 0.22. On going from argon to N2O saturation, phi ssb and phi dsb become larger by factors of approximately 5 and 10-15, respectively. This enhancement is produced by attack on DNA bases by OH radicals generated by N2O-scavenging of the photoelectrons. While phi ssb is essentially independent of the dose (Etot), phi dsb depends linearly on Etot in both argon- and N2O-saturated solutions. The linear dependence of phi dsb implies a square dependence of the number of dsb on Etot. This portion of dsb formation is explained by the occurrence of two random ssb, generated within a critical distance (h) in opposite strands. For both argon- and N2O-saturated solutions h was found to be of the order of 40-70 phosphoric acid diester bonds. On addition of electron scavengers such as 2-chloroethanol (or N2O plus t-butanol), phi dsb is similar to that in neat, argon-saturated solutions. Thus, hydrated electrons are not involved in the chemical pathway leading to laser-pulse-induced dsb of DNA.

A New Approach to P-C Bond Formation by Using Tri-Methylsilyl Phosphites

Abstract The in situ silylation of phosphorous acid diesters to phosphorous acid triesters by hexamethyldisilazane and trimethylsilyl halides under conditions of Michaelis-Arbuzov reaction was found as an efficient and facile reaction principle for P-C bond formation. In general the method can be applied also to Michaelis-Arbuzov reactions of phosphonous and hypophosphorous acid esters, to Tavs reaction of phosphorous and phosphonous acid esters as well as to photochemical conversions of arylhalides with trimethylsilyl phosphites. In any case described the observed yield is nearly quantitative.