Phenyl Phosphite Research Articles

Synthesis of biocompatible BSA-GMA and two-photon polymerization of 3D hydrogels with free radical type I photoinitiator.

Although the development of three-dimensional (3D) printing technology is growing rapidly in the biomedical field, it remains a challenge to achieve arbitrary 3D structures with high resolution and high efficiency. Protein hydrogels fabricated by two- photon polymerization (TPP) have excellent mechanical properties, high precision, and 3D architecture. However, a large number of the amino acid group in bovine serum albumin (BSA) would be consumed when the protein-based hydrogels use dyes of free radical type II photoinitiators. In this study, we use glycidyl methacrylate (GMA) to modify BSA molecules to obtain a series of BSA-GMA materials, allowing the protein material to be two-photon polymerized with a water-soluble free radical type I photoinitiator. The precisely controllable 3D structure of the BSA-GMA hydrogel was fabricated by adjusting the concentration of the precursor solution, the degree of methacrylation, and the processing parameters of the TPP technique. Importantly, BSA-GMA materials are free of acidic hazardous substances. Meanwhile, the water-soluble initiator lithium phenyl (2,4,6-trimethylbenzoyl) phosphite (LAP) allows TPP on the vinyl group of the GMA chain and thus without consuming its amino acid group. The as-prepared BSA-GMA hydrogel structure exhibits excellent autofluorescence imaging, pH responsiveness, and biocompatibility, which would provide new avenues for potential applications in tissue engineering and biomedical fields to meet specific biological requirements.

Evaluation of the thermal stabilization behavior of hydrotalcite against organic stabilizers for plasticized PVC films

This study focuses on the systematic comparison of the thermal stabilization behavior of the hydrotalcite which is present in the nature and is non-toxic, with organic stabilizers (mixed metal salts, maleimide and tri-nonyl phenyl phosphite) having high stabilizing efficiency. For the purpose of this study, first plastisols were prepared by mixing plasticizer and thermal stabilizers into the PVC resin. Then films were obtained from plastisols, which were applied on a glass plate as 150μ thick films with the help of a film applicator. The films were cured for 15 min in oven at 160 °C to produce plastigel films. The stabilization behavior of these films was measured by applying various stabilization testing methods: thermal aging test, oxidation index, polyene formation measurement and discoloration. Thermal aging studies for these plastigel films were carried out at 100 and 150 °C up to 420 min. Oxidation index values are associated with oxidized surface layer that is formed after the aging and degradation of the films, which are determined by FTIR spectroscopy. Thermal stability behavior in terms of concentration of polyenes formed due to the released HCl has been investigated by UV–visible spectroscopy. Color changes of the degraded films were followed by observed colorimetry. According to the results, number of the polyenes for all degraded films increased with increasing time and temperature. The results have proved the greater stabilizing efficiency of hydrotalcite relative to that of the thermal stabilizers in terms of the number of the conjugated double bond, polyene concentration, polyene formation rate and change in color. It is believed that the results will contribute to the thermal stability of PVC by different stabilizers and blends, and an effort has been made in this article to throw light on this issue.

SYNTHESIS AND REACTION KINETICS STUDY OF TRI PHENYL PHOSPHITE

SYNTHESIS AND REACTION KINETICS STUDY OF TRI PHENYL PHOSPHITE

Lamivudine phosphoramidates. Unexpected products of a well-known reaction

A series of phosphoramidate derivatives of β-L-2´,3´-dideoxy-3´-thiacytidine (lamivudine, 3TC), which are the latent forms of 3TC monophosphate, were synthesized. An optimal synthetic pathway towards these compounds involves synthesis of phosphoramidates from diphenyl phosphite followed by treating the resulting 3TC phenyl phosphite with tetrachloromethane and different amines. Surprisingly, this reaction sequence produces two groups of products, 3TC phenyl phosphoramidates (4) and bis-3TC-phosphoramidates (5). Synthesis of compounds 5 has not been previously described.

Phthalates and Other Plastic Additives in Surface Sediments of the Cross River System, S.E. Niger Delta, Nigeria: Environmental Implication

Quantitative determination of phthalates and other plastic additives was carried out using GC-MS in order to understand the distribution and fate of these compounds in surface sediments of the Cross River System. Results show the concentration ranges (mean±standard deviation) of the three phthalates as: di(ethylhexyl)phthalate (DEHP; 1.97– 86.76 [24.06 ± 29.88 mg/kg dry weight dw]); di(n-butyl)phthalate (DnBP; 0.16 – 17.41 [3.25 ± 5.03 mg/kg dw]); di(isobutyl)phthalate (DiBP; 1.14 – 29.64 [9.82 ± 10.23 mg/kg dw]). However, examination of n-hexane procedural blank (used also in the study for clean-up protocol) GC trace revealed the presence of certain amounts of DEHP and tris-2,6-di(t-butyl)phenylphosphite (PhP) which interfere with the targeted analytes. Therefore, extract/blank (E/B) ratios were calculated and were in the range 1.05 – 12.54, indicating that the concentrations of DEHP and PhP previously assigned to the sediments were partly derived from laboratory artifacts. Differences in grain size distribution, partitioning behavior, volatility and solubility in the aqueous phase as well as localized influx may account for the observed spatial variation of phthalates and other plastic additives in the river system. The primary sources of these phthalates and tris-2,6-di(t-butyl)phenylphosphate (PhP’) were considered to be the result of direct discharge of untreated effluent/solid waste and emission arising from burning of refuse containing plastic materials, respectively. The occurrence of certain anti-oxidant degradation products in sediments (not in the blank) such as 2,6-di(t-butyl)-4-hydroxybenzaldehyde (HBA) and 2,6-di(t-butyl)quinine (Qn) and PhP’ (a compound proposed here as a possible marker for plastic combustion for the region/air basin), suggests that phthalates contamination had occurred before sample contact with laboratory artifacts.

Synthesis and Characterization of Tris (nonyl) Phenyl Phosphite and Interfacial Study with Karanja Oil in Acetonitrile Solution

Tris (nonyl) phenyl phosphite is a triarylphosphite. It is obtained when nonylphenol reacts with the phosphorus trichloride. The reaction between nonylphenol and phosphorus trichloride is a nonelementary reaction, an intermediate of this reaction is stable and greatly affects the yield of tris (nonyl) phenyl phosphite. Phosphorus trichloride has three chlorine atoms and it replaces one by one with nonylphenol. This reaction mechanism is a series parallel. It is in series with respect to phosphorus trichloride (PCl3) and parallel with respect to nonyl phenol. The reaction between PCl3 and nonylphenolis is highly exothermic reaction. Therefore, to avoid run away conditions and to control the heat of the reaction, PCl3 is required to be added in a controlled manner. The interfacial tension (IFT) of tris (nonyl) phenyl phosphite/Karanja oilin acetonitrile solution was measured by an interfacial tensiometer (Model Kruus K-100). The critical micelle concentration (CMC) and interfacial tension at CMC (γcmc) were calculated.

Preparation of New Series of Poly(amide-imide) Reinforced Layer Silicate Nanocomposite Containing N-Trimellitimide-L-Alanine

A new poly(amide-imide)-montmorillonite series were gen- erated through solution intercalation technique. Cloisite ® 20A was used as a modified montmorillonite for ample compatibility with the poly(amide-imide) (PAI) matrix. The PAI 5 chains were synthesized by the direct polycondensation reaction of N-trimellitylimido-L-ala- nine (3) with 4,4'-diamino diphenyl ether (4) in the presence of tri- phenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nanocomposite films 5a-5d with (5-20 Wt%) silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocompos-

Gas chromatographic technique for determination of Irgafos 168 in polyolefin samples after conversion to the related phenolic compound by saponification

A gas chromatographic technique is reported for the determination of a secondary antioxidant, Irgafos 168, in polymeric samples. Irgafos 168 [tris(2,4-di-tert-butyl phenyl)phosphite] is extracted by dissolution/precipitation, saponified to 2,4-di-tert-butyl phenol by refluxing in the presence of methanolic potassium hydroxide, and determined by gas chromatography-flame ionization detection. The method’s repeatability is good, and the relative standard deviation is 7.5% (between runs) and 15.5% (between days). This method was applied to the determination of Irgafos 168 in commercial polymers, and the obtained results were in relatively good agreement with those obtained by the previously reported spectrophotometric method.

Design of Ionic Phosphites for Catalytic Hydrocyanation Reaction of 3‐Pentenenitrile in Ionic Liquids†

AbstractThe synthesis and characterization of a novel class of ionic phosphites bearing either a single cationic group obtained by quaternization of aminophosphites or three cationic groups prepared by reaction of phosphorus trichloride with imidazolium phenols are reported. The catalytic hydrocyanation reaction of 3‐pentenenitrile (3PN) into adiponitrile has been performed in the presence of Ni(0) with ionic phosphite ligands, and a Lewis acid in biphasic ionic liquid/organic solvent system. The screening of several original cationic phosphites was performed and the experimental conditions were optimized for the tri‐cationic phosphite tris‐4‐[(2,3‐dimethylimidazol‐1‐yl)methyl]phenyl phosphite tris[bis(trifluoromethylsulfonyl)amide]. It is possible to obtain performance similar to molecular systems and the catalyst and the Lewis acid were immobilized in the ionic phase.

Reactions of 1,2-Imino Alcohols with Phosphoromonochloridites: Formation of 2-Iminoalkyl(phenyl) phosphites

1,2-Imino alcohols existing in a tautomeric equilibrium with the corresponding 1,3-oxazolidines react with phosphoromonochloridites in ether in the presence of triethylamine to form 2-iminoalkyl(phenyl) phosphites as the only reaction products.

An ab initio and AIM study on the decomposition of phosphite ozonides

DFT calculations at the Becke3PW91/6–31+G(d) level of theory provided optimized geometries, transition states, and wave functions suitable for the study of the reactivity and molecular structure with Atoms-in-molecules (AIM) of phosphite ozonide complexes. These calculations also provided activation energies for the extrusion of singlet oxygen from the ozonides, which occurs in a concerted manner. The molecular species investigated were trimethyl phosphite ozonide (1), triphenyl phosphite ozonide (2), trifluoromethyl phosphite ozonide (3), trifluoroethyl phosphite ozonide (4), 4-ethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane ozonide (5), 1-phospha-2,6,7-trioxabicyclo[2.2.2]octane ozonide (6), 1-phospha-2,8,9-trioxadamantane ozonide (7), and propylene phenyl phosphite ozonide (8). Single-point calculations at the Becke3PW91/6–311++G(d,p) level on the geometries obtained from the lower level theory yielded activation energies of 15.1 and 16.4 kcal mol–1 for the nonconstrained complexes 1 and 2, respectively. These values differed from the electronegative trifluoro derivatives 3 and 4, which had much higher barriers of 23.5 and 20.8 kcal mol–1, respectively. The activation energies of the bicyclic complexes 5–7 were significantly higher than 1 and 2 and comparable to 3 and 4, ranging from 23 to 26 kcal mol–1. An intermediate barrier of 20.5 kcal mol–1 was computed for 8. AIMPAC studies showed no direct correlation between the AIM atomic charges on the phosphorus or oxygen atoms of the ozonide ring with the ease of decomposition of 1–8 to singlet oxygen and the corresponding phosphate.Key words: phosphite ozonide complexes, decomposition, DFT methods, AIM, activation energy.

Effect of vulcanization systems and antioxidants on discoloration and degradation of natural rubber latex thread under UV radiation

The effect of accelerator combinations and antioxidants on UV radiation degradation of natural rubber (NR) latex thread with a conventional and efficient vulcanization system is presented. Zinc diethyl dithiocarbamate (ZDEC), zinc dibutyl dithiocarbamate (ZDBC), zinc mercaptobenzothiazole (ZMBT), and tetramethyl thiuram disulfide (TMTD) were used as accelerators. The antioxidants used were reaction products of butylated p-cresol and dicyclopentadiene (Wingstay-L), Tris-nonylated phenyl phosphite (Crystol EPR 3400), styrenated phenol (SP), and polymerized 1,2-dihydro 2,2,4-trimethyl quinoline (HS). The thread samples were exposed to UV radiation and the appearance and physical properties of the thread were examined. The results indicated that the threads having ZDBC + ZDEC and ZDBC + ZMBT combinations as accelerators are more resistant to UV radiation than the thread having the ZDEC + ZMBT combination. The antioxidants Wingstay-L and SP + HS are effective in retaining the physical properties of the thread after UV exposure, and Crystol EPR 3400 is better in reducing discoloration. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 304–310, 2000

Enantioselective allylic substitution catalyzed by an iridium complex: remarkable effects of the counter cation

Allylic substitution of a methyl carbonate of cinnamyl alcohol with the anion of dimethyl malonate gave the branched olefin with high enantioselectivity in the presence of (S)-1,1′-binaphthyl-2,2′-diyl phenyl phosphite when a combination of lithium and zinc was used as counter cation.

ChemInform Abstract: Synthesis and Conformational Analysis of Six‐Membered Cyclic Phenyl Phosphites.

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.

Synthesis and Conformational Analysis of Six-Membered Cyclic Phenyl Phosphites

Synthesis and Conformational Analysis of Six-Membered Cyclic Phenyl Phosphites

Degradability testing of radiation‐vulcanized natural rubber latex films

AbstractThe degradability under various conditions of five kinds of radiation‐vulcanized natural rubber latex (RVNRL) films was studied. The treatments were leaching in methanol, leaching in 1% ammonia solution, mixing with tris(nonylated phenyl)phosphite (TNP) antioxidant, blending with poly(methyl methacrylate) (PMMA), and grafting with PMMA, Comparisons were made with sulfur‐vulcanized natural rubber latex (SVNRL) film. RVNRL films SVNRL film can be kept for a long time when indirectly exposed to sunlight at room temperature. However, the former degraded much more rapidly than did the latter. TNP was found to be very suitable as an antioxidant to prolong the life of RVNRL films under dry conditions. PMMA, either blended or grafted with RVNRL, was ineffective in the prevention of deterioration of RVNRL films. The rapid degradation of RVNRL products could be an advantage over SVNRL products in environmental and wildlife conservation. © 1994 John Wiley & Sons, Inc.

Stabilization of radiation-vulcanized SBR against thermal oxidation

The effect of different antioxidant compounds and their mixture on the thermal oxidation behaviour of electron-beam-irradiated styrene-butadiene rubber (SBR) has been investigated. The compounds used were N-(1,3-dimethyl-butyl) N′-phenyl- p-phenylenediamine ( I); 4,4′-thiobis(6- tert-butyl- m-cresol) ( II); nickel dibutyl dithiocarbamate ( III); trisnonyl phenyl phosphite ( IV) and 2-mercapto-benzimidazol ( V), and mixtures of ( I and III), ( I and IV), ( II and III) and ( II and IV). The thermal oxidation response was evaluated by measurement of the percentage retention of tensile strength and ultimate elongation of the EB-irradiated SBR samples after they had been thermally aged in air at 100°C for up to 14 days. The results indicate a remarkable antioxidant efficiency of ( V) for SBR compared to either the other single antioxidants or their mixtures. The high efficiency of ( V) may be attributed to its main function as a preventive peroxide decomposer. The labile hydrogen attached to the nitrogen atom may also act in chain breaking. Also, the possibility exists that at least a small degree of linking occurs during compounding and vulcanization via the saturation of the double bonds of butadiene units by antioxidants or via the macro alkyl radicals, produced from the interaction of polymer and hydroperoxide, and thiyl radicals of the antioxidant.

Efficiency of processing stabilizers using a micro-oxygen uptake technique

The thermooxidative stability of various low density polyethylene (LDPE) film formulations was investigated using the technique of micro oxygen uptake measurement following multiple extrusions. The results show that the micro oxygen uptake technique is more sensitive than conventional test methods. High molecular weight hindered phenolic stabilizers are more effective in reducing gel formation during polymer film production than are lower molecular weight species such as butylated hydroxytoluene (BHT). The antioxidant 2,2′-ethylidene-bis-(4,6-di-tert-butylphenol) is an effective stabilizer, but it forms a highly coloured complex with transition metal impurities. The hindered phenol/organic phosphite system, comprising a combination of 0.008% (wt/wt) octadecyl-3-(3,5-di-tert-butyl)-4-hydroxy-phenol propionate and 0.032% (wt/wt) tris-(2,4-di-tert-butyl)phenyl phosphite, is effective in suppressing the formation of coloured products but does not provide adequate thermal stability.

Organophosphorus antioxidants—VIII. Kinetics and mechanism of the reaction of organic phosphites with peroxyl radicals

Trialkyl phosphites react with cyanoisopropylperoxyl radicals, generated by thermolysis of azobis(isobutyronitrile) in the presence of oxygen, to give the corresponding phosphates with rate constants of the order of 10 3 M −1 sec −1 at 65°C. Phenyl phosphites are oxidized also. A small amount of cyanoisopropyl phosphite is formed by substitution of the phosphite by alkyloxyl radicals leading to phenoxyl radicals. Sterically hindered aryl phosphites react with cyanoisopropylperoxyl radicals to yield the corresponding phosphates and alkoxyl radicals which in a second step react with phosphite by substitution releasing a sterically hindered phenoxyl radical. Therefore, sterically hindered phosphites are capable of acting as chain-terminating primary antioxidants. Because the rate constants of reaction of these phosphites with peroxyl radicals are only in the range of 10 2 M −1 sec −1 and 100 times smaller than those of phenols, phosphites should be less active as primary antioxidants than phenols.

Reaktionen trivalenter Phosphorverbindungen mit tert‐Butoxylradikalen

AbstractThe products of the reaction of several alkyl, aryl, sterically hindered aryl and cyclic phosphites, thiophosphites, benzenephosphonites and triphenylphosphine with tert‐butoxyl radicals generated by thermolysis of di‐tert‐butyl peroxalate (DTBPO) in chlorobenzene at 50°C was studied.Alkyl phosphites are oxidized to the corresponding phosphates by β‐scission of the intermediate phosphoranyl radicals. Phenyl phosphites react under displacement of a phenoxyl to give tert‐butyl phosphites by α‐scission of the intermediate phosphoranyl radicals. Sterically hindered p‐methyl‐phenyl phosphites also form the tert‐butyl phosphites accompanied by rearranged p‐hydroxyphenylmethanephosphonates. Cyclic arylene phosphites are predominantly oxidized, substitution takes place to a minor extent.Benzenephosphonites and phosphines react with tert‐butoxyl radicals by oxidation to give the corresponding phosphonates and phosphine oxide, resp.Those phosphorus compounds which are oxidized with the formation of tert‐butyl radicals accelerate the thermal decomposition of DT BPO under the condition studied.