Anhydride Form Research Articles

무수말레인산으로 그라프트된 폴리에틸렌 왁스의 중합과 가수분해에 대한 연구

In this study, Polyethylene wax, which was produced in manufacturing process of high density polyethylene was grafted with maleic anhydride (MAH). The influences of reaction parameters on the graft polymerization as well as the effect of hydrolysis of the anhydride functions were investigated. The results show that the grafting degree increased and conversion of maleic anhydride decreased with an increase in MAH monomer content. This means the highest grafting efficiency for the reaction can be met when MAH monomer content is about 15 wt%. DCP (dicumyl peroxide) and DTBP (di-tert-butyl peroxide) have been used as the initiator and the highest yield of grafting was obtained when the initiator content is about 0.5 wt%. However, It can be seen that the gel content values of this polyethylene wax grafted MAH were below 2%. It was also observed that the grafting degree increased with an increase in reaction temperature and the maximum value was reached 2 hours later. Although MAH functions grafted onto polyethylene wax were mainly in the carboxylic acid forms, some anhydride form of MAH appeared in over 5% of grafting degree. As a result of hydrolysis reaction, it was observed that the conversion of anhydride group into carboxylic acid group was reached up to 10%.

Condensation of 5-amino-4-arylpyrazoles with itaconic acid and maleic anhydride

Substituted 5-amino-4-arylpyrazoles on condensation with itaconic acid form substituted tetrahydropyrazolo[1,5-a]pyrimidines, and on condensation with maleic anhydride form 2,3-dihydro-1H-imidazolo[1,2-b]pyrazoles, which on more extended heating rearrange into tetrahydro-pyrazolo[1,5-a]pyrimidines.

Degradation of Perfluorosulfonic Acid Membrane Water Permeance via Formation of Sulfonic Acid Anhydrides

Six perfluorosulfonic acid (PFSA) membranes were subjected to hygrothermal aging at 95 {degree sign}C and monitored by FTIR to assess the rates and extent of ionomer cross linking to the sulfonic anhydride form. Anhydride formation was observed to occur for all PFSA membrane structures studied. The rates of transformation were found to be strong functions of relative humidity, air flow and membrane thickness. Several membrane properties including water permeance, conductivity, and IEC were correlated with the extent of the cross linking reaction.

A Dicarboxylic Fatty Acid Derivative of Paclitaxel for Albumin-Assisted Drug Delivery

Paclitaxel (PTX) is a potent chemotherapy for many cancers but it suffers from very poor solubility. Consequently, the TAXOL formulation uses copious amounts of the surfactant Cremophor EL to solubilize the drug for injection, resulting in severe hypersensitivity and neutropenia. In contrast to Cremophor EL, presented is a way to solubilize PTX by conjugation of a dicarboxylic fatty acid for specific binding to the ubiquitous protein, serum albumin. The conjugation chemistry was simplified to a single step using the activated anhydride form of 3-pentadecylglutaric (PDG) acid, which is reactive to a variety of nucleophiles. The PDG derivative is less cytotoxic than the parent compound and was found to slowly hydrolyze to PTX (≈ 5% over 72 h) in serum, tumor cytosol, and tumor tissue homogenate. When injected intravenously to tumor-bearing mice, [(3) H]-PTX in the TAXOL formulation was cleared rapidly with a half-life of 7 h. In the case of the PDG derivative of PTX, the drug is quickly distributed and approximately 20% of the injected dose remained in the vasculature experiencing a 23 h half-life. These improvements from modifying PTX with the PDG fatty acid present the opportunity for PDG to become a generic modification for the improvement of many therapeutics.

Solid‐state 11B and 13C NMR, IR, and X‐ray crystallographic characterization of selected arylboronic acids and their catechol cyclic esters

Nine arylboronic acids, seven arylboronic catechol cyclic esters, and two trimeric arylboronic anhydrides (boroxines) are investigated using (11)B solid-state NMR spectroscopy at three different magnetic field strengths (9.4, 11.7, and 21.1 T). Through the analysis of spectra of static and magic-angle spinning samples, the (11)B electric field gradient and chemical shift tensors are determined. The effects of relaxation anisotropy and nutation field strength on the (11)B NMR line shapes are investigated. Infrared spectroscopy was also used to help identify peaks in the NMR spectra as being due to the anhydride form in some of the arylboronic acid samples. Seven new X-ray crystallographic structures are reported. Calculations of the (11)B NMR parameters are performed using cluster model and periodic gauge-including projector-augmented wave (GIPAW) density functional theory (DFT) approaches, and the results are compared with the experimental values. Carbon-13 solid-state NMR experiments and spectral simulations are applied to determine the chemical shifts of the ipso carbons of the samples. One bond indirect (13)C-(11)B spin-spin (J) coupling constants are also measured experimentally and compared with calculated values. The (11)B/(10)B isotope effect on the (13)C chemical shift of the ipso carbons of arylboronic acids and their catechol esters, as well as residual dipolar coupling, is discussed. Overall, this combined X-ray, NMR, IR, and computational study provides valuable new insights into the relationship between NMR parameters and the structure of boronic acids and esters.

Biophysical Properties of Phenyl Succinic Acid Derivatised Hyaluronic Acid

Modification of hyaluronic acid (HA) with aryl succinic anhydrides results in new biomedical properties of HA as compared to non-modified HA, such as more efficient skin penetration, stronger binding to the skin, and the ability to blend with hydrophobic materials. In the present study, hyaluronic acid has been derivatised with the anhydride form of phenyl succinic acid (PheSA). The fluorescence of PheSA was efficiently quenched by the HA matrix. HA also acted as a singlet oxygen scavenger. Fluorescence lifetime(s) of PheSA in solution and when attached to the HA matrix has been monitored with ps resolved streak camera technology. Structural and fluorescence properties changes induced on HA-PheSA due to the presence of singlet oxygen were monitored using static light scattering (SLS), steady state fluorescence and ps time resolved fluorescence studies. SLS studies provided insight into the depolymerisation kinetics of PheSA derivatised HA matrix in the presence of singlet oxygen. Time resolved fluorescence studies grave insight into the dynamics of the reaction mechanisms induced on HA-PheSA by singlet oxygen. These studies provided insight into the medical relevance of PheSA derivatised HA: its capacity of scavenging singlet oxygen and of quenching PheSA fluorescence. These studies revealed that HA-PheSA is a strong quencher of electronic excited state PheSA and acts as a scavenger of singlet oxygen, thus medical applications of this derivatised form of HA may protect tissues and organs, such as skin, against reactive oxygen species damage.

Reaction of Finasteride Intermediate with Benzeneseleninic Anhydride: An In-Depth Study

One of the intermediates of finasteride was oxidized by the reaction of benzeneseleninic (BS) anhydride in refluxing toluene for 16 h. Sometimes, the desired product was obtained, and sometimes, there was no yield or very low yield at the end of the reaction time. To obtain a better understanding of such variations, laboratory syntheses were conducted with commercial BS anhydride, pure BS anhydride, pure BS acid, and mixtures of anhydride and acid samples. During the reaction, the intermediate reaction masses were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) at predetermined times and correlated with differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) samples. The DSC and XRPD data indicated that commercial BS anhydride samples did not always consist of the pure anhydride form. When the BS acid was present in the anhydride sample, the reaction rate was lower than that of the pure BS anhydride sample.

4-Mercaptophenylboronic Acid SAMs on Gold: Comparison with SAMs Derived from Thiophenol, 4-Mercaptophenol, and 4-Mercaptobenzoic Acid

We report the formation and characterization of self-assembled monolayers (SAMs) derived from the adsorption of 4-mercaptophenylboronic acid (MPBA) on gold. For comparison, SAMs derived from the adsorption of thiophenol (TP), 4-mercaptophenol (MP), and 4-mercaptobenzoic acid (MBA) were also examined. The structure and properties of the SAMs were evaluated by ellipsometry, contact-angle goniometry, polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). Specifically, ellipsometry was used to assess the formation of monolayer films, and contact angle measurements were used to determine the surface hydrophilicity and homogeneity. Separately, PM-IRRAS was used to evaluate the molecular composition and orientation as well as the intermolecular hydrogen bonding within the SAMs. Finally, XPS was used to evaluate the film composition and surface coverage (i.e., packing density), which was observed to increase in the following order: TP < MP < MPBA < MBA. A rationalization for the observed packing differences is presented. The XPS data indicate further that ultrahigh vacuum conditions induce the partial dehydration of MPBA SAMs with the concomitant formation of surface boronic anhydride species. Overall, the analytical data collectively show that the MPBA moieties in the SAMs exist in the acid form rather than the anhydride form under ambient laboratory conditions. Furthermore, stability studies find that MPBA SAMs are surprisingly labile in basic solution, where the terminal B-C bonds are cleaved by the attack of hydroxide ion and strongly basic amine nucleophiles. The unanticipated lability observed here should be considered by those wishing to use MPBA moieties in carbohydrate-sensing applications.

Isolation, characterization, and reactivity of the reaction products of the dimeric, Ti–O–Ti bridged anhydride form of the 1,2-di-titanium(IV)-substituted α-Keggin polyoxometalate with aqueous 30% H 2O 2

The isolation and characterization of the monomeric bis[peroxotitanium(IV)]-substituted α-Keggin polyoxometalate (POM) K 7[α-l,2-PW 10(TiO 2) 2O 38]·8H 2O ( 1) and the monomeric bis[hydroperoxotitanium(IV)]-substituted α-Keggin POM K 5[α-l,2-PW 10(TiOOH) 2O 38]·5H 2O ( 2) are described. The orange solution was prepared by adding an excess amount of aqueous 30% H 2O 2 to the in situ-generated monomeric Keggin species [α-1,2-PW 10Ti 2O 40] 7− in a neutral aqueous solution derived by the hydrolytic cleavage of the dimeric, Ti–O–Ti bridged anhydride form K 10[α-l,2-PW 10Ti 2O 39] 2·18H 2O. Reprecipitation of the orange solution with MeOH gave a thermally stable yellow species containing the peroxo groups (compound 1) whereas reprecipitation with EtOH yielded a relatively unstable orange species that would contain the hydroperoxo groups (compound 2). The characterization of 1 and 2 was accomplished by a complete elemental analysis, TG/DTA, FTIR, UV–vis, solution ( 31P and 183W) NMR and 31P CPMAS NMR spectroscopy, and (for 1 only) X-ray crystallography. Complex 1 did not show any activity for 2-propanol oxidation in the absence of 30% H 2O 2 whereas complex 2 showed an effective activity for the oxidation reaction.

Polymer Supported Carbodiimide Strategy for the Synthesis of N‐Acylated Derivatives of Deoxy‐ and Ribo‐Purinenucleosides Using Active Esters.

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Polymer supported carbodiimide strategy for the synthesis of N-acylated derivatives of deoxy- and ribo purinenucleosides using active esters

A cost-effective synthetic strategy has been used for the selective protection of the exocyclic amino function of purine nucleosides. Instead of using the common protecting groups in their chloride or anhydride forms, the less expensive and nontoxic acidic form was chosen. The acids were first activated to an active ester form using DCC and further successfully used for N-acylation of purine nucleosides. The contamination of the N-acylated product with DCU was inconvenient and was avoided by use of polymer supported-carbodiimide that has the additional advantage of reusability.

Isolation and Molecular Structure of a Monomeric, Tris[peroxotitanium(IV)]‐Substituted α‐Dawson Polyoxometalate Derived from the Tetrameric Anhydride Form Composed of Four Tris[titanium(IV)]‐Substituted α‐Dawson Substructures and Four Bridging Titanium(IV) Octahedral Groups.

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Side Chain Extension of Polypropylene by Aliphatic Diamine and Isocyanate

AbstractA post‐reaction modification of polypropylene by which to obtain increased melt strength is by reactive extrusion of randomly functionalized PP with polyfunctional monomers. In this study, reactive melt processing of maleated polypropylene (PP‐g‐MA) with poly[methylene (phenylene isocyanate)] (PMPI), hexamethylene diamine (HMDA), and poly(propylene glycol)‐bis‐(2‐propylamine) (Jeffamine D‐400) was carried out. The resulting chain‐extended PP‐g‐MA was confirmed by FTIR analysis. Its thermal and rheological properties were also measured. HMDA and D‐400 react with both the carboxylic acid and anhydride form of MA. Though PMPI only reacts with the carboxylic acid of MA, PP‐g‐MA reacted with PMPI has higher gel content and storage modulus compared to PP‐g‐MA reacted with the amine. This is because of the higher functionality of PMPI and localized reaction between the isocyanate in PMPI and the carboxylic acid in PP‐g‐MA.

Embedding poly(styrene sulfonic acid) into PVDF matrix?a new type of proton electrolyte membrane

Hydrophilic polymer segments, consisting of styrene sulfonic acid (SSA) units, were uniformly embedded into hydrophobic poly(vinylidene fluoride) (PVDF) matrix through the mediation of poly(methyl methacrylate) (PMMA) segments, with which SSA segments form a copolymer. Discrete domains (∼100 nm) assembled by the SSA segments have been identified throughout the matrix of the membrane, which was prepared through blending of the copolymer P(MMA–SSA) and the PVDF. The thermal stability of the SSA was largely boosted in such hydrophobic environment. This unique matrix structure offers proton conductivity of as high as 10 −3 S/cm at a low SSA equivalent (0.6 mmol –SO 3 H/g of membrane), which is accompanied with a low level of water uptake (26%) at ambient temperature. Using this type of polymer membrane as electrolyte, the electrochemical cell possesses obvious capacitive resistance when the membrane is in the anhydride form according to the impedance analysis. However, the capacitive character vanishes when the membrane is hydrated; this response is attributed to the existence of highly dispersed SSA domains in the membrane. This work also analyzes the impedance spectra of the membranes at different hydrated states or with different SSA contents by using an equivalent electrical circuit.

Embedding poly(styrene sulfonic acid) into PVDF matrix—a new type of proton electrolyte membrane

Hydrophilic polymer segments, consisting of styrene sulfonic acid (SSA) units, were uniformly embedded into hydrophobic poly(vinylidene fluoride) (PVDF) matrix through the mediation of poly(methyl methacrylate) (PMMA) segments, with which SSA segments form a copolymer. Discrete domains (∼100 nm) assembled by the SSA segments have been identified throughout the matrix of the membrane, which was prepared through blending of the copolymer P(MMA–SSA) and the PVDF. The thermal stability of the SSA was largely boosted in such hydrophobic environment. This unique matrix structure offers proton conductivity of as high as 10 −3 S/cm at a low SSA equivalent (0.6 mmol –SO 3H/g of membrane), which is accompanied with a low level of water uptake (26%) at ambient temperature. Using this type of polymer membrane as electrolyte, the electrochemical cell possesses obvious capacitive resistance when the membrane is in the anhydride form according to the impedance analysis. However, the capacitive character vanishes when the membrane is hydrated; this response is attributed to the existence of highly dispersed SSA domains in the membrane. This work also analyzes the impedance spectra of the membranes at different hydrated states or with different SSA contents by using an equivalent electrical circuit.

PEGylation of phospholipids improves their intermembrane exchange rate

The polar headgroup of dimyristoylphosphatidylethanolamine (DMPE) was modified by attaching a hydrophilic polymer-amino acid complex and the effects of this modification on the non-protein-mediated transfer features of the lipid determined. The first step in the organic synthesis protocol was the conversion of α,ω-dicarboxy poly(ethylene glycol) into its anhydride form, followed by attachment of the molecule to the amino group of DMPE. In the second step, the remaining free –COOH group on the polymer terminus was activated consecutively with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and sulfo-N-hydroxysuccinimide, and then coupled to tryptophan. The purified conjugate was mixed with dipentadecanoylphosphatidylglycerol (1/9 molar ratio) and sonicated to produce small unilamellar vesicles. These vesicles (donors) were then mixed with dipentadecanoylphosphatidylglycerol magnetoliposomes (acceptors) and the transfer kinetics of the modified lipid followed, using high-gradient magnetophoresis as the fractionation technique. The transfer behavior of non-modified DMPE was also examined. The first-order kinetic plots, corrected for back exchange lipid movement, showed that hydrophilization of DMPE dramatically improved its transfer capacity. These findings are explained by considering the thermodynamical consequences of the exchange process. The possibility of using biomolecule-derivatized phospholipids to trigger physiological effects in biological cells is briefly discussed.

Tetrameric, trititanium(IV)-substituted polyoxotungstates with an alpha-Dawson substructure as soluble metal-oxide analogues: molecular structure of the giant "tetrapod" [(alpha-1,2,3-P2W15Ti3O62)4[mu3-Ti(OH)3]4Cl]45-.

The preparation and structural characterization of the novel polyoxoanion [(alpha-1,2,3-P(2)W(15)Ti(3)O(62))(4)[mu(3)-Ti(OH)(3)](4)Cl](45-) (1 a; abbreviated to [TiO(6)](16); FW approximately 16 000) which consists of four tri-Ti(IV)-1,2,3-substituted alpha-Dawson substructures, four Ti(OH)(3) bridging groups, and one encapsulated Cl(-) ion, are described. A water-soluble, all-inorganic composition compound of the tetrameric Ti-O-Ti-bridged anhydride form, Na(x)H(45-x)[1 a].y H(2)O (1; x=16-19, y=60-70), which was afforded by the reaction of the tri-lacunary Dawson polyoxotungstate Na(12)[B-alpha-P(2)W(15)O(56)].19 H(2)O with an excess of TiCl(4) in aqueous solution, was obtained as analytically pure, homogeneous colorless crystals. Single-crystal X-ray structure analysis revealed that 1 a was an inorganic, giant "tetrapod"-shaped molecule (inscribed to a sphere with a diameter of approximately 32 A) with approximately T(d) symmetry, in which the 16 edge- and/or corner-shared TiO(6) octahedra were contained. This number of TiO(6) octahedra was larger than that found in other titanium(IV)-substituted polyoxotungstates. Complex 1 was characterized by complete elemental analysis, TG/DTA, FTIR, UV/Vis absorption, and solution ((31)P and (183)W) NMR spectroscopy. The longest wavelength band in the UV/Vis absorption spectra of 1 in water was attributed to the O-->Ti(IV) ligand-to-metal charge-transfer (LMCT) transition: the wavelength of the LMCT band increased linearly as the number of TiO(6) octahedra contained in the Keggin and Dawson polyoxoanions increased. The Ti(n) chromophores formed in the Keggin and Dawson polyoxotungstates are water-soluble analogues of solid TiO(2) or SrTiO(3) as light-semiconductors and photocatalysts.

A first example of polyoxotungstate-based giant molecule. Synthesis and molecular structure of a tetrapod-shaped Ti–O–Ti bridged anhydride form of Dawson tri-titanium(iv)-substituted polyoxotungstate

The preparation and structural characterization of a giant “tetrapod”-shaped inorganic molecule, [(α-1,2,3-P2W15Ti3O60.5)4Cl]37− ,1a (abbreviated to {TiO6}12; FW ∼15700), consisting of four tri-TiIV-1,2,3-substituted α-Dawson substructures and one encapsulated Cl− ion, are described. A water-soluble, all-inorganic composition compound of the tetrameric Ti–O–Ti bridged anhydride form, NaxH33−xK4[1a]·yH2O, 1 (x = 21–26, y = 60–70), being afforded by a stoichiometric reaction in aqueous solution of tri-lacunary Dawson polyoxotungstate Na12[B-α-P2W15O56]·19H2O with 3 equiv of Ti(SO4)2·4H2O in HCl-acidic aqueous solution followed by exchanging the countercation, was obtained as analytically pure, homogeneous colorless plate crystals. Single-crystal X-ray structure analysis revealed that the polyoxoanion 1a was an inorganic, giant “tetrapod”-shaped molecule (described as a sphere with a diameter of ∼31.2 A) with approximately Td symmetry. Characterization of 1 was also accomplished by complete elemental analysis, TG/DTA, FTIR, UV-vis absorption and solution (31P and 183W) NMR spectroscopy.

Physiological factors influencing the antifungal activity of zopfiellin

Zopfiellin, a novel cyclooctanoid natural product isolated from Zopfiella curvata No. 37-3, was evaluated for antifungal activity and its mechanism of action was investigated. Fungal growth inhibition caused by zopfiellin was mediated by the pH of the growth medium. Maximum inhibitory activity was obtained between pH 5 and 5.5. Intramolecular ring closure of zopfiellin from a tetracarboxylate to an anhydride form occurring at pH below 6 is apparently required for uptake by the fungus. Biological activity of zopfiellin could be reversed by exogenous addition of oxaloacetate under both glycolytic and gluconeogenic growth conditions. The in vitro activity of zopfiellin was tested on the enzyme phosphoenolpyruvate carboxykinase, a regulatory enzyme in the gluconeogenesis pathway catalyzing the conversion of oxaloacetate to phosphoenolpyruvate. The mechanism of antifungal activity of zopfiellin appears to be associated with physiological processes involving oxaloacetate metabolism.

Synthesis and pH-variable ultracentrifugation molecular weight measurements of the dimeric, Ti–O–Ti bridged anhydride form of a novel di-TiIV-1,2-substituted α-Keggin polyoxotungstate. Molecular structure of the [(α-1,2-PW10Ti2O39)2]10−polyoxoanion

The preparation and characterization of a Keggin-type, novel di-TiIV-1,2-substituted polyoxotungstate are described. The dimeric, Ti–O–Ti bridged anhydride form of the di-TiIV-1,2-substituted α-Keggin polyoxotungstate, K10[α,α-P2W20Ti4O78]·12H2O 1, was unexpectedly found in the varied molar-ratio reactions of tri-lacunary precursor Na9[A-PW9O34]·19H2O with Ti(SO4)2 in aqueous solution. Although this compound was first found as a minor product in the preparation of the dimeric, tri-TiIV-1,2,3-substituted species, K10H2[α,α-P2W18Ti6O77]·17H2O 3, it was successfully prepared as a main product in this work and structurally characterized. Compound 1, as analytically pure, homogeneous colorless needle crystals, was obtained as a major product in 29.2% yield (2.7 g scale) from recrystallization under acidic conditions (at pH 2.2) of the 1 ∶ 2 molar-ratio reaction product. X-Ray structure analysis revealed that the molecular structure of 1 consisted of a dimeric anhydride formed by two Ti–O–Ti bonds linking two [α-1,2-PW10Ti2O40]7− Keggin units. Interestingly, ultracentrifugation molecular weight (MW) measurements of this compound in aqueous solution showed the pH-dependent interconversion between monomer [α-1,2-PW10Ti2O40]7−2 and dimer [α,α-P2W20Ti4O78]10−1; this compound was present as the monomer under less acidic conditions (pH 7.8), while it was in dimeric form under more acidic conditions (pH 1.0 and 2.2). Characterization of 1 was also accomplished by complete elemental analyses, TG/DTA, FTIR and solution (31P and 183W) NMR spectroscopy.