Epoxy Moiety Research Articles

Synthesis and chemical reactivity of tetrahydro[60]fullerene epoxides with both amino and aryl addends.

Tetrahydro[60]fullerene epoxides C60(O)Ar(n)(NR2)(4-n), n = 1, 2, have been prepared by treating 1,4-adducts C60(OH)Ph and C60(Tol)2 with cyclic secondary amines. The epoxy moieties in these mixed tetrahydro[60]fullerene epoxides were hydrolyzed into the corresponding diol derivatives, which were further oxidized into diketone open-cage fullerenes with a 10-membered orifice. A few other reactions also showed that the present tetrahydro[60]fullerene epoxides with both amino and aryl addends exhibit improved chemical reactivity over the tetraamino[60]fullerene epoxide without any aryl group.

Graphene oxide powders with different oxidation degree, prepared by synthesis variations of the Hummers method

Graphene oxide (GO) powders with different oxidation degree estimated through the relative intensity of the infrared absorption bands related to oxygen containing groups were prepared through variations of the Hummers method. The GO powders were analyzed by Transmission Electron Microscopy, Energy dispersive spectroscopy, X-ray Photoelectron Spectroscopy, Fourier Transform Infrared Spectroscopy, Raman spectroscopy, X-ray Diffraction, UV–VIS spectroscopy and Electrical Resistance measurements. Several square micron GO sheets with low wrinkling were obtained. Oxygen to carbon ratio is around 0.2 in all the samples although a strong variance in the relative intensity of the oxygen related infrared bands is evident. Thus, the oxidation degree was estimated from the FTIR measurements using the quotient between the C–O related bands area to the total area under the spectra. FTIR shows presence of hydroxyl (–OH), epoxy (C–O–C), carboxyl (–COOH) and carbonyl (CO) moieties and evidence of intermolecular interactions between adjacent groups. These interactions influence the exfoliation degree, the absorbance of the GO suspensions, as well as the electrical resistance, while the crystalline domain sizes, estimated from XRD and Raman do not show a noticeable behavior related with the composition and molecular structure. The results indicate that the electrical resistance is influenced mainly by the surface chemistry of the GO powders and not only by the O/C ratio. The control of the surface chemistry of GO powders would allow their use as additives in organic bulk heterojunction solar cells with enhanced photoconversion efficiency.

Modeling of Toluene Sulfonic Acid Catalyzed Oxide Addition Reaction for Soy-Based Polyol

Polyol oligomers formed from reactions of mono-, di-, and triethylene glycols with epoxidized soybean oil were synthesized and the reaction conversions were modeled. The data verified the effectiveness of a model that is based on the simultaneous solution of eight ordinary differential equations. In addition, the data demonstrated that di- and triethylene glycols produced lower viscosity oligomers than monoethylene glycol. Since the model is fundamentally based, it provides insight into the reaction mechanisms and allows for simulation of reaction conditions with reasonable extrapolation. Within the accuracy of the data, the reaction rate coefficients for all alcohol and epoxy moieties were equal, independent of the molecule to which they were attached—reaction rates varied based only on temperature and dilution of reacting moieties. The model provides an effective means to simulating concentration, viscosity, and temperature profiles including estimates of degrees of polymerization, which are dependent on a parameter related to inter versus intra-oligomerization.

Chromatographic assessment of two hybrid monoliths prepared via epoxy-amine ring-opening polymerization and methacrylate-based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer

Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65°C for 12h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60°C for 12h. Two hybrid monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA–DAD monolith possessed higher column efficiencies (25,000–34,000plates/m) for the separation of alkylbenzenes than the epoxy-MA–EDMA monolith (12,000–13,000plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine monoliths, the epoxy-MA–EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA–DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA–DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA–DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA–EDMA monolith when compared with that on pristine epoxy-MA–EDMA monolith. The enhancement of the column efficiency of epoxy-MA–DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC.

Polymerization of an epoxy‐containing silacyclobutane and its application to networked polymer synthesis

ABSTRACTPolymerization of a silacyclobutane having an epoxy moiety and its application to networked polymer synthesis were examined. Four‐membered ring‐opening polymerization of silacyclobutane having a 3,4‐epoxybutyl group on the silicon atom (OBMSB) was achieved by using a platinum vinyldisiloxane complex with keeping the epoxy ring unchanged. Copolymerization of 1,1‐diethylsilacyclobutane (DESB) with OBMSB by using the same catalyst effectively gave the corresponding copolymers [poly(DESB‐co‐OBMSB)]. Thermal properties of the polyOBMSB, polyDESB, and poly(DESB‐co‐OBMSB) were investigated by DSC and TGA. Cast films of the obtained polymers with 1‐naphthylmethylmethyl‐p‐hydroxyphenylsulfonium hexafluoroantimonate, a small amount of thermally latent acid generator were prepared. Heating the films at 80 °C for 2 h gave crosslinked networked polycarbosilanes through cationic ring‐opening of the epoxy moieties. Thermal and mechanical properties of the networked polymers were investigated by TGA, DSC, and tensile strength measurements. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3400–3405

Identification and characterization of a new erythromycin biosynthetic gene cluster in Actinopolyspora erythraea YIM90600, a novel erythronolide-producing halophilic actinomycete isolated from salt field.

Erythromycins (Ers) are clinically potent macrolide antibiotics in treating pathogenic bacterial infections. Microorganisms capable of producing Ers, represented by Saccharopolyspora erythraea, are mainly soil-dwelling actinomycetes. So far, Actinopolyspora erythraea YIM90600, a halophilic actinomycete isolated from Baicheng salt field, is the only known Er-producing extremophile. In this study, we have reported the draft genome sequence of Ac. erythraea YIM90600, genome mining of which has revealed a new Er biosynthetic gene cluster encoding several novel Er metabolites. This Er gene cluster shares high identity and similarity with the one of Sa. erythraea NRRL2338, except for two absent genes, eryBI and eryG. By correlating genotype and chemotype, the biosynthetic pathways of 3′-demethyl-erythromycin C, erythronolide H (EH) and erythronolide I have been proposed. The formation of EH is supposed to be sequentially biosynthesized via C-6/C-18 epoxidation and C-14 hydroxylation from 6-deoxyerythronolide B. Although an in vitro enzymatic activity assay has provided limited evidence for the involvement of the cytochrome P450 oxidase EryFAc (derived from Ac. erythraea YIM90600) in the catalysis of a two-step oxidation, resulting in an epoxy moiety, the attempt to construct an EH-producing Sa. erythraea mutant via gene complementation was not successful. Characterization of EryKAc (derived from Ac. erythraea YIM90600) in vitro has confirmed its unique role as a C-12 hydroxylase, rather than a C-14 hydroxylase of the erythronolide. Genomic characterization of the halophile Ac. erythraea YIM90600 will assist us to explore the great potential of extremophiles, and promote the understanding of EH formation, which will shed new insights into the biosynthesis of Er metabolites.

Vinylphenylglycidyl ether-based colloidal architectures: high-functionality crosslinking reagents, hybrid raspberry-type particles and smart hydrophobic surfaces

An efficient synthetic strategy for the preparation of monodisperse colloidal core/shell architectures with reactive epoxy functionalities is reported, based on the bifunctional vinylphenylglycidyl ether monomer. Accessibility of the reactive immobilized epoxy moieties was quantified by UV/vis spectroscopy in an isorefractive medium. Inorganic–organic hybrid raspberry-type architectures revealed a tremendous inpact on the surface wettability of water.

Facile Fabrication of Polymeric Ionic Liquid Grafted Porous Polymer Monolith for Mixed‐Mode High Performance Liquid Chromatography

AbstractA novel polymeric ionic liquid grafted porous polymer monolith has been facilely fabricated for mixed‐mode chromatography. The column is prepared from poly (glycidyl methacrylate‐co‐ethylene dimethacrylate) monolith through hydrolyzation of the epoxy moieties into hydroxyl groups, followed by "grafting from" polymerization of ionic liquid of 1‐vinyl‐3‐butylimidazolium chloride. Successful modification is characterized by scanning electron microscope, infrared spectroscopy, elemental analysis and mercury intrusion porosimetry. The HPLC performance of developed column is evaluated by separating acidic vitamin B analytes, neutral steroids and basic aromatic amines in mixed‐mode chromatography on a single column, respectively. The ionic liquid affords the monolith with both enhanced separation ability and improved column efficiency.

Effects of various squalene epoxides on coenzyme Q and cholesterol synthesis

2,3-Oxidosqualene is an intermediate in cholesterol biosynthesis and 2,3:22,23-dioxidosqualene act as the substrate for an alternative pathway that produces 24(S),25-epoxycholesterol which effects cholesterol homeostasis. In light of our previous findings concerning the biological effects of certain epoxidated all-trans-polyisoprenes, the effects of squalene carrying epoxy moieties on the second and third isoprene residues were investigated here. In cultures of HepG2 cells both monoepoxides of squalene and one of their hydrolytic products inhibited cholesterol synthesis and stimulated the synthesis of coenzyme Q (CoQ). Upon prolonged treatment the cholesterol content of these cells and its labeling with [3H]mevalonate were reduced, while the amount and labeling of CoQ increased. Injection of the squalene monoepoxides into mice once daily for 6days elevated the level of CoQ in their blood, but did not change the cholesterol level. The same effects were observed upon treatment of apoE-deficient mice and diabetic GK-rats. This treatment increased the hepatic level of CoQ10 in mice, but the amount of CoQ9, which is the major form, was unaffected. The presence of the active compounds in the blood was supported by the finding that cholesterol synthesis in the white blood cells was inhibited. Since the ratio of CoQ9/CoQ10 varies depending on the experimental conditions, the cells were titrated with substrate and inhibitors, leading to the conclusion that the intracellular isopentenyl-PP pool is a regulator of this ratio. Our present findings indicate that oxidosqualenes may be useful for stimulating both the synthesis and level of CoQ both in vitro and in vivo.

Cytotoxic diterpenes from roots of Crossopetalum gaumeri, a Celastraceae species from Yucatan Peninsula

Four new diterpenes, crossogumerins A–D (1–4) along with six known ones (5–10) were isolated from the root bark of Crossopetalum gaumeri, an endemic medicinal plant from the Yucatan Peninsula. Their structures were elucidated on the basis of 1D and 2D NMR techniques, including HMQC, HMBC, and ROESY experiments. Compounds 1–5, 8–10 were evaluated for cytotoxicity against HeLa (carcinoma of the cervix) and Hep-2 (lung carcinoma) human tumor cells lines and against normal Vero cells (African green monkey kidney) in lag and log phase of growth. Podocarpane diterpenes, crossogumerin B (2) and nimbiol (10), exhibited the highest activity against HeLa cells (IC50 values of 3.1 and 8.1μM, respectively), but also selectivity on Vero cells (SI 22.6 and 7.5, respectively). The preliminary SAR studies suggest that an epoxy moiety in ring B and a hydrogen bond-donor group strategically positioned in the diterpene core are important requirements for cytotoxicity and selectivity.

Insights into the Bioactivity of Mensacarcin and Epoxide Formation by MsnO8

Mensacarcin, a potential antitumour drug, is produced by Streptomyces bottropensis. The structure consists of a three-membered ring system with many oxygen atoms. Of vital importance in this context is an epoxy moiety in the side chain of mensacarcin. Our studies with different mensacarcin derivatives have demonstrated that this epoxy group is primarily responsible for the cytotoxic effect of mensacarcin. In order to obtain further information about this epoxy moiety, inactivation experiments in the gene cluster were carried out to identify the epoxy-forming enzyme. Therefore the cosmid cos2, which covers almost the complete type II polyketide synthase (PKS) gene cluster, was heterologously expressed in Streptomyces albus. This led to production of didesmethylmensacarcin, due to the fact that methyltransferase genes are missing in the cosmid. Further gene inactivation experiments on this cosmid showed that MsnO8, a luciferase-like monooxygenase, introduces the epoxy group at the end of the biosynthesis of mensacarcin. In addition, the protein MsnO8 was purified, and its crystal structure was determined to a resolution of 1.80 Å.

Cure kinetics of several epoxy–amine systems at ambient and high temperatures

Epoxy-crosslinker curing reactions and the extent of the reactions are critical parameters that influence the performance of each epoxy system. The curing of an epoxy prepolymer with an amine functional group may be accompanied by side reactions such as etherification. Commercial epoxy prepolymers were cured with different commercial amines at ambient as well as at elevated temperatures. Singularly, only epoxy–amine reactions were observed with diglycidyl ether of bisphenol-A (DGEBA)-based epoxides in our research even upon post-curing at 200°C. Etherification side reaction was found to occur at a cure temperature of 200°C in epoxides possessing a tertiary amine moiety. A combined goal of our research was to understand the effect of tougheners on the cure of epoxy–amine blend. To discern the effect of tougheners on the cure, core–shell rubber (CSR) particles were incorporated into the epoxy–amine blend. It was observed that CSR particles did not restrict the system from proceeding to complete reaction of epoxy moieties. Besides, CSR particles were found to accelerate the epoxy-amine reaction at a lower level of epoxy conversion. The lower activation energy of epoxy–amine reaction of CSR incorporated system compared to control supported the catalytic effect of CSR particles on the epoxy-amine reaction of epoxy prepolymer and amine blends.

Design of an electrochemical biosensing system for xanthine detection and a study on binding interaction of ketoconazole with xanthine oxidase

Xanthine oxidase (XO) was successfully immobilized by covalent attachment on poly(glycidyl methacrylate-co-vinylferrocene) (P(GMA-co-VFc)), a redox copolymer containing pendant epoxy and ferrocene moieties, for the evaluation of both the biosensing properties and the effect of the interaction of ketoconazole (Ktc) with the immobilized XO. The binding interaction between Ktc, a drug used to treat fungal infections, and the immobilized XO on P(GMA-co-VFc) was also studied by fluorescence spectroscopy technique. The binding capacity of the drug was determined using a calibration curve equation that was drawn at excitation wavelength of 300nm using fluorescence spectroscopy. The interaction ability was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and native-PAGE analysis. The enzyme electrode exhibited a linear range from 2.7×10−3 to 0.55mM with a sensitivity of 19.42μAmM−1cm−2 and a detection limit of 8×10−4mM for the detection of xanthine. The activation energy (Ea) and the apparent Michaelis–Menten constant (Kmapp) values were found to be 12.30kJmol−1 and 0.38mM, respectively.

Functional Zein–Siloxane Bio-Hybrids

Bio-hybrid films have been prepared by a sol–gel method starting from thermoplasticized zein (TPZ) and 3-glycidoxypropyltrimethoxysilane (GOTMS). A two-step procedure was adopted including the silane functionalization of zein macromolecules by reactive melting and the subsequent hydrolysis and condensation step of anchored GOTMS units with in situ formation of silsesquioxane (SSQO) nanostructures. These nanostructures bond the zein macromolecules with each other through the reaction of the GOTMS epoxy moieties with zein amine groups. Small angle X-ray scattering, transmission electron microscopy, and FTIR spectroscopy confirmed the formation of the hybrid network consisting of 2 nm-sized SSQO nanostructures dispersed in the zein matrix along with the modification of the hierarchical structure of zein. The organic–inorganic network induces an enhancement of mechanical and functional performances. In fact, owing to the presence of 3 wt % of siloxane as SiO3/2, the maximum stress increases from 1.87 to 11.16 MPa, whereas the water uptake reduces from 100 to 20 wt % with respect to the neat TPZ. Furthermore, the bio-hybrids show an enhanced durability toward the biodegradation process.

Sol–gel incorporation of silica nanofillers for tuning the anti-corrosion protection of acrylate-based coatings

The aim of the present work is to synthesize through sol–gel approach new hybrid polymeric nanocomposites to be used as coating materials. An acrylic-based polymer was prepared by free-radical copolymerization of two monomers widely used for coatings, namely 2-ethylhexylacrylate (EHA) and glycidyl methacrylate (GMA) bearing epoxy moieties, in which silica nanoparticles were incorporated by in situ acid hydrolysis and subsequent condensation of tetraethoxysilane (TEOS). Glycidoxypropyl trimethoxysilane (GPTS) was used as coupling agent to fine-tune the compatibility between organic and inorganic phases. The morphology, mechanical properties and corrosion resistance of thin films applied on aluminum alloys were optimized by varying the content of silica nanoparticles whose properties were strongly affected by the TEOS/GPTS ratios. Performances of the obtained hybrid materials were scrutinized by atomic force microscopy (AFM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and electrochemical impedance spectroscopy (EIS). Thus it was evidenced that an optimum amount of silica nanoparticles with a precise morphology and composition in term of TEOS/GPTS ratio is needed to maintain good coating barrier properties. Outstanding anti-corrosion protection was reached by using optimized hybrid films.

Modification of solid particles with epoxysilanes and characterization by the Preussmann-test

The interaction of 4-(4-nitrobenzyl)pyridine (NBP) with electrophile reagents results in an intensive colored product. This process occurs rapidly and serves as an indication reaction for several electrophilic reagents which is known as Preussmann-test (PT). In this study the application of the PT is firstly presented for surface bonded epoxy groups. 3-Glycidoxypropyltrimethoxysilane (Glymo) has been used for surface functionalization of various solids such as alumo silicate, MgO, Ba-glass, Sr-glass, and various silicas such as Aerosil® 300, OX 50, Sunspheres and silica gel KG 60. The covalent bonding of the epoxy moieties on the particle's surface by the silane function has been demonstrated by solid state NMR spectroscopy. The detection of active epoxy groups was implemented by the use of 13C–{1H}-CP-MAS-NMR and XPS investigations. These both analytical methods require a large demand of time. Advantageously, the PT, which is applied to Glymo functionalized surfaces, enables a fast and certain assignment of the presence of active epoxy groups. The indicator reaction for detection of epoxy groups is the blue coloration of the samples. The reversible switching of the epoxy particles coloration is attributed to residual acid surface groups from the alumo silicates due to the protonation of the alkylated NBP product.

Tailored SWCNT functionalization optimized for compatibility with epoxy matrices

We have modified single walled carbon nanotubes (SWCNTs) with well defined matrix-based architectures to improve interface interaction in SWCNT/epoxy composites. The hardener and two pre-synthesized oligomers containing epoxy and hardener moieties were covalently attached to the SWCNT walls by in situ diazonium or carboxylic coupling reactions. In this way, SWCNTs bearing amine or epoxide-terminated fragments of different molecular weights, which resemble the chemical structure of the cured resin, were synthesized. A combination of characterization techniques such as Raman and infrared absorption (FTIR) spectroscopy, elemental analysis and coupled thermogravimetry-FTIR spectroscopy were used to identify both the functional groups and degree of functionalization of SWCNTs synthesized by the laser ablation and arc-discharge methods. Depending on the type of reaction employed for the chemical functionalization and the molecular weight of the attached fragment, it was possible to control the degree of functionalization and the electronic properties of the functionalized SWCNTs. Improved dispersion of SWCNTs in the epoxy matrix was achieved by direct integration without using solvents, as observed from optical microscopy and rheology measurements of the SWCNT/epoxy mixtures. Composite materials using these fillers are expected to exhibit improved properties while preserving the thermosetting architecture.

Effect of cellulosic nanowhiskers on the performances of epoxidized acrylic copolymers

The aim of the present work is to synthesize new nanocomposites based on an acrylic polymeric matrix loaded with cellulose nanowhiskers (CNWs). The acrylic copolymer was prepared by free-radical copolymerization of two monomers widely used for coating applications, namely 2-ethylhexylacrylate (EHA) and glycidyl methacrylate (GMA) bearing epoxy moieties, while CNWs were extracted from ramie fibers by the means of acid hydrolysis. A series of nanocomposites with various CNW loadings were obtained by solvent casting and were further crosslinked by an UV-induced curing. The extent of the crosslinking was substantiated by Fourier transform infrared spectroscopy (FTIR) whereas morphological, thermo-mechanical as well as optical properties were evaluated before and after the crosslinking by Scanning Electronic Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Dynamical Mechanical Analysis (DMA) and Polarized Optical Microscopy (POM). Thus it was demonstrated that strong interactions occur between the polymeric matrix and CNW, contributing to a significant improvement of the thermal stability and mechanical properties of the nanocomposites. More importantly, nanocomposites exhibit at certain CNW loading interesting optical properties.

Photo-cross-linking and de-cross-linking of modified polystyrenes having degradable linkages

Modified polystyrenes having both epoxy moieties and tertiary ester linkages, tertiary ether linkages, or carbonate linkages were synthesized. The polymer films containing a photoacid generator were photo-cross-linkable. The cross-linked polymer films became soluble in tetrahydrofuran after thermolysis. Photo-cross-linking and thermal decomposition behaviors of the polymers were investigated and discussed in terms of the chemical structures of degradable units. The thermal stability of the polymers was found to be in the order: tertiary ester > tertiary ether > tertiary carbonate.

Synthesis of reactive poly(norbornene): Ring‐opening metathesis polymerization of norbornene monomer bearing cyclic dithiocarbonate moiety

AbstractA norbornene monomer bearing cyclic dithiocarbonate moiety (NB‐DTC) was successfully synthesized from the corresponding precursor having epoxy moiety by its reaction with carbon disulfide. NB‐DTC underwent the ring‐opening metathesis polymerization (ROMP) catalyzed by a ruthenium carbene complex to give the corresponding poly(norbornene). The dithiocarbonate moiety incorporated into the side chain of the obtained poly(norbornene) reacted with amine to afford the corresponding thiourethane moiety with thiol group, which underwent oxidative S‐S coupling and/or addition reaction to the C‐C double bond in the main chain, leading to formation of a cross‐linked polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.