Vinyl Double Bond Research Articles

Ozone as a Pretreatment Method for Antibiotic Contaminated Wastewater and Sludge

ABSTRACTThe capability of ozone to reduce the hazardous impact of environmentally persistent antibiotic tiamulin in term of toxicity reduction and enhancement of biodegradability was investigated. Different ozone doses were applied but ozonation was not effective enough to increase the biodegradability of tiamulin in the aqueous phase. The opposite effect was observed in anaerobic digestion experiments, where ozonation as a pretreatment step of antibiotic-contaminated sludge detoxify tiamulin and improves biogas production for 75%. As confirmed by 1H NMR and HPLC-HRMS analyses, the tiamulin molecule completely reacts with ozone at low ozone/COD molar ratio of 0.03, primarily attacking the vinyl double bond with further oxidation of sulfur and nitrogen atom, and gradual decomposition of tiamulin skeleton.

Regioselectivity and Reactivity of Intramolecular [2+2] Cycloaddition Reactions of Acyl Ketenes: Experimental and Theoretical Studies

The regioselectivity of the intramolecular [2+2] cycloaddition reaction of acyl ketenes formed from metastable mesoionic 1,3-oxazinium-4-olates was investigated by experimental and theoretical methods. The ring opening of the mesoionic N-allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates led to the formation of unstable acyl ketenes. ­Although there are four possible paths for an intramolecular [2+2] cyclo­addition reaction involving the two double bonds (vinyl and allyl), only the intramolecular [2+2] criss-cross cycloaddition reaction through the vinyl double bond occurred to give 3-allyl-3-azabicyclo[3.1.1]heptane-2,4,6-trione derivatives. These products were not formed when a strongly electron-withdrawing group was present on the aryl group of acrylamides or benzamides. To understand the mechanism of the reaction, density functional theory calculations at the M06-2X/6-31+G(d) level were performed. These revealed that the formation of some preliminary intermediates plays a significant role in the formation of mesoionic 1,3-oxazinium-4-olates.

Research into epoxidation process of the С9 fraction hydrocarbons and unsaturated co-oligomers by peroxyethanoic acid

We have studied regularities of the epoxidation process of the С 9 fraction of liquid by-products of the pyrolysis of hydrocarbons and co-oligomers based on the С 9 fraction with peracetic acid. It is established that the use of the specified system makes it possible to achieve high values of conversion for double bonds and the selectivity of epoxidation process, sufficiently high yield of epoxy-containing co-oligomers. We established the possibility to use the С 9 fraction of liquid by-products of hydrocarbon pyrolysis (the accompanying product of ethylene production) as a raw material for obtaining epoxides, which is a rational method in order to dispose of the fraction. We analyzed experimental dependences of reagents consumption and the formation of epoxide in the reaction of the С 9 fraction epoxidation. It was established that the resulting values for selectivities of the epoxidation process by double bonds when obtaining epoxy-containing co-oligomers are the highest in the case of epoxidation of co-oligomers, synthesized by the heterogeneous catalytic co-oligomerization of the С 9 fraction S9 hydrocarbons using, as a catalyst, activated bentonite clay. The synthesized epoxy-containing co-oligomers retain residual unsaturation. It is obvious that the unsaturated bonds of styrene, vinyl toluene, α-methyl styrene, allylbenzene links at the ends of a co-oligomer macromolecules are easily epoxidized. The selectivity of epoxidation of co-oligomers, obtained by different methods of co-oligomerization of the С 9 fraction hydrocarbons (homogeneous catalytic, heterogeneous catalytic, initiated, and thermal) is different (60.2‒96.1 %) and depends on the nature of the starting co-oligomer. Using the methods of 1 H NMR-, Raman-, and infrared spectroscopy, we confirmed the high content of epoxy groups in the composition of epoxy-containing co-oligomers and the progress of the epoxidation reaction. Applying the method of 1 H NMR spectroscopy, we established the presence of epoxy groups formed based on the resulting vinyl double bonds of co-oligomers. Due to the content of oxirane oxygen and a high reaction ability of the oxirane ring, epoxy-containing co-oligomers can act as the raw material for subsequent obtaining of various chemical substances: glycols, carbonyl compounds, plasticizers, polymers.

TUNING PROPERTIES AND MORPHOLOGY IN HIGH VINYL CONTENT SBS BLOCK COPOLYMER, A THERMOPLASTIC ELASTOMER VIA THIOL-ENE MODIFICATION

ABSTRACT Thiol-ene modification of high vinyl content thermoplastic elastomeric styrene butadiene styrene (SBS) block copolymer (BCP) was carried out using different thiolating agents in toluene at 70 °C. 1H NMR analysis confirmed the participation of vinyl double bond in the thiol-ene modification reaction of SBS. Surface morphology of the block copolymers evaluated by atomic force microscopy analysis showed higher roughness after the thiol-ene reaction. The thiol-modified SBS block copolymer showed better adhesion strength and oil resistance properties than the pristine SBS.

An exhibition of different coordination modes displayed by 2-vinylpyrazine and 2-vinylpyridine at triosmium centres

The reactivity of 2-vinylpyrazine and 2-vinylpyridine at different triosmium clusters has been investigated. Room temperature reaction of 2-vinylpyrazine with formally unsaturated [Os3(CO)10(μ-H)2] or lightly-stabilized [Os3(CO)10(NCMe)2] leads to the formation of [HOs3(CO)10(μ-C4H3N2CH=CH)] (1) through β-vinyl C─H bond activation. In contrast, direct reaction between [Os3(CO)12] and 2-vinylpyrazine at elevated temperatures affords [Os3(CO)10(μ-C4H2N2CH=CH2)(μ-H)] (2) via aryl C─H bond activation. The metalated 2-vinylpyrazine ligand acts as a five-electron donor in 1, but serves as a three-electron donor in 2. The high temperature reaction between 2-vinylpyrazine with the bis(diphenylphsophino)methane (dppm) substituted cluster [Os3(CO)8(μ-H)2(μ-dppm)] furnishes [Os3(CO)8(μ-C4H3N2CH=CH){μ-Ph2PCH2P(Ph)C6H4}] (3) and [Os3(CO)6(η2-C4H3N2CH=CH2)(μ3-C4H3N2CH=C)(μ-dppm)] (4) through single and double β-vinyl C─H bond activation, respectively. The metalated 2-vinylpyrazine ligand acts as five- and six-electron donors in 4 and 5, respectively. Cluster 5 also contains an intact 2-vinylpyrazine ligand coordinating to an osmium like an olefin using the vinylic double bond thus serving as a two-electron donor. A similar reaction between [Os3(CO)8(μ-H)2(μ-dppm)] and 2-vinylpyridine affords the analogous [Os3(CO)8(μ-C5H4NCH=CH){μ-Ph2PCH2P(Ph)C6H4}] (5) and [Os3(CO)6(η2-C5H4NCH=CH2)(μ3-C5H4NCH=C)(μ-dppm)] (6). The solid-state molecular structures of 1–6 have been determined by single crystal X-ray diffraction analysis.

Synthesis and cytotoxic activities of goniothalamins and derivatives

Substituted goniothalamins containing cyclopropane-groups were efficiently prepared in high yields and good selectivity. Antiproliferative activity was measured on three human cancer cell lines (A549, MCF-7, HBL-100), to show which of the structural elements of goniothalamins is mandatory for cytotoxicity. We found that the configuration of the stereogenic centre of the δ-lactone plays an important role for cytotoxicity. In our studies only (R)-configured goniothalamins showed antiproliferative activity, whereby (R)-configuration accords to natural goniothalamin (R)-1. Additionally, the δ-lactone needs to be unsaturated whereas our results show that the vinylic double bond is not mandatory for cytotoxicity. Furthermore, with a two-fold in vitro and in vivo strategy, we determined the inhibitory effect of the compounds to the yeast protein Pdr5. Here, we clearly demonstrate that the configuration seems to be of minor influence, only, while the nature of the substituent of the phenyl ring is of prime importance.

QM/MM Study of Substituent and Solvent Effects on the Excited State Dynamics of the Photoactive Yellow Protein Chromophore.

Substituent and solvent effects on the excited state dynamics of the Photoactive Yellow Protein chromophore are studied using the average solvent electrostatic potential from molecular dynamics (ASEP/MD) method. Four molecular models were considered: the ester and thioester derivatives of the p-coumaric acid anion and their methylated derivatives. We found that the solvent produces dramatic modifications on the free energy profile of the S1 state: 1) Two twisted structures that are minima in the gas phase could not be located in aqueous solution. 2) Conical intersections (CIs) associated with the rotation of the single bond adjacent to the phenyl group are found for the four derivatives in water solution but only for thio derivatives in the gas phase. 3) The relative stability of minima and CIs is reverted with respect to the gas phase values, affecting the prevalent de-excitation paths. As a consequence of these changes, three competitive de-excitation channels are open in aqueous solution: the fluorescence emission from a planar minimum on S1, the trans-cis photoisomerization through a CI that involves the rotation of the vinyl double bond, and the nonradiative, nonreactive, de-excitation through the CI associated with the rotation of the single bond adjacent to the phenyl group. In the gas phase, the minima are the structures with the lower energy, while in solution these are the conical intersections. In solution, the de-excitation prevalent path seems to be the photoisomerization for oxo compounds, while thio compounds return to the initial trans ground state without emission.

Preparation of a self-curable unsaturated polyester with vinyl double bonds and Investigation of its self-curing properties

In this paper, a kind of self-curable unsaturated polyester PGA-UP with vinyl groups on the end of molecule chains was synthesized through esterification reaction of glycidol with acrylic acid. The self-curable function of unsaturated polyester was put forward as a new solution to air pollution problems caused by the cross-linking monomer’s volatilization in unsaturated polyesters (UP) industry. The synthetic method, reaction process, molecular structure and self-curing properties were studied. Investigation demonstrates that the unsaturated polyester resin PGA-UP could be synthesized through a two-step process and the liquid product was a mixed outcome of different extent esterification. The unsaturated polyester resin could be self-cured through the free radical reaction of vinyl groups on the end of the molecules when they were initiated by 1% benzoyl peroxide (BPO) at 80°C for 1 hours and 120°C for 2 hours with no cross-linking monomers. The intension strength of the self-cured PGA-UP is 13.5Mpa, close to the 15.6MPa of an usual unsaturated polyester S-UP made in our lab. The self-curable PGA-UP presents good potential application and the research will contribute to improve the environmental problems caused by volatile of cross-linking monomers in unsaturated polyester applications. 1H-NMR and FT-IR were used to characterize.

Thermally Degradable Polyesters with Tunable Degradation Temperatures via Postpolymerization Modification and Intramolecular Cyclization

We report the novel synthesis of thermally degradable polyesters through the postpolymerization modification of an unsaturated aliphatic polyester from maleic acid via Michael addition reaction with β-amino mercaptans. A high molecular weight polyester (P0) was synthesized by the acyclic diene metathesis (ADMET) polymerization of a diene monomer, di(10-undecenyl) maleate. Postpolymerization modification of P0 with three β-amino mercaptans (2-aminoethanethiol, l-cysteine methyl ester, and 2-(butylamino)ethanethiol) and 2-mercaptoethanol via the selective and quantitative thiol–Michael addition reaction with the maleate vinylic double bonds afforded four polyesters (P1–P4). All the polyesters were characterized by 1H NMR, GPC, and MALDI-TOF-MS, and their thermal properties were studied by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The three polymers with pendant amino groups (P1–P3) subjected to thermal-induced degradation in the solid state, the driving force of which i...

A novel dual-responsive core-crosslinked magnetic-gold nanogel for triggered drug release

A facial approach was reported to prepare a novel dual-responsive core-crosslinked nanogel and investigated for the triggered methotrexate (MTX) release. Nanogels with core-shell architecture were synthesized by decoration of Au/Fe3O4 core/shell NPs using poly(ethylene glycol)-b-poly((N,N-dimethylamino)ethyl methacrylate-co-2-hydroxyethyl methacrylate)-maleic acid (PEG-b-P(DMAEMA-co-HEMA)-MA) for crosslinking and autoreduction processes. The second block containing amino groups and maleate groups as the inner shell was used for the reduction of HAuCl4 (auric cation) in the presence of Fe3O4 NPs and as a crosslinker agent, respectively. Furthermore, to improve the long-term dispersibility of the nanogels, poly(ethylene glycol) was preferred as outer shell even under high ionic strength. After that, NIPAAm was polymerized from the vinyl double bonds for fabricating the thermo and pH-responsive core-crosslinked nanogels. MTX (an anti-cancer agent) was successfully loaded (the loading capacity of 37%) into the nanogels by both ionic interaction and entrapment in polymeric network in the inner shell. The triggered MTX release ability of the synthesized nanocarriers was proved through the comparison of in-vitro drug release at simulated physiological condition and tumor tissue environment. MTT assay showed that MTX-loaded nanocarriers revealed high antitumor activity in MCF7 cell line after incubation following 24 and 48h. It was concluded that the developed nanogels have many promising qualities as an efficient carrier for the targeted MTX delivery to cancer tissues.

ChemInform Abstract: Sequential Oxidative α‐Cyanation/anti‐Markovnikov Hydroalkoxylation of Allylamines.

Iron-catalyzed oxidative α-cyanations at tertiary allylamines in the allylic position are followed by anti-Markovnikov additions of alcohols across the vinylic CC double bonds of the initially generated α-amino nitriles. These consecutive reactions generate 2-amino-4-alkoxybutanenitriles from three reactants (allylamines, trimethylsilyl cyanide, and alcohols) in one reaction vessel at ambient temperature.

Synthesis of Lipophilic Antioxidants by a Lipase-B-Catalyzed Addition of Peracids to the Double Bond of 4-Vinyl-2-methoxyphenol.

4-Vinyl guaiacol (2) was lipophilized through the electrophilic addition of peracids to its vinylic double bond. Those peracids were formed in situ, by the Candida antarctica lipase-B-assisted perhydrolysis of carboxylic acids ranging from C2 to C18, in hydrogen peroxide solution. The addition of peracids with 4-8 carbons in their alkyl chains led to the formation of two regioisomers, with the prevalence of hydroxyesters bearing a primary free hydroxyl (4c-4e). This prevalence became more pronounced when peracids with longer alkyl chains (C10-C18) were used. In this case, only isomers 4f-4h were formed. The antioxidant activity of the resulting hydroxyesters was assessed by means of the conjugated autoxidizable triene (CAT) assay, and it was found out that the 4-vinyl guaiacol antioxidant activity was significantly increased by grafting alkyl chains with 2-8 carbons.

Introduction of Methyl Groups at C2 and C6 Positions Enhances the Antiangiogenesis Activity of Curcumin.

Curcumin has diverse biological activities, but is known to undergo rapid metabolism via reduction of vinylic double bonds and phase II conjugation. To prevent reductive metabolism of curcumin, we introduced a methyl group at both C2 and C6 positions (compound 1) or at the C2 position (compound 2) of curcumin, creating steric hindrance on double bonds against metabolizing enzymes. As predicted, these compounds were resistant to reduction by alcohol dehydrogenase. Compound 1 was further evaluated for its antiangiogenesis activity in vitro and in vivo. It exhibited significantly greater inhibitory activity than curcumin against endothelial cell migration, invasion, and tube formation. Similarly, the in vivo Matrigel plug assay in C57BL/6 mice showed more pronounced reduction of blood vessels in the plugs containing 1 than those containing curcumin. Moreover, 1 suppressed tumor growth more effectively than curcumin in a U87MG mouse xenograft model by inhibiting angiogenesis. In vivo metabolite analysis by liquid chromatography/mass spectrometry demonstrated that 1 underwent markedly slower reductive metabolism than curcumin. Taken together, our results indicate that 1 has enhanced antiangiogenesis activity and suppression of tumor growth compared with curcumin, reflecting diminished reductive metabolism owing to the introduction of methyl groups at the C2 and C6 positions of curcumin.

Sequential Oxidative α-Cyanation/Anti-Markovnikov Hydroalkoxylation of Allylamines.

Iron-catalyzed oxidative α-cyanations at tertiary allylamines in the allylic position are followed by anti-Markovnikov additions of alcohols across the vinylic CC double bonds of the initially generated α-amino nitriles. These consecutive reactions generate 2-amino-4-alkoxybutanenitriles from three reactants (allylamines, trimethylsilyl cyanide, and alcohols) in one reaction vessel at ambient temperature.

Synthesis and Free Radical Copolymerization of a Vinyl Monomer from Soybean Oil

A one-step method that converts soybean oil into (acryloylamino)ethyl soyate, a new vinyl monomer of free radical polymerization, was developed. The synthesized monomer combines a vinyl double bond (acryloyl functional group) and nonconjugated (isolated) double bonds of fatty acids. The double bond of the acryloyl group is reactive in a free radical chain polymerization that yields linear macromolecules containing isolated double bonds in side chains. Monomer reactivity ratios (r1, r2) in copolymerization of the new soybean oil-based acrylic monomer (SBA) with styrene, methyl methacrylate, and vinyl acetate, as well as the Q–e parameters of the SBA, were determined. The obtained results indicate that copolymerization can be described with the classical Mayo–Lewis equation. In terms of polymerizability, the SBA can be classified as an acrylic monomer. The double bonds of the fatty acid chains remain mainly unaffected during the free radical polymerization. The remaining unsaturated fragments in the side ch...

Quinine Derivative Bonded the Hybrid Mesoporous Silicas Chiral Stationary Phase: Preparation and Application in Liquid Chromatography

AbstractA novel chiral stationary phase (QN‐APEPMOs) was synthesized by immobilizing quinine derivative (QN) onto spherical ammoniapropyl‐functionalized ethane‐bridged periodic mesoporous organosilicas (APEPMOs). The mesoporous material was prepared by a one‐step co‐condensation of 1,2‐bis (triethoxysilyl) ethane (BTSE) and 3‐ammoniapropyl triethoxysilane (KH‐550) using cetyltrimethyl‐ammoniumchlorine (C18TACl) as a template with the aid of ethanol (co‐solvent) in basic medium. And O‐9‐(tert‐butyl carbamoyl) quinine derivative was immobilized on APEPMOs particles through the vinylic double bond. All of the products were characterized. The results showed that APEPMOs were perfect substrates for chiral stationary phase (CSP) and quinine moieties have been successfully immobilized onto the silica gel. To evaluate the chiral discrimination ability of the synthesized CSP, some analytes have been investigated on QN‐APEPMOs in high performance liquid chromatography (RP‐HPLC) in reversed phase. Three acidic compounds were baseline separated. The results demonstrated that QN‐APEPMOs had high selectivity for acidic compounds such as: carboxylic and sulfonic acids. And the reproducibility of the chiral column was good, while the stability was not very good.

Preparation of N-Isopropylacrylamide/Itaconic Acid Magnetic Nanohydrogels by Modified Starch as a Crosslinker for Anticancer Drug Carriers

A novel approach is presented for the synthesis of thermoresponsive and pH-sensitive magnetic nanohydrogels by using the biodegradable starch-maleate as a crosslinker and magnetic nanoparticles stabilizer. Chemically modified starch-maleate produces highly stable Fe3O4 magnetic nanopaticles (MNPs) aqueous dispersion. Then, N-isopropylacrylamide (NIPAAm) and itaconic acid (IA) are successfully polymerized from the vinyl double bonds of the starch-maleate-MNPs to prepare the thermo- and pH-responsive magnetic nanohydrogels. The obtained PNIPAAm-g-(starch-MNPs) and (PNIPAAm-co-IA)-g-(starch-MNPs) nanohydrogels are characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometer, X-ray diffraction, differential scanning calorimetry, thermal gravimetric analysis, and vibrating sample magnetometer. Also, pH- and temperature-responsive behaviors of the synthesized magnetic nanohydrogels are investigated and, finally, the cytotoxicity and drug loading are examined with mitoxantrone (MTX) as an anticancer drug model. The results confirm the low toxicity and enhanced anticancer effect of MTX-loaded magnetic nanohydrogels.

Characterization of asphaltenic material obtained by treating of vacuum residue with different reactive molecules

Natural bitumen which is generally used for highway paving has a short life cycle, due to traffic load and drastic change of pressure and temperature. To get the appropriate physical properties of this bitumen, it is generally modified by using reactive molecules. In this study, glycerol, styrene, methyl methacrylate (MMA), hydroquinone (HQ), and C18 acrylate molecules are used as modifiers. The required amounts of the modifier and bitumen are heated at 200°C for 8h with continuous stirring. The asphaltene is extracted from these modified bitumen by soxhlet process. The physical properties of the dried asphaltene are characterized by XRD, SEM and TGA. Results show that the hardness properties, like penetration, softening point, ductility of the natural bitumen are substantially improved after treatment with the modifiers. XRD results indicate that asphaltenes extracted from the modified bitumens become more compact than the asphaltene from the natural bitumen. The results also show that the number of aromatic sheets increases due to the treatment of natural bitumen with the modifiers. The asphaltene derived from C18-acrylate modified bitumen has the maximum number of aromatic sheets. The presence of vinyl double bond and –COOR functional group in C18-acrylate helps effectively the polymerization reaction between the modifier and the natural bitumen. SEM and TGA results also support the presence of a high degree of polymerization/structural arrangement in the asphaltene obtained from this modified bitumen.

Unsaturated Polyesters with Pendant Double Bonds and Investigation of their Self Curable Activity

In this paper, the self-curable unsaturated polyester was put forward as a new solution to air pollution problems caused by the cross-linking monomer’s volatilization in unsaturated polyesters (UP) industry. Two kinds of unsaturated polyesters with the vinyl double bonds at the side chain were synthesized with Itaconic acid (IA) or Itaconic anhydride (ITA) as raw materials. The first one was prepared with IA, isophthalic acid and propylene glycol (IPP-UP), and the second one was synthesized with glycidol (GL) and ITA (IG-UP). Investigation demonstrates that the latter UP resin could be self-cured through the nucleophilic addition reaction of hydroxyl groups with double bonds or the free-radical homopolymerization of double bonds when they were heated without cross-linking monomers. However, the former couldn’t. Factors on self-crosslinking activity and crosslinking mechamism of pendant vinyl bonds from IA or ITA were explored.1H-NMR and FT-IR were used to characterize.

Synthesis and photophysical properties of fluorescent arylstyrylimidazo[1,2-a]pyridine-based donor-acceptor chromophores

A series of novel fluorescent arylstyrylimidazo[1,2-a]pyridines was synthesized and fully characterized. All styryl derivatives have an E-configuration of the vinyl double bond as unequivocally shown by 1H NMR spectroscopy. It was observed that the E isomers are stable in the solid state; however, the derivatives with strong electron donating dialkylamino substituents underwent partial E-Z isomerization in solution at room temperature. The styryl derivatives absorb in the UV or visible region and emit light with moderate Stokes shifts. These compounds exhibit fluorosolvatochromism, namely the emission band is red shifted with increasing solvent polarity. Moreover, the absorption and emission properties of the styryl derivatives change drastically upon acidification, as the protonation of the nitrogen atoms of the imidazo[1,2-a]pyridine ring increases the donor-acceptor interplay of the π system.