Boron Trifluoride Etherate Research Articles

Microwave-assisted synthesis of poly(glycidyl azide-co-tetrahydrofuran)

The poly(glycidylazide-co-terahydrofuran) [poly(GA-THF)] or GA-THF copolymers are recognized and established as high-energy binders in explosive systems. In present study, we have developed a greener approach for the syntheses of poly(glycidylazide-co-tetrahydrofuran) copolymers using microwave (MW) irradiation technique. Polymerization of epichlorohydrin and tetrahydrofuran was carried out in the presence of borontrifluoride etherate and ethylene glycol to afford polyepichlorohydrin-tetrahydrofuran (PECH-THF) copolymer followed by its reaction with sodium azide in DMF under microwave irradiation to give poly(GA-THF). The poly(GA-THF) copolymer and their precursors were characterized by various spectral techniques such as MS, 1H-NMR, 13C-NMR, UV–visible, and FTIR. The thermal analysis was done by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Molecular weights of these copolymers were determined using GPC techniques. Morphology of these copolymers was visualized using SEM. Our experimental study shows that the microwave irradiation was effective for the second step (azidation reaction) than conventional heating for the synthesis of GA-THF copolymers. Also, the benign syntheses were tackled and explored with range of solvents. Thus, the current methodology, might advent the researchers dealing with these high-energy binder materials in future.

Expedient synthesis of pyrrolo[1,2-a]quinoxalines through one-pot three-component reactions of o-phenylenediamines, 2-alkoxy-2,3-dihydrofurans and ketones

Pyrrolo[1,2-a]quinoxalines were synthesized through a three-component reaction of 2-alkoxy-2,3-dihydrofuran, o-phenylenediamine and ketone. This reaction was performed in nitromethane by using boron trifluoride etherate as catalyst. Mechanism of this reaction involves the following two steps: (i) a condensation reaction of the dihydrofuran with o-phenylenediamine, which produced a N-(2-aminophenyl)pyrrole derivative that can act as a 1,5-bisnucleophile, and (ii) an intramolecular Mannich-type reaction of the bisnucleophile and ketone to produce the pyrrolo[1,2-a]quinoxaline derivative.

Synthesis and Catalytic Reactivity of Bis(amino)cyclopropenylidene Carbene–Borane Adducts

The first reported neutral boron(III) adducts of bis(amino)cyclopropenylidene carbenes (BAC carbenes) have been synthesized, structurally characterized, and applied in homogeneous reaction chemistry. These air-stable adducts have been prepared by the combination of a BAC carbene lithium tetrafluoroborate adduct with borane dimethyl sulfide, boron trifluoride etherate, or dicyclohexylborane. A borenium cation derived in situ from the dicyclohexylborane adduct catalytically reduces unhindered benzyl ketimines, a class of substrate that cannot be reduced by prior borenium catalysts, at room temperature, employing 20 atm of hydrogen gas as the terminal reductant.

Design, Synthesis, Characterization and Electrochemical Properties of BODIPY Dyes Containing Mono, Bis-2-Naphthyloxyhexyloxy and 4-(Benzyloxy)Phenoxyhexyloxy Groups.

In this study, the synthesis of boron dipyrromethene dyes containing mono, bis-2-naphthyloxyhexyloxy and 4-(benzyloxy)phenoxyhexyloxy groups has been reported. Boron dipyrromethene dyes were synthesized from the mono, bis-benzaldehyde derivatives with 2,4-dimethylpyrrole in dichloromethane in the presence of trifluoroacetic, 2,3-dichloro-5,6-dicyano-p-benzoquinon, triethyl amine and boron trifluoride diethyl etherate, respectively. Electrochemical characterization of boron dipyrromethene dyes were carried out with voltammetric measurements. Electrochemical studies show that boron dipyrromethene dyes containing mono, bis-2-naphthyloxyhexyloxy and 4-(benzyloxy)phenoxyhexyloxy groups have reversible one reduction potentials unlike irreversible one oxidation potentials. Graphical Abstract ᅟ.

Wagner–Meerwein rearrangement in 2,6a-epoxyoxireno[e]isoindole series

A cation-catalyzed Wagner–Meerwein skeletal rearrangement in octahydro-2,6a-epoxyoxireno[e]isoindole series was studied. It was shown that the reaction proceeds ambiguously when effected by boron trifluoride etherate in acetic anhydride: the target 4,5-bis(acetoxy)-4,6-epoxycyclopenta[c]pyridines as well as the products of their further degradation, cyclopenta[c]pyridines, were isolated from the reaction mixture in 10–15% yields as single diastereomers.

ChemInform Abstract: Expeditious and Convenient Synthesis of Polycyclic Difluoroboron Complexes of 2‐Oxoindoline‐3‐carboxamides by Tandem Reaction.

AbstractThe boron trifluoride etherate serves as both a catalyst and reactant in the tandem reaction.

Enhancing effect of boron trifluoride diethyl etherate electrolytes on capacitance performance of electropolymerized poly[poly(N-vinyl-carbazole)] films

In this paper, poly[poly(N-vinyl-carbazole)] (PPVK) films electrodeposited in tetrahydrofuran (THF) containing 12 % boron trifluoride diethyl etherate (BFEE) were studied as electrode active material for supercapacitors. The morphology and thermal property were characterized by SEM, atomic force microscopy (AFM), and thermogravimetry (TG), respectively. The electrochemical capacitive behaviors of the PPVK films were also investigated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The electrochemical results showed that the specific capacitance of PPVK films in CH3CN solution was about 126 mF cm−2 at 1.5 mA cm−2 and the capacitance retention was only 14.4 % after 1000 cycles. It was exciting to improve the specific capacitance up to 169.3 mF cm−2 at 1.5 mA cm−2 and to make the cyclic stability increase to 81.8 % capacitance retention after 5000 cycles when the equivalent BFEE was added into the CH3CN solution containing 0.05 M Bu4NBF4 electrolyte. These results clearly demonstrated that BFEE was an efficient promoter for the enhancement of the capacitance performance of PPVK films. Therefore, with the help of BFEE electrolyte, the PPVK films have potential application as capacitive materials in high-performance energy storage devices.

Synthesis of novel high primary hydroxyl functionality polyol from sunflower oil using thiol-yne reaction and their application in polyurethane coating

In this study, novel bio-based polyurethanes that have characteristics of both thermosets and thermoplastics were prepared. The polyol functionalized by a high number of hydroxyl groups was synthesized and its application in polyurethanes, a well-known polymer in coating industry, was investigated. Sunflower oil was decorated for the first time with propargyl groups by ring-opening of epoxied groups using boron trifluoride diethyl etherate as catalyst. The polyol is obtained by photochemical thiol-yne coupling functionalization of propargylated oil in presence of mercaptoethanol in an economical, and environmental friendly procedure. The chemical structure of this sunflower based polyol and its intermediates were determined by 1H NMR and FT-IR analysis. A series of polyurethanes containing various NCO/OH molar ratio were synthesized by a one-step procedure. The properties of the polyurethanes were studied by performing tensile testing, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). A facile and green method for the synthesis of bio-based polyurethanes and their application as a transparent coating made them exponentially advantageous.

One‐Pot Synthesis of N‐tert‐Butylsulfinylimines and Homoallylamine Derivatives from Epoxides

The reaction of epoxides with tert‐butanesulfinamide in the presence of a Lewis acid, such as erbium triflate or boron trifluoride–diethyl ether, in THF as solvent, under microwave or thermal activation, produces N‐tert‐butylsulfinylimines in reasonable yields. Aromatic and gem‐disubstituted and trisubstituted alkyl epoxides performed better than mono‐alkyl‐substituted compounds. After imine formation, a subsequent indium‐promoted allylation can be carried out in the same reaction flask in a single synthetic operation leading to homoallylamine derivatives with generally high yields.

Depolymerization of end-of-life poly(dimethylsilazane) with boron trifluoride diethyl etherate to produce difluorodimethylsilane as useful commodity

GRAPHICAL ABSTRACT

One step electrosynthesis of conjugated polymers thin film for Fe3+ detection and its potential application

Poly(9-fluorenecarboxylic acid) (PFCA) thin film was successfully fabricated onto the surface of indium tin oxide glass by one-step electropolymerization of commercially available 9-fluorenecarboxylic acid in boron trifluoride diethyl etherate. Meanwhile, PFCA thin film could specifically recognize Fe3+. Fe3+ was generated by the oxidization of Fe2+ in the presence of H2O2 that was produced by biochemical reactions and resulted in fluorescence quenching of PFCA thin film. Furthermore, a sensing platform was designed for highly selective fluorescent detection of glucose. The qualitative and quantitative analysis of Fe3+, H2O2 and glucose with detection limits of 1μM, 2.9μM and 3.4μM respectively could be implemented by a simple, cost-effective, reusable, practical and multi-functional PFCA thin film. The fabricated PFCA-based chemo/bio sensing film for fluorescent detection of Fe3+ in rice sample or glucose in serum sample was assessed. Satisfactory results indicate that this work will provide not only a new strategy for fluorescent detection of important substances in agricultural science, but also significant theoretical guidance and important reference value for the practical application and development of multi-functional sensing device.

Optimization of the new technology for manufacturing γ-polyoxymethylene

A new technology of manufacturing γ-polyoxymethylene (γ-POM) by the polymerization 1,3,5-trioxane in the presence of a boron trifluoride etherate aprotic catalytic agent and a methylal telogen in the medium of the non-ozone-depleting solvent toluene, with an yield exceeding the yield of γ-POM manufactured by the existing industrial technology by 30% is developed. Regression equations for the yield and weight-average particle size of γ-POM synthesized in the toluene medium were derived by means of the optimal experimental design technique. The equations were used to optimize parameters of the synthesis and obtain γ-POM with the weight-average particle size of 15 μm and the highest possible yield.

Electrochemical Treatment for Effectively Tuning Thermoelectric Properties of Free-Standing Poly(3-methylthiophene) Films.

The degree of oxidation of conducting polymers has great influence on their thermoelectric properties. Free-standing poly(3-methylthiophene) (P3MeT) films were prepared by electrochemical polymerization in boron trifluoride diethyl etherate, and the fresh films were treated electrochemically with a solution of propylene carbonate/lithium perchlorate as mediator. The conductivity of the resultant P3MeT films depends on the doping level, which is controlled by a constant potential from -0.5 to 1.4 V. The optimum electrical conductivity (78.9 S cm(-1) at 0.5 V) and a significant increase in the Seebeck coefficient (64.3 μV K(-1) at -0.5 V) are important for achieving an optimum power factor at an optimal potential. The power factor of electrochemically treated P3MeT films reached its maximum value of 4.03 μW m(-1) K(-2) at 0.5 V. Moreover, after two months, it still exhibited a value of 3.75 μW m(-1) K(-2) , and thus was more stable than pristine P3MeT due to exchange of doping ions in films under ambient conditions. This electrochemical treatment is a significant alternative method for optimizing the thermoelectric power factor of conducting polymer films.

Stereoselective synthesis of tetrahydropyran new derivatives underlain by α-allyl ketones

Decarboxylation of α-allyl-substituted acetoacetic esters afforded α-allyl ketones that were reduced with L-selectride [LiBH(s-Bu)3] in alcohols RCH(OH)CH2CH2CH=C(Me)CH2R'. The latter reacted with methyl 4-hydroxy-3-formylbenzoate and methyl orthoformate in the presence of p-toluenesulfonic acid to provide trans-tetrahydropyrano[3,2-с][1]benzopyran. In reaction of the E-isomer of alcohol Me2CHCH(OH) CH2CH2CH=C(Me)CH2CH2Ph with CF3SO3H a stereoselective cyclization occurred with the formation of 2,6-disubstituted tetrahydropyran; Prins reaction with 4-bromobenzaldehyde and salicylaldehyde in the presence of boron trifluoride etherate also proceeded stereoselectively giving a substituted tetrahydropyrano-[3,2-c][1]-benzopyran.

(18)F]tetrafluoroborate as a PET tracer for the sodium/iodide symporter: the importance of specific activity.

Background[18F]BF4−, the first 18F-labelled PET imaging agent for the sodium/iodide symporter (NIS), was produced by isotopic exchange yielding a product with limited specific activity (SA, ca. 1 GBq/μmol) posing a risk of sub-optimal target-to-background ratios (TBR) in PET images due to saturation of NIS in vivo. We sought to quantify this risk and to develop a method of production of [18F]BF4− with higher SA.MethodsA new radiosynthesis of [18F]BF4− was developed, involving reaction of [18F]F− with boron trifluoride diethyl etherate under anhydrous conditions, guided by 11B and 19F NMR studies of equilibria involving BF4− and BF3. The SA of the product was determined by ion chromatography. The IC50 of [19F]BF4− as an inhibitor of [18F]BF4− uptake was determined in vitro using HCT116-C19 human colon cancer cells expressing the human form of NIS (hNIS). The influence of [19F]BF4− dose on biodistribution in vivo was evaluated in normal mice by nanoPET imaging and ex vivo tissue counting.ResultsAn IC50 of 4.8 μΜ was found in vitro indicating a significant risk of in vivo NIS saturation at SA achieved by the isotopic exchange labelling method. In vivo thyroid and salivary gland uptake decreased significantly with [19F]BF4− doses above ca. 10 μg/kg. The new radiosynthesis gave high radiochemical purity (>99 %) and moderate yield (15 %) and improved SA (>5 GBq/μmol) from a starting activity of only 1.5 GBq.Conclusions[18F]BF4− produced at previously reported levels of SA (1 GBq/μmol) can lead to reduced uptake in NIS-expressing tissues in mice. This is much less likely in humans. The synthetic approach described provides an alternative for production of [18F]BF4− at higher SA with sufficient yield and without need for unusually high starting activity of [18F]fluoride, removing the risk of NIS saturation in vivo even in mice.Trial registrationISRCTN75827286.Electronic supplementary materialThe online version of this article (doi:10.1186/s13550-016-0188-5) contains supplementary material, which is available to authorized users.

Conversion of β-glycopyranoside to α-glycopyranoside by photo-activated radical reaction

By using carbon tetrachloride as the chloride radical and boron trifluoride etherate as the Lewis acid, the halogen-light-activated anomeric inversion of glycoside was achieved. This reaction is a novel guide to invert the glycosidic bond from a β-anomer to an α-anomer.

Expeditious and Convenient Synthesis of Polycyclic Difluoroboron Complexes of 2‐Oxoindoline‐3‐carboxamides by Tandem Reaction

AbstractN‐Aryl‐2‐cyanodiazoacetamides produce polycyclic difluoroboron 2‐oxoindoline‐3‐carboxamide complexes (up to pentacyclic conjugative and fused systems) directly and expeditiously in the presence of boron trifluoride etherate. The boron trifluoride serves as both a catalyst and reactant in the tandem reaction. The tandem reaction includes the carbene aromatic CH insertion, hydrolysis of the cyano group into an amide group, and boronation of the two amide carbonyl groups. The synthetic method features the advantages of wide substrate scope and excellent chemoselectivity.magnified image

Synthesis of N,N,O-Trisubstituted Hydroxylamines by Stepwise Reduction and Substitution of O-Acyl N,N-Disubstituted Hydroxylamines.

Diverse N,N,O-trisubstituted hydroxylamines, an under-represented group in compound collections, are readily prepared by partial reduction of N-acyloxy secondary amines with diisobutylaluminum hydride followed by acetylation and reduction of the so-formed O-acyl-N,N-disubstituted hydroxylamines with triethylsilane and boron trifluoride etherate. Use of carbon nucleophiles in the last step, including allyltributylstannane, silyl enol ethers, and 2-methylfuran, gives N,N,O-trisubstituted hydroxylamines with branching α- to the O-substituent. N,N-Disubstiuted hydroxylamines are conveniently prepared by reaction of secondary amines with dibenzoyl peroxide followed by diisobutylaluminum hydride reduction.

Novel Chiral Conducting Poly[N-(9-Fluorenylmethoxycarbonyl)-L-Alanine] (PN9FA) with Good Fluorescence Properties via Electropolymerization

ABSTRACTPoly[N-(9-fluorenylmethoxycarbonyl)-L-alanine] (PN9FA) films with good fluorescence properties and chirality were prepared electrochemically by direct anodic oxidation of N-(9-fluorenylmethoxycarbonyl)-L-alanine (N9FA) in boron trifluoride diethyletherate (BFEE). Results of FT-IR spectral measurements indicated that N9FA was probably polymerized through the coupling at the C (2) and C (7) positions. Results of electrochemical measurements of PN9FA showed good redox activity and stability. The fluorescence spectra indicated that PN9FA films were blue-light emitters. In addition, the structures and properties of the monomer and the polymers were characterized and evaluated with cyclic voltammograms (CVs), 1H-NMR, UV–vis spectra (UV), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM).

A novel boron–silicon–alkynyl hybrid copolymer

A novel boron–silicon–alkynyl hybrid copolymer (BSD) was synthesized by condensation polymerization of 1,3-diethynylbenzene with dichloromethylsilane and boron trifluoride etherate. Fourier transform infrared and 1H-, 13C-, and 29Si-nuclear magnetic resonance spectroscopies were used to confirm the structures of the copolymers. Thermogravimetric analysis and differential scanning calorimetry showed that the polymer exhibited excellent heat resistance and thermo-oxidative stabilities under nitrogen and air. The cure cross-linking reaction mechanisms of the BSD were related to Diels–Alder intermolecular cyclization involving two C≡C bonds and hydrosilylation reaction between Si–H and C≡C bonds. The [Formula: see text] of the BSD was above 591°C and 530°C under nitrogen and air, respectively. The residues at 1000°C were above 88% under nitrogen and 25% in air. X-ray diffraction was used to study the formation of ceramics. The precursor for ceramics (β-SiC, α-SiC, and B4C) was formed at 1600°C under an argon atmosphere. The thermo-oxidative stabilities of the copolymers were attributed to the existing organic groups of alkynyl and inorganic elements of silicon and boron.