Boron Trifluoride Complexes Research Articles

The effect of boron trifluoride complex on the preparation of mesophase pitch from FCC decant oil fractions with different compositions and molecular structures

The boron trifluoride complex catalyst can effectively facilitate the development of anisotropic structures in FCC decant oil (FCC-DO) through cationic polymerization reaction. However, the fractions of FCC-DO with different boiling points possess different molecular compositions and aromatic nuclei configurations. In this study, FCC-DO is separated into light fraction, middle fraction, and heavy fraction by vacuum distillation. The different carbonization reaction pathways and reactivity were systematically investigated for three narrow fractions with no or 5 wt% addition of boron trifluoride complex catalyst. The results show that the heavy fraction is dominated by 4 and 5 plus ring aromatics with short side chains and methylene-bridged bonds. The catalyst showed excellent catalytic activity for the heavy fraction, the resulting product (MP-HF-5) possessing a softening point of 307 °C and 3.06 wt% methylene-bridged hydrogen at 95.3 wt% mesophase content. However, the catalyst slightly facilitated the development of anisotropic structures in the middle fraction (rich in 3 and 4 rings aromatics with naphthenic structures), which provided mesogen molecules during the FCC-DO carbonization reaction. Finally, the 1 ∼ 3 ring aromatics with long alkyl side chains are mainly present in the light fractions. The catalyst did not show obvious catalytic activity for the light fraction, in contrast, the oxygen-containing functional groups in the catalyst reacted with the aromatic molecule to form a disordered oxidative cross-linked structure, resulting in an almost completely isotropic structure of MP-LF-5.

Boron Trifluoride‐Mediated Synthesis of Oxazole N‐oxides

AbstractA new synthetic protocol for the preparation of oxazole N‐oxides in the form of stable boron trifluoride complexes has been developed. It is based on the condensation of α‐diketone monooximes with an appropriate aldehyde component in the presence of an equimolar amount of boron trifluoride. The method opens access to a broad scope of derivatives including previously unknown 2‐unsubstituted oxazole N‐oxides. Its abilities were demonstrated via the synthesis of 25 diverse oxazole derivatives in 14–89 % yields.

Influence of boron trifluoride complex addition on structure and composition of mesophase pitch from FCC decant oil via two-stage thermotreatment

In order to optimize the molecular structure and composition distribution of mesophase pitch, the two-stage thermotreatment process preparation using boron trifluoride ethyl valerate complex as catalyst was investigated. During the two-stage thermotreatment, the cationic polymerization initiated by catalytic polycondensation made carbonaceous microcrystalline molecules contain more semi-rigid structures, while parts of alkyl side chains and naphthenic structures were retained. Subsequently, the mesophase pitch was rapidly induced to form by removing non-mesogens and enriching sufficient concentrations of mesogens in the vacuum polycondensation stage. The results showed that the two-stage thermotreatment process could change the chemical structure of the aromatic nucleus and obtain a suitable softening point (283 °C) at 100% anisotropic content. The mesophase pitch with 5 wt% catalyst addition (MP-5) had high content of methylene structure (HF = 3.18 wt%), naphthenic structure (HN = 3.45 wt%) and fusible/soluble TI-PS sub-fraction (28.07 wt%). In addition, MP-5 also possessed high aromaticity (fa = 0.90) and stacking order (Lc = 37.48 Å, n = 11.70). Unfortunately, an increase in the oxygen-containing groups was accompanied when the catalyst content reached to 10 wt%, which disrupted the aromatic lamellae parallel stacking structure of the mesophase pitch due to steric hindrance, resulting in more isotropic structures in the product.

The mechanism of direct reductive amination of aldehyde and amine with formic acid catalyzed by boron trifluoride complexes: insights from a DFT study

A volcano diagram of BF3 catalytic species and their activities was proposed for the DRA of aldehyde and amine with formic acid.

The structural, vibrational and electronic properties of the triel-bonded complexes of boron trifluoride with some cyclic ethers – An ab initio study

The properties (molecular structures, vibrational spectra and electronic distributions) of the triel-bonded complexes of boron trifluoride with the cyclic ethers oxirane, oxetane, tetrahydrofuran and tetrahydropyran have been computed. The calculations were carried out ab initio using the Gaussian 16 program at the second order level of Møller-Plesset perturbation theory (MP2) and with Dunning’s augmented correlation-consistent polarized valence triple-zeta basis sets (aug-cc-pVTZ). The results indicate that, with the exception of the oxirane complex, the interaction energies, the bond length and angle changes and the perturbations of the BF3 fragment vibrational wavenumbers are remarkably invariant to the ring size of the base. The unique position of the oxirane complex is associated with the extent of ring strain in the monomer relative to those of the other three bases.

Development of optical sensor for water in acetonitrile based on propeller-structured BODIPY-type pyridine-boron trifluoride complex.

A propeller-structured 3,5,8-trithienyl-BODIPY-type pyridine–boron trifluoride complex, ST-3-BF3, which has three units of 2-(pyridin-4-yl)-3-(thiophen-2-yl)acrylonitrile at the 3-, 5-, and 8-positions on the BODIPY skeleton, was designed and developed as an intramolecular charge transfer (ICT)-type optical sensor for the detection of a trace amount of water in acetonitrile. The characterization of ST-3-BF3 was successfully determined by FTIR, 1H and 11B NMR measurements, high-resolution mass spectrometry (HRMS) analysis, thermogravimetry-differential thermal analysis (TG-DTA), photoabsorption and fluorescence spectral measurements, and density functional theory (DFT) calculations. ST-3-BF3 showed a broad photoabsorption band in the range of 600 to 800 nm, which is assigned to the S0 → S1 transition of the BODIPY skeleton with the expanded π-conjugated system over the 2-(pyridin-4-yl)-3-(thiophen-2-yl)acrylonitrile units at the 3-, 5-, and 8-positions onto the BODIPY core. In addition, a photoabsorption band was also observed in the range of 300 to 550 nm, which can be assigned to the ICT band between the 2-(pyridin-4-yl)-3-(thiophen-2-yl)acrylonitrile units at 3-, 5-, and 8-positions and the BODIPY core. ST-3-BF3 exhibited a characteristic fluorescence band originating from the BODIPY skeleton at around 730 nm. It was found that by addition of a trace amount of water to the acetonitrile solution of ST-3-BF3, the photoabsorption band at around 415 nm and the fluorescence band at around 730 nm increased linearly as a function of the water content below only 0.2 wt%, which could be ascribed to the change in the ICT characteristics due to the dissociation of ST-3-BF3 into ST-3 by water molecules. Thus, this work demonstrated that the 3,5,8-trithienyl-BODIPY-type pyridine–boron trifluoride complex can act as a highly-sensitive optical sensor for the detection of a trace amount of water in acetonitrile.

Mechanism of the curing of epoxy by carboxylic acids and their anhydrides in the presence of amine–boron trifluoride complexes

Mechanism of the curing of epoxy by carboxylic acids and their anhydrides in the presence of amine–boron trifluoride complexes

Molecular Complexes of Boron Trifluoride with some Formyl Compounds, HCOX (X = H, CH3, NH2, OH, F): Effect of Substitution, and Extension to X = Li, BeH and BH2

The complexes formed between boron trifluoride and formaldehyde, acetaldehyde, formamide, formic acid and formyl fluoride have been studied by means of ab initio calculations at the second order level of Moller-Plesset perturbation theory (MP2), using Dunning’s aug-cc-pVTZ basis sets. The structures, the interaction energies, the perturbations of the vibrational spectra and the charge transfers occurring on complexation, both of the BF3 and of the base moieties, have been determined and the variations in these properties have been rationalized in relation to the nature of the X fragments (X = H, CH3, NH2, OH, F). The calculations have been extended to include the putative complexes between BF3 and the presently unknown compounds HCOLi, HCOBeH and HCOBH2, in order to complete the range of formyl compound bases with heteroatoms across the whole of the first row of the periodic table.Keywords: Ab initio calculations, boron trifluoride, molecular complexes, structures, energies, vibrational spectra

A colorimetric and fluorescent sensor for water in acetonitrile based on intramolecular charge transfer: D-(π-A)2-type pyridine-boron trifluoride complex.

A D-(π-A)2-type pyridine-boron trifluoride complex composed of a carbazole skeleton and two pyridine-boron trifluoride units was designed and developed as a colorimetric and fluorescent sensor based on intramolecular charge transfer (ICT) for the detection of water over a wide range from low water content to high water content in solvents.

A Stable N-Annulated Perylene-Bridged Bisphenoxyl Diradicaloid and the Corresponding Boron Trifluoride Complex.

Organic π-extended radicals display unique electronic structures, and could be used as promising functional materials. However, design and synthesis of stable radicals are challenging for chemists due to their high reactivity. In this work, we synthesized a stable N-annulated perylene-bridged bisphenoxyl diradicaloid, and its complex with Lewis acid boron trifluoride. Their ground-state geometric and electronic structures were systematically studied by various experimental methods, including X-ray crystallographic analysis, variable-temperature NMR spectroscopy, electron-spin resonance spectroscopy (ESR), and superconducting quantum interference device (SQUID) measurements, supported by density functional theory. Both were observed as open-shell singlet diradicaloids in the ground state. The bisphenoxyl diradicaloid demonstrated string features of strong near-infrared (NIR) absorption, closely packed π-dimer structure in crystals, amphoteric redox behavior with a small HOMO-LUMO energy band gap, and a rather small singlet-triplet gap, whereas the complex showed very different photophysical, electrochemical, and magnetic properties. Our studies provide an efficient method of making stable diradicaloids by Lewis acid/base complexation.

The properties of the Lewis acid-base complexes of boron trifluoride with some carbon dioxide analogues. An ab initio study

The properties of nine binary Lewis acid-base complexes, formed between boron trifluoride, on the one hand, and the carbon dioxide analogues XCY (X, Y = O, S, Se) on the other, have been investigated by means of ab initio calculations. The properties of most interest are the structures, the interaction energies, the vibrational spectra and the natural orbital population changes. The structures of the complexes bound through either a sulphur or a selenium atom are remarkably similar, and feature a FB … XC fragment in a trans arrangement, with FB … X and B … XC angles close to 90°. The adducts bound through oxygen have quite different structures, with a B … OC angle close to 150° in the case of BF3·OCO and with linear B … OCS and B … OCSe moieties in the other two cases. The binding energies of all nine complexes span a very narrow range, and are all less than 10 kJ mol−1. The changes of the intramolecular BF, XC and CY bond lengths are small, but they vary in a systematic way with the strength of interaction. The wavenumber shifts of the modes of the BF3 and XCY fragments are also fairly insignificant, except for the symmetric bending mode of the BF3 molecule, where the shifts are found to be in the range from −20 to −40 cm−1. The similarities and differences in the properties of the three families of adducts have been rationalized by reference to the redistribution of the natural orbital populations resulting from complex formation.

Determination of boron trifluoride in boron trifluoride complex by fluoride ion selective electrode

A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain pH value was limited and hardly related to F-concentration and boric acid. It is better to control pH value below 11.5 and the aluminum concentration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80 °C for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

ChemInform Abstract: Polyvinylpolypyrrolidone‐Supported Boron Trifluoride: A Mild and Efficient Catalyst for the Synthesis of 1,8‐Dioxooctahydroxanthenes and 1,8‐Dioxodecahydroacridines

Abstractvia simple multicomponent reactions

Synthesis of 1,4- and 1,5-Diaryl-1H-Imidazoles

A simple method for the synthesis of 1,4- and 1,5-diarylimidazoles has been developed. The method is based on the condensation of appropriate α-diketone monooxime with aromatic amines and formaldehyde in the presence of boron trifluoride etherate leading to the formation of stable boron trifluoride complexes of imidazole N-oxides. Further reduction of these complexes led to the formation of corresponding imidazoles.

The molecular complexes of boron trifluoride with nitrosyl fluoride and nitrosyl chloride. Ion-pair formation

The electron donor–acceptor complexes formed between boron trifluoride and the nitrosyl halides ONF and ONCl have been studied by means of ab initio molecular orbital theory at the second order level of Møller–Plesset perturbation theory and with Dunning’s augmented correlation-consistent polarized valence triple-zeta basis set. The focus of the calculations was on the structures, interaction energies and vibrational spectra of the complexes. A variety of trial structures were examined, with electron donation occurring from the oxygen, nitrogen and halogen atoms, in an attempt to establish the most favorable site for interaction. In addition, a number of rotational isomers for each adduct were investigated. It was found that, in both cases, the halogen atom was the preferred donor atom. Several of the optimized structures suggested that the formation of ion pairs would lead to stable complexes, and four separate ion-pair structures were included among the possible associated species for each combination of interacting molecules. In those cases the computed spectra were more consistent with those of the NO+ and BF4− or BClF3− ions than of the corresponding neutral components. The relative stabilities of the two families of complexes have been rationalized and some differences between the properties of the ONF and ONCl adducts have been observed and explained.

ChemInform Abstract: Regioselective Synthesis of 2‐Unsubstituted 1‐Aryl‐4‐ and 1‐Aryl‐5‐acylimidazoles.

Abstract An efficient and simple method for the synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles has been developed. It consists in the condensation of α-diketone monooximes with aromatic amines and formaldehyde on the presence of boron trifluoride etherate, leading to the formation of stable boron trifluoride complexes of N-oxides. Further reduction of these complexes led to the corresponding imidazoles. This method permits broad variations of substituents in the aryl part of these compounds.

Polyvinylpolypyrrolidone-supported boron trifluoride: a mild and efficient catalyst for the synthesis of 1,8-dioxooctahydroxanthenes and 1,8-dioxodecahydroacridines

Polyvinylpolypyrrolidone-supported boron trifluoride has been studied for the synthesis of 1,8-dioxooctahydroxanthenes and 1,8-dioxodecahydroacridines. The reaction proceeded via condensation of: (1) aromatic aldehydes (1 eq.) and 5,5-dimethyl-1,3-cyclohexanedione (2 eq.) in acetonitrile at room temperature, (2) aromatic aldehydes (1 eq.), 5,5-dimethyl-1,3-cyclohexanedione (2 eq.), and aromatic amines (1 eq.) in acetonitrile at 80 °C in the presence of polyvinylpolypyrrolidone-supported boron trifluoride. This procedure cleanly converted a variety of aryl aldehydes with different substituent groups at ortho, meta, or para positions to the corresponding products. Convenience and efficiency, an easy work-up procedure, high yield, and simple preparation of the catalyst are some advantages of this method. In addition, the polyvinylpolypyrrolidone-supported boron trifluoride complex is a high loaded Lewis acid, which is stable, easy to handle, and retains effective activity after several months of storage.

Regioselective synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles

An efficient and simple method for the synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles has been developed. It consists in the condensation of α-diketone monooximes with aromatic amines and formaldehyde on the presence of boron trifluoride etherate, leading to the formation of stable boron trifluoride complexes of N-oxides. Further reduction of these complexes led to the corresponding imidazoles. This method permits broad variations of substituents in the aryl part of these compounds.

The vibrational spectra of the boron halides and their molecular complexes. Part 13. Ab initio studies of the complexes of boron trifluoride with formaldehyde and some of its analogs

AbstractThe structure, the interaction energy, and the vibrational spectrum of the electron donor–acceptor complex formed between boron trifluoride, as a Lewis acid, and formaldehyde, as a Lewis base, have been determined by means of ab initio calculations at the second‐order level of Møller–Plesset perturbation theory, using a triple‐zeta basis set with polarization and diffuse functions on all atoms. The object was to examine the differences in the properties of the complexes formed between boron trifluoride and an oxygen base containing oxygen in the sp2 hybrid state with those of some sp3 oxygen bases studied earlier. The investigation has then been extended to include the related bases thioformaldehyde and methanimine, to assess the effect of substituting the oxygen atom by a sulphur atom or an imino group. A further range of formaldehyde analogs, containing one and two methyl groups, one and two fluorine atoms, and one methyl group and one fluorine atom, has also been included. The preferred structure of each complex has been identified. The computed data have been compared, and the complex properties correlated with some relevant physical properties of the bases. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012

Synthesis and study of boron trifluoride-based catalytic complex participating in hexafluoropropylene sulfotrioxation

Catalytic complexes of boron trifluoride and sulfuric anhydride were experimentally detected and studied by the 19F NMR method.