Boron Trifluoride Complexes Research Articles

Donor-acceptor complexes of linear oligopyrroles with boron trifluoride. Spectral studies and quantum-chemical simulation

Intermediate products of synthesis of the boron trifluoride complexes with linear oligopyrroles are found. By means of electronic spectroscopy it was shown that the reaction of linear oligopyrroles with boron trifluoride in solutions resulted in the formation of stable donor-acceptor complexes. Their composition was established and the formation constants were evaluated. It was shown that transformation of these complexes in the corresponding borofluoride complexes is possible only while boiling the reaction mixture. By means of quantum-chemical methods the structural and energy parameters of the donor-acceptor complexes under study were calculated.

Homo- and copolymers of 3-tosyloxymethyl-3-methyl oxetane (TMMO) as precursors to energetic azido polymers

AbstractPoly(3-azidomethyl-3-methyloxetane) and its copolymers with 3,3- bis(azidomethyl)oxetane were synthesized by cationic polymerization from 3- tosyloxymethyl-3-methyl oxetane and 3,3-bis(bromomethyl)oxetane, using a polyol as initiator and boron trifluoride complex as catalyst, followed by azidation. The final objective is the synthesis of an energetic binder to be used for rocket propellants and therefore the effects of different initiator/catalyst systems on important properties, like, i.e., the molecular weight distribution and the functionality of the polymer, were investigated. It was found that, even though both the operating conditions and the catalytic system were chosen in order to grant the living character of the polymerization, the latter seems to be prevalently driven by an “active chain end” mechanism. In particular, this may lead to the undesired formation of a small quantity of oligomers and to the presence of non-hydroxylic chain-end functionalities. Nevertheless, the average number of OH groups can be strictly controlled when boron trifluoride tetrahydrofuranate is used as catalyst.

The vibrational spectra of the boron halides and their molecular complexes. Part 12: The complexes of boron trifluoride with methyl fluoride and methyl chloride. An ab initio study

The properties of the molecular complexes formed between boron trifluoride and the methyl halides, CH 3F and CH 3Cl, have been computed by means of a series of ab initio calculations, at the second order level of Møller–Plesset perturbation theory, using a triple-zeta Gaussian basis set with polarization and diffuse functions on all atoms. We have determined the structures and interaction energies of these two adducts, and compared the results with earlier calculations on analogous complexes of boron trifluoride with water, hydrogen sulphide, ammonia and phosphine and their partially- and fully-methylated derivatives, and with hydrogen fluoride and hydrogen chloride. The results show a strong correlation with the basic properties of the partner molecules. The vibrational spectra of the complexes have also been determined, and similar correlations have been found between the perturbations of the BF 3 spectra in the complexes and the inter-monomer stretching force constants, and the interaction energies.

Vibrational Spectra of the Boron Halides and Their Molecular Complexes. Part 11. Complexes of Boron Trifluoride with Phosphine and Its Methyl Derivatives. An ab Initio Study

Ab initio calculations, at the second-order level of Møller-Plesset perturbation theory, using a triple-zeta Gaussian basis set with polarization and diffuse functions on all atoms, have been carried out on the donor-acceptor complexes of boron trifluoride with phosphine and its mono-, di-, and trimethyl derivatives. The structures, interaction energies, and vibrational spectra of the complexes were determined. The preferred conformer was found to be the staggered species in each case. The computed data were compared with those for some similar complexes containing boron trifluoride and a series of related oxygen, sulfur, and nitrogen bases, and the effect of successive methyl substitution in each series was investigated.

The vibrational spectra of the boron halides and their molecular complexes: Part 10. The complexes of boron trifluoride with ammonia and its methyl derivatives. An ab initio study

Ab initio calculations, at the level of second order Møller–Plesset perturbation theory, and using a triple-zeta Gaussian basis set with polarization and diffuse functions on all atoms, have been carried out on the donor–acceptor complexes of boron trifluoride with ammonia and its mono-, di- and trimethyl derivatives. The structures, interaction energies and vibrational spectra of the complexes have been determined. An eclipsed and a staggered conformer have been examined for each complex, and the preferred conformer was found to be the staggered species in each case. The computed data have been compared with those for some similar complexes containing boron trifluoride and a series of oxygen and sulphur electron donors (water, hydrogen sulphide, methanol, methanethiol, dimethyl ether and dimethyl sulphide) and the effect of successive methyl substitution in all three series has been investigated.

Accelerated Silane Water‐Crosslinking Kinetics of Ethylene–Propylene Copolymer by Boron Trifluoride Complexes

AbstractThe hydrolysis and overall water‐crosslinking kinetics of vinyltrimethoxysilane‐grafted ethylene–propylene copolymer (EPR‐g‐VTMS) containing boron trifluoride monoethylamine complex (BF3–MEA), boron trifluoride methanol complex (BF3–MeOH), or di‐n‐butyltin(II) dilaurate (DBTL) as a silane‐crosslinking catalyst was followed by ATR‐FT‐IR and measuring the gel fraction, respectively. Kinetics results by ATR‐FT‐IR technique showed that using BF3–MEA provided much lower activation energy for the hydrolysis reactions than that of DBTL; however, BF3–MeOH had little catalytic effect on both the hydrolysis and overall water‐crosslink reaction of EPR‐g‐VTMS. We propose that the actual catalytic effect of ethylamine molecule dissociated from BF3–MEA results in the displacement of SiOCH3 groups via an SN2‐Si mechanism.magnified image

The vibrational spectra of the boron halides and their molecular complexes. Part 9. Ab initio studies of the complexes of boron trifluoride with methanol, methanethiol and some related bases

The structures, interaction energies and vibrational spectra of the electron donor-acceptor complexes formed between boron trifluoride, as Lewis acid, and methanol and methanethiol, as Lewis bases, have been determined by means of ab initio calculations at the level of second order Møller–Plesset perturbation theory, using a triple-zeta Gaussian basis set with polarization and diffuse functions on all atoms. Two conformers, an eclipsed and a staggered species, have been examined for each complex, and the preferred conformer identified in each case. The computed data have been compared with those for some related complexes containing boron trifluoride and other oxygen and sulphur electron donors (water, hydrogen sulphide, dimethyl ether and dimethyl sulphide).

Curing of mixtures of epoxy resins and 4‐methyl‐1,3‐dioxolan‐2‐one with several initiators

AbstractDiglycidyl ether of bisphenol A or 3,4‐epoxycyclohexylmethyl 3,4‐epoxycyclohexane carboxylate were mixed with different proportions of 4‐methyl‐1,3‐dioxolan‐2‐one and cured using lanthanide triflates as initiators. In order to compare the materials obtained, conventional initiators such as boron trifluoride complexes and N,N‐dimethylaminopyridine were also tested. The curing process was followed by differential scanning calorimetry (DSC) and Fourier transform IR in attenuated total reflectance mode. This technique proved that the carbonate accelerates the curing process because it helps to form the active initiating species, although it was not chemically incorporated into the network and remained entrapped in the material. The DSC kinetic study was also reported. © 2006 Wiley Periodicals Inc. J Appl Polym Sci 102: 2086–2093, 2006

Conformational preferences of the structures, and energetics of the molecular complexes of boron trifluoride with some hydrogen halides, halogens and interhalogens

The optimized structures and interaction energies of a number of complexes of boron trifluoride, as electron acceptor, with some halogen bases, as electron donors, have been determined by means of ab initio molecular orbital calculations. The bases include the hydrogen halides (HF, HCl and HBr), the halogens (F 2, Cl 2 and Br 2), and the diatomic interhalogens (ClF, BrF and BrCl). In each case the major interaction takes place through a halogen atom of the base and the boron atom of BF 3. In the complexes with the hydrogen halides the preferred conformation is the eclipsed species, while for the other two series the staggered conformer is usually more stable. The strengths of interaction correlate with some of the properties of the bases, such as the gas phase basicities, the ionization energies, the polarizabilities, and the dipole and quadrupole moments, where appropriate.

FTIR studies of the CH3CN–BF3 complex in solid Ar, N2, and Xe: Matrix effects on vibrational spectra

FTIR spectra of the four isotopically substituted 1:1 complexes of acetonitrile and boron trifluoride were recorded in Ar, N2 and Xe matrices. In Ar, previously unreported three vibrational modes of the complex were clearly observed. Several significant vibrational bands were also observed in N2 and Xe. The observed frequency shifts on complexation, Δν, were qualitatively in good agreement with the computational results, which were calculated at the B3LYP/6-311++G(d,p) level using the optimized geometry of the C3v eclipsed conformation. The observed magnitudes of Δν for most of the complex bands were larger than the calculated values. The BF3 symmetric deformation mode is an exception. The observed frequency shits for this mode were smaller than the calculated values, especially in N2. This suggests that even an inert matrix can significantly affect the vibrational spectrum of the complex.

An ab initio and cryospectroscopic study of the hydrogen chloride and boron trifluoride complexes of cyclopropene

Mid-infrared spectra of cyclopropene ( c-C 3H 4) mixtures with HCl or BF 3, dissolved in liquefied argon and in liquefied nitrogen have been examined. Evidence was found for the formation of two different isomers of the 1:1 complexes: a π-type complex in which the interaction occurs with the π-bond of cyclopropene, and a σ-type complex in which the electron acceptors interact with one of the C C single bonds. At lower temperatures, indications for the formation of a 1:2 chain-type complex were found. Using spectra recorded between 90 and 124 K in liquid argon, the complexation enthalpies for the π- and σ-complexes with HCl were determined to be −8.8(3) and −7.9(3) kJ mol −1, respectively. For the π-complex with BF 3 a value of −7.4(3) kJ mol −1 was found. Structural and spectral information on the 1:1 complexes was obtained from B3LYP/6-311++G(d,p) and MP2(FC)/6-31+G(d) calculations. Using Free Energy Perturbation Monte Carlo simulations to calculate the solvent influences, and statistical thermodynamics to account for zero-point vibrational and thermal contributions, the solution enthalpies were transformed into complexation energies with values of −15.5(6) and −13.8(8) kJ mol −1 for the π- and σ-isomers of c-C 3H 4·HCl, respectively, and of −12.7(8) kJ mol −1 for the π-type BF 3 complex.

Influence of the type of epoxy hardener on the structure and properties of interpenetrated vinyl ester/epoxy resins

AbstractThe morphology–toughness relationship of vinyl ester/cycloaliphatic epoxy hybrid resins of interpenetrating network (IPN) structures was studied as a function of the epoxy hardening. The epoxy was crosslinked via polyaddition reactions (with aliphatic and cycloaliphatic diamines), cationic homopolymerization (via a boron trifluoride complex), and maleic anhydride. Maleic anhydride worked as a dual‐phase crosslinking agent by favoring the formation of a grafted IPN structure between the vinyl ester and epoxy. The type of epoxy hardener strongly affected the IPN morphology and toughness. The toughness was assessed by linear elastic fracture mechanics, which determined the fracture toughness and energy. The more compact the IPN structure was, the lower the fracture energy was of the interpenetrated vinyl ester/epoxy formulations. This resulted in the following toughness ranking: aliphatic diamine > cycloaliphatic diamine ≥ boron trifluoride complex > maleic anhydride. For IPN characterization, the width of the entangling bands and the surface roughness parameters were considered. Their values were deduced from atomic force microscopy scans taken on ion‐etched surfaces. More compact, less rough IPN‐structured resins possessed lower toughness parameters than less compact, rougher structured ones. The latter were less compatible according to dynamic mechanical thermal and thermogravimetric analyses. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5471–5481, 2004

A New Method for the Synthesis of Bishydroperoxides Based on a Reaction of Ketals with Hydrogen Peroxide Catalyzed by Boron Trifluoride Complexes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

New Synthetic Capabilities of Sulfonium Salts.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A new method for the synthesis of bishydroperoxides based on a reaction of ketals with hydrogen peroxide catalyzed by boron trifluoride complexes

A reaction of cycloalkanone, alkanone and alkyl aryl ketone ketals with H 2O 2 catalyzed by boron trifluoride etherate and boron trifluoride–methanol complexes was studied. A new versatile method for the synthesis of bishydroperoxides and their derivatives, viz. 1,1′-dihydroperoxyperoxides and 1,2,4,5-tetraoxacyclohexanes, was developed based on this reaction.

The Fourier transform infrared spectra of the complexes of boron trifluoride with dimethyl ether and dimethyl sulphide in cryogenic matrices

The infrared spectra of boron trifluoride, co-condensed with dimethyl ether and with dimethyl sulphide in nitrogen and argon matrices at ca. 17 K, have been recorded. The spectra are consistent with the formation of 1:1 electron donor–acceptor molecular complexes, with donation occurring from the orbitals of the ether or the sulphide dominated by the oxygen or sulphur lone pairs to the orbital of boron trifluoride correlating with the empty axial 2p atomic orbital of boron. The wavenumber shifts of the respective monomer absorption bands have been determined in each matrix and correlated with the physical properties of the bases. The spectra may be rationalized by referring to the results of some molecular orbital calculations on these systems.

New synthetic capabilities of sulfonium salts

The review summarizes published data on the synthesis and reactivity of new functionally substituted sulfonium salts: dimethyl(trifluoromethylsulfonyloxy)sulfonium trifluoromethanesulfonate, dimethyl(trifluoromethylsulfonyl)sulfonium trifluoromethanesulfonate, various disulfonium dications, dimethyl sulfidesulfur trioxide complex, acyl(dimethyl)sulfonium salts, dimethyl(trifluoroacetyl)sulfonium salts, and boron trifluoride complexes with alkylthio-substituted acyl fluorides as intramolecular analogs of acylsulfonium salts. A theoretical approach is described, which explains electrophilic reactivity of sulfonium salts.

Determination of cutin-bound residues of chlorothalonil by immunoassay.

An indirect competitive enzyme-linked immunosorbent assay (ELISA) was used to determine photochemically cutin-bound residues of chlorothalonil in enzymatically isolated tomato and apple fruit cuticles. The samples were spiked, irradiated, exhaustively extracted, and depolymerized with boron trifluoride complex resulting in a soluble depolymerisate. With this procedure, the ELISA could be calibrated with free target molecules for the quantification of originally bound chlorothalonil residues. In fruit cuticles that were irradiated for 8 h by simulated sunlight, 0.030 and 0.068 mg/g photoinduced cutin-bound residues of wax-free cuticles (calculated as chlorothalonil) were determined for tomatoes and apples, respectively. For the used antibody mAb chl. 4/11, cross-reactivities with derivatives of chlorothalonil simulating different types of cuticle-bound residues are given and discussed.

ChemInform Abstract: Synthetic Utility and Mechanistic Implications of the Fries Rearrangement of Hydroquinone Diesters in Boron Trifluoride Complexes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Vibrational spectra and relative stabilities of the van der Waals complexes of boron trifluoride with cis-2-butene, trans-2-butene and 2-methyl propene

The mid-infrared spectra (4000–400cm−1) of mixtures of BF3 with cis-2-butene, trans-2-butene and 2-methylpropene, dissolved in liquefied argon (88–127K), have been investigated. In all spectra, evidence was found for the formation of a 1:1 van der Waals complex, while at higher concentrations of BF3 weak bands indicating the presence of a 1:2 complex were also observed. Using spectra recorded at different temperatures, the complexation enthalpies ΔH° for cis-2-butene·BF3, trans-2-butene·BF3 and 2-methylpropene·BF3 were determined to be −12.5(2), −12.4(2) and 12.7(2)kJmol−1, respectively. For all 1:1 complexes studied, the equilibrium geometry and the vibrational frequencies were obtained from density functional calculations at the B3LYP/6-311++G(d,p) level. Using statistical thermodynamics to account for the zero-point vibrational and thermal contributions, the complexation enthalpies of the 1:1 complexes were transformed into complexation energies ΔE. The resulting values, −14.5(4), −14.9(5) and −14.8(5)kJmol−1, respectively, are compared with the values predicted at the B3LYP/6-311++G(d,p) and the BSSE corrected MP2/6-311++G(3df,2pd)//B3LYP/6-311++G(d,p) levels.