Boron Trifluoride Etherate Research Articles

Lewis acid catalyzed cis (liquid) to trans (solid) isomerization of Jojoba oil in supercritical CO2

Isomerization of the olefin from cis to trans configuration is often a desirable reaction pathway that leads to products with different properties and chemical reactivities. In this work, we report a novel process involving the use of boron trifluoride diethyl etherate, BF3·O(C2H5)2, in supercritical CO2 that converts a compound with an isolated cis to a trans olefin in quantitative yield. No polymerization was observed. The utility of this reaction has been demonstrated by the conversion of jojoba oil (a natural wax ester, comprising a monoester of long-chain fatty acids with cis olefins) to its trans isomers. Jojoba oil is liquid at room temperature with a melting point of about 10 °C; the reacted product is a solid with a melting point of 37.6 °C (around the normal human body temperature). The simplicity of the reaction and the use of supercritical CO2 are the attractive features of this reaction.

High performance polythiophene derivative with good electrochromic and energy storage properties electrochemical synthesized in boron trifluoride diethyl etherate

In this study, novel poly(3,4-dibromothiophene) (PDBrTh) is firstly prepared through electrochemical polymerization method using boron trifluoride diethyl etherate (BF3·Et2O) as polymeric solvent. In BF3·Et2O, the electrochemical oxidation potential of 3,4-dibromothiophene is significantly reduced compared with in Acetonitrile/Tetrabutylammonium tetrafluoroborate (ACN/TBATFB) system, which provides conditions for high quality polymer preparation. The prepared PDBrTh in BF3·Et2O shows good electrochemical activity and thermal stability. The electrochromic and supercapacitive performance of the prepared PDBrTh are also studied. The color of the prepared PDBrTh can be reversibly changed between red and blue with fast response time and high optical contrast. Galvanostatic charge-discharge test shows that the prepared PDBrTh also has good electrochemical energy storage performance. The specific capacitance value of the PDBrTh can reach to 229.6 F g−1 under the current density of 1 A g−1, showing good energy storage capacity. An all-polythiophenes electrochromic supercapacitor device (ESD) is constructed by prepared PDBrTh and poly(3,4-ethylenedioxythiophene), the color of the device can change between red and dark blue. The ESD also shows good energy storage property and robust charge-discharge stability. Moreover, the ESD shows obvious color changes and corresponding light transmittance changes during the charging and discharging process, realizing intelligent visual monitoring of the energy storage state. This study shows that the prepared PDBrTh has good practical application potential in the field of intelligent wearable energy storage.

Modular-Approach Synthesis of Giant Molecule Acceptors via Lewis-Acid-Catalyzed Knoevenagel Condensation for Stable Polymer Solar Cells.

The operational stability of polymer solar cells is a critical concern with respect to the thermodynamic relaxation of acceptor-donor-acceptor (A-D-A) or A-DA'D-A structured small molecule acceptors (SMAs) within their blends with polymer donors. Giant molecule acceptors (GMAs) bearing SMAs as subunits offer a solution to this issue, while their classical synthesis via the Stille coupling suffers from low reaction efficiency and difficulty in obtaining mono-brominated SMA, rendering the approach impractical for their large-scale and low-cost preparation. In this study, we present a simple and cost-effective solution to this challenge through Lewis acid-catalyzed Knoevenagel condensation with boron trifluoride etherate (BF3∙OEt2) as catalyst. We demonstrated that the coupling of the monoaldehyde-terminated A-D-CHO unit and the methylene-based A-link-A (or its silyl enol ether counterpart) substrates can be quantitatively achieved within 30 minutes in the presence of acetic anhydride, affording a variety of GMAs connected via the flexible and conjugated linkers. The photophysical properties was fully studied, yielding a high device efficiency of over 18%. Our findings offer a promising alternative for the modular synthesis of GMAs with high yields, easier work up, and the widespread application of such methodology will undoubtedly accelerate the progress of stable polymer solar cells.

Modular‐Approach Synthesis of Giant Molecule Acceptors via Lewis‐Acid‐Catalyzed Knoevenagel Condensation for Stable Polymer Solar Cells

AbstractThe operational stability of polymer solar cells is a critical concern with respect to the thermodynamic relaxation of acceptor‐donor‐acceptor (A‐D‐A) or A‐DA'D‐A structured small‐molecule acceptors (SMAs) within their blends with polymer donors. Giant molecule acceptors (GMAs) bearing SMAs as subunits offer a solution to this issue, while their classical synthesis via the Stille coupling suffers from low reaction efficiency and difficulty in obtaining mono‐brominated SMA, rendering the approach impractical for their large‐scale and low‐cost preparation. In this study, we present a simple and cost‐effective solution to this challenge through Lewis acid‐catalyzed Knoevenagel condensation with boron trifluoride etherate (BF3 ⋅ OEt2) as catalyst. We demonstrated that the coupling of the monoaldehyde‐terminated A‐D‐CHO unit and the methylene‐based A‐link‐A (or its silyl enol ether counterpart) substrates can be quantitatively achieved within 30 minutes in the presence of acetic anhydride, affording a variety of GMAs connected via the flexible and conjugated linkers. The photophysical properties was fully studied, yielding a high device efficiency of over 18 %. Our findings offer a promising alternative for the modular synthesis of GMAs with high yields, easier work up, and the widespread application of such methodology will undoubtedly accelerate the progress of stable polymer solar cells.

Low-potential Electrosynthesis and Fluorescence Properties of Poly(9,9'-bifluorenylidene) in Boron Trifluoride Diethyl Etherate

Low-potential Electrosynthesis and Fluorescence Properties of Poly(9,9'-bifluorenylidene) in Boron Trifluoride Diethyl Etherate

Acid‐catalyzed One Pot Synthesis of Thiazolo[4,5‐b]indolamines from α‐Diazoimidamides and Thioureas

AbstractA novel synthetic method for the formation of thiazolo[4,5‐b]indol‐2‐amines from α‐diazoimidamides and mono‐substituted thioureas in the presence of a catalytic amount of boron trifluoride etherate and camphorsulfonic acid under mild conditions was demonstrated. This methodology has a wide‐ranging scope of α‐diazoimidamides and mono‐substituted thioureas, amenable for upscaling experiments and further transformation.

Convenient Preparation of <i>tert</i>-Butyl Amino Acid Esters from <i>tert</i>-Butanol

A preparation of tert-butyl esters of amino acid is described that proceeds from protected amino acids and tert-butanol using anhydrous magnesium sulfate and an excess of boron trifluoride diethyl etherate as additional reagents. The method affords tert-butyl esters in good yields and a variety of amino acid side chains and substituents tolerate the reaction conditions.

Precision native polysaccharides from living polymerization of anhydrosugars.

The composition, sequence, length and type of glycosidic linkage of polysaccharides profoundly affect their biological and physical properties. However, investigation of the structure-function relationship of polysaccharides is hampered by difficulties in accessing well-defined polysaccharides in sufficient quantities. Here we report a chemical approach to precision polysaccharides with native glycosidic linkages via living cationic ring-opening polymerization of 1,6-anhydrosugars. We synthesized well-defined polysaccharides with tunable molecular weight, low dispersity and excellent regio- and stereo-selectivity using a boron trifluoride etherate catalyst and glycosyl fluoride initiators. Computational studies revealed that the reaction propagated through the monomer α-addition to the oxocarbenium and was controlled by the reversible deactivation of the propagating oxocarbenium to form the glycosyl fluoride dormant species. Our method afforded a facile and scalable pathway to multiple biologically relevant precision polysaccharides, including D-glucan, D-mannan and an unusual L-glucan. We demonstrated that catalytic depolymerization of precision polysaccharides efficiently regenerated monomers, suggesting their potential utility as a class of chemically recyclable materials with tailored thermal and mechanical properties.

Preliminary Results on Preparation and Performance of a Self-Emulsifying Waterborne Epoxy Curing Agent at Room Temperature

Polyethylene glycol 1000 (PEG1000) and epoxy resin E20 were used to synthesize the E20/PEG1000 polymer (EP1K), which was later transformed into a self-emulsifying water-based epoxy curing agent by reacting with m-Xylylenediamine (MXDA). The effects of molecular weight, the molar ratio of the raw materials, the catalyst dosage, and the different co-solvents on the properties of the prepared curing agent were systematically explored. The infrared absorption spectra of E20, EP1K, and the water-based epoxy curing agent were compared and analyzed. The coating properties of the waterborne epoxy varnish, which was based on water-based epoxy curing agents to emulsify and cure the resin E44, were systematically tested. The results demonstrated that with a molar ratio of 1:1:4 of PEG1000, E20, and MXDA, the boron trifluoride etherate (BF3·Et2O) as catalyst accounts for 0.3% of the total mass of E20 and PEG1000, and an applicable period of 3 h for the prepared varnish, the anti-corrosion performance, and mechanical properties of the coatings were excellent.

Integrating Process Development and Safety Analysis for Scale-Up of a Diborane-Generating Reduction Reaction

Our company has developed a robust and scalable process to synthesize an amino alcohol tosylate salt, a penultimate intermediate in the synthesis of nemtabrutinib. A key reaction in this synthetic sequence is a reductive acetal ring opening using boron trifluoride diethyl etherate as a Lewis acid and triethylsilane as the reducing agent. Detailed mechanistic inquisition revealed that in the presence of sulfolane, boron trifluoride is reduced by triethylsilane to generate diborane as the active reductant. Diborane poses many process safety hazards; it is highly reactive, flammable, and acutely toxic. The reaction headspace was studied using infrared spectroscopy and gas chromatography, while the reaction stream was studied using heat flow and adiabatic calorimetry to ensure safe scale-up of the process. Process understanding demonstrated that containing diborane within the reactor was essential to control key impurities. Extensive development efforts were directed to design a process that could safely sequester the hazardous gas. Herein, we describe the process safety analysis, the optimization, and the scale-up of the reduction reaction and the isolation, producing two batches of the amino alcohol tosylate salt with high purity at a pilot scale.

Carbonyl compounds and inorganic Brønsted acids as catalysts for electropolymerization of conductive polymers

For the electropolymerization of various conductive polymers, boron trifluoride diethyl etherate is commonly used as solvent to grant mild polymerization conditions – although it easily decomposes and leads to film qualities with low reproducibility. By using an appropriate catalyst, films with improved properties can be deposited at lower potentials from stable solvents in a reproducible manner. In this communication, various carbonyl compounds and inorganic Brønsted acids were investigated as catalysts for thiophene and pyrrole electropolymerization in acetonitrile and water. In a series of cyclic voltammetry experiments, catalysts were found to dramatically reduce the initial oxidation potential of the monomers. Hereby, the catalytic effect depended on the electrophilic nature of the catalyst centre, which is majorly influenced by the nature of the ligands. A Raman spectroscopy study demonstrated a decreased aromaticity of the monomers in contact with appropriate catalysts. By exemplarily investigating the catalysing effect of butyric acid on pyrrole polymerization in acetonitrile, conductive films with a lower charge transfer resistance resulted, as well as greater homogeneity and smoothness. Films were characterized by electrochemical impedance spectroscopy, white light interferometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, as well as surface-enhanced Raman spectroscopy. The catalysts presented in this communication convince with low prices and high solubility in acetonitrile and water, are already available in most labs, and can therefore serve as universal tools for the mild electropolymerization of well-known as well as novel monomers for innovative applications.

Synthesis of 2-Alkyl-2-(2-furanyl)-1,3-cyclopentanediones

Abstract2,2-Disubstituted 1,3-cyclopentanediones are versatile building blocks for synthesizing complex natural products with bicyclic structures including cyclopentane rings. The reported method for the synthesis of these compounds involves the semi-pinacol rearrangement of a Mukaiyama aldol adduct prepared from a ketone/ketal and 1,2-bis(trimethylsilyloxy)cyclobutene. However, the adoption of α-oxy-functionalized ketones/ketals is quite difficult, as demonstrated by our experiments. To overcome this limitation of the method, 2-acylfuran derivatives were used as the reactants to synthesize 2,2-disubstituted 1,3-cyclopentanediones. Furthermore, two reaction conditions, that is, the use of 1.4 equivalents of a boron trifluoride-diethyl ether complex or 0.4 and 0.2 equivalent of trimethylsilyl triflate and methoxytrimethylsilane, respectively, were established for the conversion of 2-acylfurans into the corresponding 1,3-cyclopentanediones in acceptable yields. The transformations of the furan rings in the obtained products were also investigated.

An Efficient Combinatorial Synthesis of Novel Thiazolidinone‐Bis Schiff Base Hybrids Using One‐Pot Multicomponent Reaction

AbstractA facile multicomponent synthesis of novel thiazolidinone‐bis Schiff base hybrids has been developed using readily available starting materials. The four‐component reaction of isothiocyanate, hydrazine, aldehyde and α‐bromoester in water readily affords thiazolidinone‐bis Schiff base hybrids, whereas the five‐component strategy involving the same reactants in the presence of boron trifluoride etherate in acetonitrile leads to the formation of the fully functionalized thiazolidinone‐bis Schiff base hybrids.

Boron Trifluoride Etherate Promoted Regioselective 3-Acylation of Indoles with Anhydrides

An efficient, high-yielding and scalable procedure for the regioselective 3-acylation of indoles with anhydrides promoted by boron trifluoride etherate under mild conditions was reported. This novel protocol provided a simple way to prepare 3-(benzofuran-2-yl) indole in three steps.

Bioactivity and Cell Imaging of Antitumor Fluorescent Agents (Curcumin Derivatives) Coated by Two-Way Embedded Cyclodextrin Strategy.

Curcumin has a wide range of pharmacological activities, which can be used to treat tumors, inflammation and other diseases. However, curcumin's poor solubility and low bioavailability limit its application. In this article, the structure of curcumin was modified with boron trifluoride ether to change fluorescent labeling. The compounds were then embedded into the hydrophobic cavity of α-cyclodextrin and hydroxypropyl β-cyclodextrin to form inclusion complexes. The two inclusion complexes have excellent photophysical properties, and the maximum emission wavelength is in the range of 550-565 nm. In addition, the two compounds were applied to the fluorescence imaging of HCT-116 cells and HeLa cells, and the proliferation toxicity of the compounds was detected. Both compounds showed certain inhibitory effects on the proliferation of cancer cells. In short, the fluorescent drug molecule synthesized in this article has great reference value for the development of new dosage forms of curcumin.

Performance Improvement of Lithium Metal Batteries Enabled By LiBF3CN as a New Electrolyte Additive

A newly synthesized electrolyte additive, lithium trifluoro(cyano) borate (LiBF3CN), has been investigated for electrochemical performance improvement of lithium metal batteries. The LiBF3CN has a structure where one fluorine atom of BF4 − is substituted with a cyano group (−CN) prepared by the reaction of boron trifluoride etherate with lithium cyanide. The electrochemical performance in symmetric Li/Li cells and NCM523/Li cells is significantly improved upon the incorporation of LiBF3CN as an electrolyte additive into a carbonate-based electrolyte. Extensive characterization of the deposited lithium metal reveals that a thin (≈20 nm) and robust SEI composed of LiNxOy, Li3N and Li2O is formed by the reductive decomposition of the LiBF3CN additive, which plays an important role in decreasing the resistance and stabilizing lithium deposition/stripping. The insight into the substitution effect of a functional group obtained from this work provides guidance for the design of new electrolyte additives.

Boron Trifluoride Etherate-Controlled Reactions of Methyl Enol Ethers: Selective Synthesis of Dihydrofuro[3,2-c]chromenone and Furo[3,2-c]chromenone Derivatives

AbstractA facile one-step synthetic approach to dihydrofuro-[3,2-c]chromenones and furo[3,2-c]chromenones by the reaction of methyl enol ethers with 4-hydroxycoumarins under metal-free conditions is presented. Dihydrofuro[3,2-c]chromenones and furo[3,2-c]-chromenones were selectively obtained by controlling the stoichiometry of boron trifluoride diethyl etherate. An unexpected aryl-group migration followed by aromatization of the furan moiety, leading to a variety of furo[3,2-c]chromenone derivatives in good yields, is reported.

Cationic Copolymers of Norbornylized Seed Oils for Fiber-Reinforced Composite Applications.

Norbornylized seed oils, i.e., norbornylized linseed oil (NLO), norbornylized soybean oil (NSO), and norbornylized high oleic soybean oil (NHOSO), were synthesized via the Diels–Alder reaction of seed oil and dicyclopentadiene (DCPD) at high temperature (∼235 °C) and high pressure (∼80 psi), followed by cationic copolymerization using DCPD with boron trifluoride diethyl etherate catalyst. Norbornylized seed oils were characterized using H1 nuclear magnetic resonance (NMR), attenuated total reflectance-Fourier transform infrared, and gel permeation chromatography (GPC). Copolymers were formulated with four different DCPD contents, and curing was investigated using dynamic differential scanning calorimetry (DSC) measurements. It was found that the curing followed NLO > NSO > NHOSO with NLO having the highest exotherm, lowest activation energy, and lowest onset temperature. Furthermore, the gelation times were the least for NLO-DCPD copolymers. As anticipated, the degree of unsaturation and norbornene moieties strongly influenced the curing of copolymer thermosets. The copolymer products were compression-molded into thermosets and characterized by DSC, Soxhlet extraction, thermogravimetric analysis (TGA), H1 NMR, solid-state C13 NMR, and GPC. NLO-DCPD thermosets demonstrated high cure, higher thermal stability, glass transition temperature, and cross-linking capability compared to the other seed oil-DCPD counterparts. NMR and GPC results further suggested that bis-allylic and norbornene units concomitantly participated very actively during the cationic curing reaction. Moreover, scanning electron microscopy images of glass fiber-reinforced NLO-DCPD copolymer composites demonstrated good interfacial adhesion between the polymer matrix and fiber phases, imparting enhanced thermo-mechanical properties. This research opens a new venue for higher biobased greener polymer constituent for composite applications.

One‐Pot Transition‐Metal‐Free Synthesis of Polysubstituted Fused Benzene Derivatives from Methyl Enol Ethers and Alkynes

A one-pot synthesis of polysubstituted fused benzene derivatives from methyl enol ethers and alkynes is reported. A wide variety of diversely functionalized naphthalene and phenanthrene derivatives were obtained in good to excellent yields. Due to the fluorescent nature of naphthalene, selected compounds were screened for the solvatochromism study.

Synthesis of a new tripod BODIPY dye bearing N-tert-Butoxycarbonyl amine and its acetylation

A new tripod boron dipyrromethene (BODIPY) dye bearing N-tert-butoxycarbonyl (N-Boc) amine side chain was synthesized and the functionality was confirmed by means of its acetylation reaction with acetic anhydride. Deprotection of the N-Boc protective group had been successfully performed using boron trifluoride etherate (BF3·OEt2) solution alone or the combination of BF3·OEt2 and molecular sieves to solve the susceptibility of the BODIPY fluorophore under the protonic acid conditions. All the new structures had been characterized by NMR, HRMS and IR spectra. A conformational isomeric phenomenon was observed originating from partly restricted rotation of the RNH group attached to the 1,3,5-triazine ring. This work made the chemical transformation via amine functionality around meso position in the tripod BODIPY available.