Tetrabutylammonium Fluoride Research Articles

DESILYLATION OF Β-CYCLODEXTRIN DERIVATIVE MODIFIED WITH PHOSPHOCYCLIC FRAGMENTS

The work discusses the results of an experimental study of the possibility of removing tert-butyldimethylsilyl protection of primary hydroxyl groups from position 6 of the molecule of a β-cyclodextrin derivative modified at the secondary hydroxyl groups of positions 2,3 with phosphocyclic fragments. The resulting cyclodextrin derivative, containing phosphocyclic fragments along the wide rim of the cyclodextrin torus and free hydroxyl groups along the narrow edge, can act as an object of targeted modification of primary hydroxyl groups, as well as as a molecular container with large cavity sizes and rigidity of the cyclodextrin framework for obtaining inclusion compounds with various molecules. It has been shown that the use of a popular desilylation reagent, ammonium fluoride in methanol, leads to the destruction of phosphocyclic fragments, accompanied by the rupture of P-N and P-O bonds, which is confirmed by NMR spectroscopy data on the 31P nucleus. When using another popular reagent - tetrabutylammonium fluoride in a solution of tetrahydrofuran at a temperature of 60 °C for 10 h, desilylation occurs without being accompanied by destruction. In this case, an important condition is the complete absence of water in the desilylation reagent. Even small amounts of residual water lead to hydrolytic destruction of phosphocyclic fragments. When tetrabutylammonium tetrafluoroborate was used as a desilylation reagent in tetrahydrofuran, the effect of phosphocyclic fragments on the desilylation process was noted. Thus, when this reagent acts on β-cyclodextrin silylated at the primary hydroxyl groups at a temperature of 60 °C, partial desilylation is observed, the degree of which reaches approximately 30% in 6 h. When this reagent acts on a silyl derivative containing phosphocyclic fragments, under the same conditions, desilylation does not occur at all. This fact may be associated with supramolecular effects accompanying the desilylation process. For citation: Sutyagin A.A. Desilylation of β-cyclodextrin derivative modified with phosphocyclic fragments. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 33-39. DOI: 10.6060/ivkkt.20246711.7054.

Metal-Free Wet Chemistry for the Fast Gram-Scale Synthesis of γ-Graphyne and its Derivatives.

γ-Graphyne (GY), an emerging carbon allotrope, is envisioned to offer various alluring properties and broad applicability. While significant progress has been made in the synthesis of GY over recent decades, its widespread application hinges on developing efficient, scalable, and accessible synthetic methods for the production of GY and its derivatives. Here we report a facile metal-free nucleophilic crosslinking method using wet chemistry for fast gram-scale production of GY and its derivatives. This synthesis method involves the aromatic nucleophilic substitution reactions between fluoro-(hetero)arenes and alkynyl silanes in the presence of a catalytic amount of tetrabutylammonium fluoride, where the fluoride plays a crucial role in removing protective groups from alkynyl silanes and generating reactive alkynylides. Our comprehensive analysis of the as-prepared GY reveals a layered structure, characterized by the presence of the C(sp)-C(sp2) bond. The synthetic strategy shows remarkable tolerance to various functional groups and enables the preparation of diverse F-/N-rich GY derivatives, using electron-deficient fluoro-substituted (hetero)arenes as precursors. The feasibility of producing GY and derivatives from fluorinated (hetero)arenes through the metal-free, scalable, and cost-effective approach paves the way for broad applications of GY and may inspire the development of new carbon materials.

Naphthoindole-2-carboxamides as a lipophilic chemotype of hetarene-anthraquinones potent against P-gp resistant tumor cells

The acquisition of multidrug resistance (MDR) to chemotherapy is a major obstacle to successful cancer treatment. Aiming to improve the potency of anthraquinone-derived antitumor compounds against MDR cancer cells, we employed a rational design approach to develop new heteroarene-fused anthraquinones. Shifting the carboxamide group in the naphtho[2,3-f]indole scaffold from the 3-position to 2 increased the lipophilicity and P-glycoprotein (P-gp) binding of the derivatives, potentially enhancing their ability to circumvent P-gp-mediated MDR. To validate the computations, we developed a scheme for heterocyclization into esters of naphtho[2,3-f]indole-2-carboxylic acid, based on the 5-endo-dig cyclization of 2-alkynyl-3-amino-1,4-dimethoxyanthraquinone under mild basic conditions using tetra-n-butylammonium fluoride (TBAF). The synthesized naphthoindole-2-carboxamides, particularly compound 1a bearing (S)-3-aminopyrrolidine in the carboxamide fragment, demonstrated the highest antiproliferative activity. Most importantly, 1a suppressed the growth of the P-gp-positive K562/4 leukemia tumor cell line (resistance index = 2.4), while its 3-isomer LCTA-2640 and Dox did not (RI = 125 and 140, respectively). Studies of intracellular uptake and distribution showed that 1a, unlike its 3-substituted isomer, effectively accumulated in resistant tumor cells, confirming the correlation between in silico and experimental data. The lead compound 1a interacts with DNA duplex and inhibits topoisomerase 1 but does not induce oxidative stress. Treatment with 1a increases the population of apoptotic cells in both K562 and K562/4 sublines, regardless of the cell cycle phase. Taken together, this work provides an interesting example of how a little modification in chemical structure can lead to striking differences in antitumor properties. In conclusion, we have identified a potent class of compounds that offer distinct advantages in combating resistant tumor cells.

Novel sulfonylurea fluorescence probes for antiproliferative activity, detection and imaging of fluoride ions in living cells

In this study, four novel triphenylpyrazoline 4-toluenesulfonylureas (PYSUs) were synthesized to develop potential anticancer drugs and fluorescent probes for the detection of F− ions. The compounds were synthesized via a two-step microwave-assisted method. The antiproliferative activity of the PYSUs was tested against two cancer cell lines: HepG2 and MDA-MB-231. Among the compounds, 3a exhibited strong activity against both cell lines, while 3b showed strong activity against MDA-MB-231 cells but weaker inhibition of HepG2 cells. Furthermore, compound 3b was identified as the best fluorescent probe, with an increase in emission intensity in the presence of F− ions from tetrabutylammonium fluoride (TBAF). In DMSO, the emission wavelength was found to be 518 nm (green) with an excitation wavelength of 469 nm. The limit of detection (LOD) was calculated to be 0.269 mM in the linear range of 5–10 mM. The interaction mechanism between F− ions and compound 3b was further explored via DFT/TDDFT calculations. Additionally, fluorescent imaging of TBAF-incubated MDA-MB-231 and HepG2 cells confirmed the potential of PYSUs as fluorescent sensors for F− ions in living cancer cells.

Zirconium Hydride Catalysis Initiated by Tetrabutylammonium Fluoride.

In our drug discovery campaigns to target the oncogenic drivers of cancers, the demand for a chemoselective, stereoselective and economical synthesis of chiral benzylamines drove the development of a catalytic zirconium hydride reduction. This methodology uses the inexpensive, bench stable zirconocene dichloride, and a novel tetrabutylammonium fluoride activation tactic to catalytically generate a metal hydride under ambient conditions. The diastereo- and chemoselectivity of this reaction was tested with the preparation of key intermediates from our discovery programs and in the scope of sulfinyl ketimines and carbonyls relevant to medicinal chemistry and natural product synthesis. A preliminary mechanistic investigation conducted into the role of tetrabutylammonium fluoride indicates that formation of a zirconocene fluoride occurs to initiate catalysis. The implications of this convenient activation approach may provide expanded roles for zirconium hydrides in catalytic transformations.

Development of a new type of highly effective etchant solution for glue residue in wafer-level packaging process

We synthesize an etchant solution designed to remove polydimethylsiloxane (PDMS) residues from semiconductor wafers during wafer-to-wafer processing in advanced semiconductor packaging (AVP). The etchant solution is produced by combining hexane, a nonpolar swelling solvent, with tetrabutylammonium fluoride (TBAF), a fluorine-based compound, to enhance PDMS etching. We evaluate the etching rate of PDMS using various solvent mixtures, including 1-vinyl-2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, and 1-octyl-2-pyrrolidone (NOP), with different concentrations of TBAF (1.0–5.0 wt%). Notably, NOP, which contains octyl groups, demonstrates the highest PDMS etching rate, particularly when combined with 70.0 wt% hexane. The optimized solution, F3-NOP/H70, achieves an etching rate of 85.7 μm/min. Further testing confirms that the F3-NOP/H70 solution effectively removes PDMS residues from wafer surfaces without damaging dielectric layers, such as the photosolder resist and photosensitive polyimide. These results indicate that the F3-NOP/H70 solution efficiently dissolves and removes PDMS residues and preserves the integrity of adjacent wafer components, making it a promising candidate for AVP applications. This study emphasizes the importance of selecting appropriate solvent systems for residue removal in semiconductor manufacturing and offers a practical solution to enhance device quality and reliability. This approach can potentially be applied at various stages of semiconductor processing, where residue management is essential.

Rapid and ultra-sensitive trace water determination in organic solvents utilizing nitrobenzoxadiazole (NBD)-based fluorescent sensing system

The presence of minute quantities of water in organic solvents can affect the progress of many reactions and cause unnecessary losses and even safety accidents in the chemical industry, especially in the productions process of organic fine chemicals. Therefore, it is necessary to carry out high-performance strategies for trace water detections in commonly used organic solvents. In this work, a fluorescent sensing system based on competitive binding of protons has been developed, demonstrating remarkable responses by UV–vis absorption and fluorescence two-modes toward a trace amount of water in organic solvents including 1,4-dioxane (Diox), tetrahydrofuran (THF), acetonitrile (MeCN), acetone (ACE), dimethylsulfoxide (DMSO) and mixed organic solvents (THF: MeCN=1: 1). The key component of the sensing system is a newly designed fluorophore NBD-PMA, which can be deprotonated to form a dynamic non-luminescent adduct, namely NBD-PMA-F, by an organic fluoride salt tetrabutylammonium fluoride (TBAF). NBD-PMA-F can be reprotonated via using trace water, exhibiting fluorescence turn on of the system. The as-prepared sensing system shows superior sensitivity, low detection limits (v/v, 0.0007 %), quick response speed (≤1.2 s) and good reversibility. Moreover, naked-eye visual rapid detection has also been successfully realized at ambient temperature, which demonstrated their practical applications value for trace water determinations.

Anion-complex formation for the wettability control of a boron-containing π-conjugated polymer

An anion-responsive boron-containing π-conjugated polymer was synthesized via the Sonogashira coupling polymerization. The 11B NMR, UV/vis absorption, and fluorescence spectra confirmed the formation of an anion complex between the polymer and tetrabutylammonium fluoride (TBAF). Thin films were then prepared either by the pre-addition method, where the thin film was prepared using a solution of the polymer and TBAF, or by the post-addition method, where the polymer thin film was treated with an aqueous TBAF solution. The contact angle measurements revealed an enhancement in wettability with both methods. Consequently, wettability can be controlled via anion-complex formation at the surface.

Barbituric acid‐derived azo dye metal complexes: Synthesis, characterization, DFT, and antimicrobial analysis

Two novel metal complexes, C1 and C2, were synthesized through the reaction of an azo dye ligand, obtained by coupling 4‐chloroaniline with 1,3‐dimethyl barbituric acid. The structure of the ligand was confirmed using Fourier‐transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance (NMR). UV–Vis spectroscopy was employed to assess the ligand's sensing ability toward six different metal ions. Comprehensive characterization of the synthesized metal complexes was conducted using elemental analysis, X‐ray photoelectron spectroscopy (XPS), thermogravimetric analysis–difference thermogravimetry (TGA‐DTG), FTIR, UV–Vis spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and single‐crystal X‐ray diffraction (SC‐XRD). X‐ray analysis revealed octahedral coordination geometry with a 2:1 ligand‐to‐metal ratio and dimethylformamide (DMF) coordination with the metal atom in both complexes. Hirshfeld analysis and 2D fingerprint plots were employed to investigate supramolecular and intermolecular interactions within the crystal system. Density functional theory (DFT/B3LYP) calculations were utilized to compute energy gaps and other important theoretical features. Sensing experiments with tetrabutylammonium fluoride (TBAF) were conducted at a concentration of 1 × 10−5 M. Furthermore, the bioactivity of the synthesized metal complexes and ligand L was evaluated through molecular docking studies against Protein Data Bank (PDB IDs) 4XUY (Staphylococcus aureus) and 3BQW (Aspergillus niger). Also, antimicrobial activity was assessed using the agar well diffusion technique, revealing that complexes C1 and C2 exhibited enhanced antimicrobial activities against the tested organisms compared to the parent azo dye ligand. The computational and experimental bioactivity data are in good agreement with each other.

Deprotection of N1-methyladenosine-containing RNA using triethylamine hydrogen fluoride

The N 1-methyladenosine (m1A) epigenetic modification exists in many RNAs and is related to many human diseases. Chemically synthesized RNAs containing the modification are required for projects aimed at studying biological processes, mechanisms, and pathogenesis related to m1A. Existing methods for the synthesis of m1A containing RNAs use tetrabutylammonium fluoride (TBAF) for the deprotection of the 2'-silyl protecting groups. Since TBAF is nonvolatile, and is relatively non-polar, its use in the desilylation of RNA requires repeated desalting, which is tedious and gives low yields. Here we report the use of the volatile and neat triethylamine hydrogen fluoride (TEA-HF) for desilylation of m1A RNA synthesis. We found that the method is much simpler, and—in our hands—give significantly higher yield of RNA. Two major concerns for m1A RNA synthesis are depurination and Dimroth rearrangement. HPLC and MALDI MS of the RNA indicated that depurination is not a problem for the new method. The absence of Dimroth rearrangement is proven by RNA digestion followed by HPLC analysis of the nucleosides.

Conjugated Polymers with Self-Immolative Sidechain Linkers for Carbon Nanotube Dispersion.

Single-walled carbon nanotubes (SWNTs) are promising materials for generating high-performance electronic devices. However, these applications are greatly restricted by their lack of purity and solubility. Commercially available SWNTs are a mixture of semi-conducting (sc-) and metallic (m-) SWNTs and are insoluble in common solvents. Conjugated polymers can selectively disperse either sc- or m-SWNTs and increase their solubility; however, the conductivity of conjugated polymer-wrapped SWNTs is largely affected by the polymer side chains. Here, a poly(fluorene-co-phenylene) polymer that contains a self-immolative linker as part of its sidechains is reported. The self-immolative linker is stabilized with a tert-butyldimethylsilyl ether group that, upon treatment with tetra-n-butylammonium fluoride (TBAF), undergoes a 1,6-elimination reaction to release the sidechain. Sonication of this polymer with SWNTs in tetrahydrofuran (THF) results in concentrated dispersions that are used to prepare polymer-SWNT thin films. Treatment with TBAF caused side-chain cleavage into carbon dioxide and the corresponding diol, which can be easily removed by washing with solvent. This process is characterized by a combination of absorption and Raman spectroscopy, as well as four-point probe measurements. The conductance of the SWNT thin films increased ≈60-fold upon simple TBAF treatment, opening new possibilities for producing high-conductivity SWNT materials for numerous applications.

Selective CO2 Capture from CO2/N2 Gas Mixtures Utilizing Tetrabutylammonium Fluoride Hydrates.

Gas hydrates, a type of inclusion compound capable of trapping gas molecules within a lattice structure composed of water molecules, are gaining attention as an environmentally benign gas storage or separation platform. In general, the formation of gas hydrates from water requires high-pressure and low-temperature conditions, resulting in significant energy consumption. In this study, tetrabutylammonium fluoride (TBAF) was utilized as a thermodynamic promoter forming a semi-clathrate-type hydrate, enabling gas capture or separation at room temperature. Those TBAF hydrate systems were explored to check their capability of CO2 separation from flue gas, the mixture of CO2 and N2 gases. The formation rates and gas storage capacities of TBAF hydrates were systematically investigated under various concentrations of CO2, and they presented selective CO2 capture behavior during the hydrate formation process. The maximum gas storage capacities were achieved at 2.36 and 2.38 mmol/mol for TBAF·29.7 H2O and TBAF·32.8 H2O hydrate, respectively, after the complete enclathration of the feed gas of CO2 (80%) + N2 (20%). This study provides sufficient data to support the feasibility of TBAF hydrate systems to be applied to CO2 separation from CO2/N2 gas mixtures based on their CO2 selectivity.

Tetra-n-Butyl Ammonium Fluoride (TBAF) as an Efficient Catalyst

Abstract: Tetra-n-butylammonium fluoride (TBAF) is an organic compound with the formula C16H36FN. It can exist as anhydrous or hydrated (C16H42FNO3). It is soluble in water and THF and utilized as a base in the preparation of triple monoamine reuptake inhibitors, conjugated dienoic acid esters, and polyacetylenic glucosides. This review aims to summarize the chemistry of TBAF.

Ultralong Cycling and Safe Lithium-Sulfur Pouch Cells for Sustainable Energy Storage.

While layered metal oxides remain the dominant cathode materials for the state-of-the-art lithium-ion batteries, conversion-type cathodes such as sulfur present unique opportunities in developing cheaper, safer, and more energy-dense next-generation battery technologies. There has been remarkable progress in advancing the laboratory scale lithium-sulfur (Li-S) coin cells to a high level of performance. However, the relevant strategies cannot be readily translated to practical cell formats such as pouch cells and even battery pack. Here these key technical challenges are addressed by molecular engineering of the Li metal for hydrophobicization, fluorination and thus favorable anode chemistry. The introduced tris(2,4-di-tert-butylphenyl) phosphite (TBP) and tetrabutylammonium fluoride (TBA+F-) as well as cellulose membrane by rolling enables the formation of a functional thin layer that eliminates the vulnerability of Li metal towards the already demanding environment required (1.55% relative humidity) for cell production and gives rise to LiF-rich solid electrolyte interphase (SEI) to suppress dendrite growth. As a result, Li-S pouch cells assembled at a pilot production line survive 400 full charge/discharge cycles with an average Coulombic efficiency of 99.55% and impressive rate performance of 1.5 C. A cell-level energy density of 417Wh kg-1 and power density of 2766W kg-1 are also delivered via multilayer Li-S pouch cell. The Li-S battery pack can even power an unmanned aerial vehicle of 3kg for a fairly long flight time. This work represents a big step forward acceleration in Li-S battery marketization for future energy storage featuring improved safety, sustainability, higher energy density as well as reduced cost.

Transition‐Metal‐Free Approach for Z‐Vinyl Fluorides by Hydrofluorination of Alkynes bearing SF4 and SF5 Groups

AbstractThe synthesis of vinyl fluorides plays a crucial role in various scientific disciplines, including pharmaceutical and materials sciences. Herein, we present a direct and stereoselective hydrofluorination method for the synthesis of Z isomers of vinyl fluorides from alkynes containing unexplored SF5 and SF4 groups. Our strategy employed tetrabutylammonium fluoride (TBAF) as a fluorine source. It demonstrates high compatibility with aryls, biaryls, heteroaryls, and tert‐alkyl groups, allowing facile incorporation of SF5 and SF4 groups across the triple bond without any transition‐metal catalysts. This approach avoids the potential decomposition of the SF5 or SF4 units via coordination with transition metals or acidic protic sources. Remarkably, this transformation proceeded at room temperature without any additional additives, providing the Z isomer of vinyl fluorides in excellent yield and high selectivity. The presence of a water molecule as a hydrate in TBAF is essential for efficient conversion. This methodology opens new avenues for the synthesis of enchanting SF5‐ and SF4‐containing fluorinated vinylic scaffolds, thereby providing advanced opportunities for novel drug discovery and fluorinated polymers.

Transition-Metal-Free Approach for Z-Vinyl Fluorides by Hydrofluorination of Alkynes bearing SF4 and SF5 Groups.

The synthesis of vinyl fluorides plays a crucial role in various scientific disciplines, including pharmaceutical and materials sciences. Herein, we present a direct and stereoselective hydrofluorination method for the synthesis of Z isomers of vinyl fluorides from alkynes containing unexplored SF5 and SF4 groups. Our strategy employed tetrabutylammonium fluoride (TBAF) as a fluorine source. It demonstrates high compatibility with aryls, biaryls, heteroaryls, and tert-alkyl groups, allowing facile incorporation of SF5 and SF4 groups across the triple bond without any transition-metal catalysts. This approach avoids the potential decomposition of the SF5 or SF4 units via coordination with transition metals or acidic protic sources. Remarkably, this transformation proceeded at room temperature without any additional additives, providing the Z isomer of vinyl fluorides in excellent yield and high selectivity. The presence of a water molecule as a hydrate in TBAF is essential for efficient conversion. This methodology opens new avenues for the synthesis of enchanting SF5 - and SF4 -containing fluorinated vinylic scaffolds, thereby providing advanced opportunities for novel drug discovery and fluorinated polymers.

Experimental and Theoretical Studies on Stereomutation Through gem‐Difluorocyclopropanylide Intermediates

AbstractA desilylation process of optically active silyl‐substituted gem‐difluorocyclopropanes with tetrabutylammonium fluoride (TBAF) showed a substantial reduction of enantiopurity of the resultant gem‐difluorocyclopropanes even at ambient temperatures. The electron‐withdrawing aryl substituent at the 3‐position in the 1‐silyl‐2,2‐difluorocyclopropane system accelerated the racemization, indicating a correlation with the stability of the anionic intermediates. The plausible racemization pathway through homolytic cleavage of the distal bond in gem‐difluorocyclopropane is inconsistent with the experimental results because the high energy of >34 kcal/mol is required for generating the open‐shell 2,2‐difluoropropane‐1,3‐diyl skeleton. The DFT studies using the anionic 2,2‐difluoromethyl‐3‐phenylcyclopropanylide intermediate supported the alternative isomerization pathway through the intramolecular migration of hydrogen and the resultant thermodynamically stable 2,2‐difluoromethyl‐1‐phenylcyclopropanylide anion could facilitate the racemization process at the stereocenter. Although the transition state indicated considerable activation energies, the high frequency of imaginary vibration should correlate with a barrier of a very narrow width enabling quantum tunneling under the H‐migration step. The observed isotope effect is compatible with the proposed mechanism through the intramolecular H‐migration.

A strong nucleophilic fluorination agent to achieve highly stable in-situ 3D cross-linked gel polymer electrolyte for lithium-ion batteries

The Gel Polymer Electrolyte (GPE) is recognized as a promising alternative to conventional electrolytes, aiming to enhance the longevity and energy density of lithium-ion batteries (LIBs). However, several challenges persist, particularly concerning the conductivity and voltage window of GPE in battery systems. In this study, we introduce an in-situ 3D crosslinked GPE, using polymethyl methacrylate (PMMA) as the monomer and polyethylene glycol dimethacrylate (PEGDMA) as the crosslinking agent, to ensure structural stability and optimized ion conductivity. We also incorporate a potent nucleophilic fluorination agent, Tetrabutylammonium fluoride (TBAF), to augment the compatibility and oxidation resistance of the formulated FGPPE. The recurring (–CH2CH2O-) units of PEGDMA, coupled with in-situ lithium fluoride (LiF) and C-F groups introduced by TBAF, endow the FGPPE with a remarkable ionic conductivity of 7.8 mS cm−1 and a distinctly electrochemical stability of 4.65 V. Notably, the Li metal anode, featuring an F-rich solid-state interface (SEI), demonstrates uniform Li+ deposition, sustaining a cycling life of 1000 h and maintaining a commendable average coulomb efficiency of 98.5 % over 300 cycles. Additionally, the NCM811/SiC pouch cell integrated with FGPPE showcases superior cycling stability, retaining 99.4 % of its capacity after 600 cycles at an elevated voltage of 4.45 V. Such advancements in gel polymer electrolyte design can significantly expedite the commercial deployment of gel polymer Li-ion batteries.

Speciation and kinetics of fluoride transfer from tetra-n-butylammonium difluorotriphenylsilicate ('TBAT').

Tetra-n-butylammonium difluorotriphenylsilicate (TBAT) is a conveniently handled anhydrous fluoride source, commonly used as a surrogate for tetra-n-butylammonium fluoride (TBAF). While prior studies indicate that TBAT reacts rapidly with fluoride acceptors, little is known about the mechanism(s) of fluoride transfer. We report on the interrogation of the kinetics of three processes in which fluoride is transferred from TBAT, in THF and in MeCN, using a variety of NMR methods, including chemical exchange saturation transfer, magnetisation transfer, diffusion analysis, and 1D NOESY. These studies reveal ion-pairing between the tetra-n-butylammonium and difluorotriphenylsilicate moieties, and a very low but detectable degree of fluoride dissociation, which then undergoes further equilibria and/or induces decomposition, depending on the conditions. Degenerate exchange between TBAT and fluorotriphenylsilane (FTPS) is very rapid in THF, inherently increases in rate over time, and is profoundly sensitive to the presence of water. Addition of 2,6-di-tert-butylpyridine and 3 Å molecular sieves stabilises the exchange rate, and both dissociative and direct fluoride transfer are shown to proceed in parallel under these conditions. Degenerate exchange between TBAT and 2-naphthalenyl fluorosulfate (ARSF) is not detected at the NMR timescale in THF, and is slow in MeCN. For the latter, the exchange is near-fully inhibited by exogenous FTPS, indicating a predominantly dissociative character to this exchange process. Fluorination of benzyl bromide (BzBr) with TBAT in MeCN-d3 exhibits moderate progressive autoinhibition, and the initial rate of the reaction is supressed by the presence of exogenous FTPS. Overall, TBAT can act as a genuine surrogate for TBAF, as well as a reservoir for rapidly-reversible release of traces of it, with the relative contribution of the pathways depending, inter alia, on the identity of the fluoride acceptor, the solvent, and the concentration of endogenous or exogenous FTPS.

Experimental Study of the Rate of Methane Hydrate Formation: Influence of Simultaneous Utilization of Tetra n-Butylammonium Fluoride and Sodium Dodecyl Sulfate

Experimental Study of the Rate of Methane Hydrate Formation: Influence of Simultaneous Utilization of Tetra n-Butylammonium Fluoride and Sodium Dodecyl Sulfate