Formyl Fluoride Research Articles

Adsorption behavior of HFCO and COF2 gasses on pristine, Al-doped, and N-doped (8, 0) single-wall carbon nanotubes and pristine aluminum nitride nanotube: A first-principles study

The detection of organic pollutants in the environment is crucial due to their significant impact on human health. Formyl fluoride (HFCO) and carbonyl fluoride (COF2) are toxic gasses that contribute to stratospheric ozone depletion. To explore a potential sensor material for these compounds, the adsorption properties of HFCO and COF2 on pristine (8, 0) single-walled carbon nanotubes (SWCNTs), aluminum-doped SWCNTs (Al-SWCNTs), nitrogen-doped SWCNTs (N-SWCNTs), and aluminum nitride nanotube (AlNNTs) were investigated using density functional theory (DFT) calculations. Obtained structural and electronic results reveal no significant after HFCO and COF2 adsorption on pristine SWCNT. However, the conductivity and polarizability of Al- SWCNT increases throw HFCO and COF2 adsorption. It was shown that this adsorption strongly depends on molecular orientation toward SWCNT. Structural and electronic findings show that studied molecules undergoes a physical adsorption to N- SWCNT. However, AlNNT was also found to show significant changes in structural and electronic properties after HFCO and COF2 adsorption. This adsorption leads to a significant (nearly 45%) reduction in the HOMO-LUMO gap of AlNNTs. Therefore, it is proposed from this study that Al-SWCNTs and AlNNTs are promising candidates for HFCO and COF2 gas sensors. Moreover, AlNNTs exhibit intrinsic detection capabilities without structural manipulation via doping which makes AlNNTs particularly attractive for sensor applications. Moreover, the capability of AlNNT without manipulating makes this nanotube a good and easy made candidate for these compounds adsorption.

Pressurized metered-dose inhalers using next-generation propellant HFO-1234ze(E) deposit negligible amounts of trifluoracetic acid in the environment

Pressurized metered-dose inhalers (pMDIs) deliver life-saving medications to patients with respiratory conditions and are the most used inhaler delivery device globally. pMDIs utilize a hydrofluoroalkane (HFA), also known as an F-gas, as a propellant to facilitate the delivery of medication into the lungs. Although HFAs have minimal impact on ozone depletion, their global warming potential (GWP) is more than 1,000 times higher than CO2, bringing them in scope of the F-Gas Regulation in the European Union (EU). The pharmaceutical industry is developing solutions, including a near-zero GWP “next-generation propellant,” HFO-1234ze(E). At the same time, the EU is also evaluating a restriction on per-and polyfluoroalkyl substances (PFAS) under the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation. Trifluoroacetic acid (TFA) is a persistent PFAS and a potential degradation product of HFO-1234ze(E). We quantified yield of TFA from HFO-1234ze(E) using a computational model under Europe-relevant atmospheric conditions. The modeling suggests that most HFO-1234ze(E) degrades into formyl fluoride within 20 days (≥85%) even at the highest examined altitude. These results suggest that TFA yield from HFO-1234ze(E) varies between 0%–4% under different atmospheric conditions. In 2022, France represented the highest numbers of pMDI units sold within the EU, assuming these pMDIs had HFO-1234ze(E) as propellant, we estimate an annual rainwater TFA deposition of ∼0.025 μg/L. These results demonstrate negligible formation of TFA as a degradation product of HFO-1234ze(E), further supporting its suitability as a non-persistent, non-bioaccumulative, and non-toxic future propellant for pMDI devices to safeguard access for patients to these essential medicines.

Reactions with Criegee intermediates are the dominant gas-phase sink for formyl fluoride in the atmosphere

Atmospheric oxidation processes are of central importance in atmospheric climate models. It is often considered that volatile organic molecules are mainly removed by hydroxyl radical; however, the kinetics of some reactions of hydroxyl radical with volatile organic molecules are slow. Here we report rate constants for rapid reactions of formyl fluoride with Criegee intermediates. These rate constants are calculated by dual-level multistructural canonical variational transition state theory with small-curvature tunneling (DL-MS-CVT/SCT). The treatment contains beyond-CCSD(T) electronic structure calculations for transition state theory, and it employs validated density functional input for multistructural canonical variational transition state theory with small-curvature tunneling and for variable-reaction-coordinate variational transition state theory. We find that the M11-L density functional has higher accuracy than CCSD(T)/CBS for the HC(O)F + CH2OO and HC(O)F + anti-CH3CHOO reactions. We find significant negative temperature dependence in the ratios of the rate constants for HC(O)F + CH2OO/anti-CH3CHOO to the rate constant for HC(O)F + OH. We also find that different Criegee intermediates have different rate-determining-steps in their reactions with formyl fluoride, and we find that the dominant gas-phase removal mechanism for HC(O)F in the atmosphere is the reaction with CH2OO and/or anti-CH3CHOO Criegee intermediates.

Novel Carbene Hydroxymethylene Derivatives: Gibbs free energy, NBO, AIM, and Hammett approaches via DFT and MP2 methods

Density functional theory (DFT) and the Møller-Plesset expansion (MP2) calculations were benchmarked to characterize the structure of novel derivatives of carbene hydroxymethylene. In this regard, eleven numbers of primary aldehydes including formaldehyde, acetaldehyde, formyl chloride, 2-chloroacetaldehyde, formyl fluoride, 2-fluoroacetaldehyde, formic acid, propionaldehyde, glyoxal, methyl formate, and formyl bromide (1H-11Br) were scrutinized, at the B3LYP/6-311++G(3d,3p) level of theory. Thereafter, the process of keto-enol tautomerism via a [1,2]-H-shift of 1H-11Br was monitored to reach their corresponding enol forms (1P-11P). For all species (except for one structure), the TS involves a triangle structure of C-O-H and yields cis or trans isomers of a singlet ground-state (S) carbene that contrasts the multiplicity of ordinary carbenes. The bond dissociation energy (BDE) calculations were carried out for the homolytic cleavage of C−H bonds of 1H-11Br. The AIM, as a promising analysis that definitely reveals the nature of the bond, was conducted to characterize the eigenvalues at the bond critical points (BCPs). In addition, the relation between the Hammett equation and thermodynamic parameters was obtained. Our investigation suggests new stable S derivatives of carbene hydroxymethylene that can be isolated.

A general implementation of time-dependent vibrational coupled-cluster theory.

The first general excitation level implementation of the time-dependent vibrational coupled cluster (TDVCC) method introduced in a recent publication [J. Chem. Phys. 151, 154116 (2019)] is presented. The general framework developed for time-independent vibrational coupled cluster (VCC) calculations has been extended to the time-dependent context. This results in an efficient implementation of TDVCC with general coupling levels in the cluster operator and Hamiltonian. Thus, the convergence of the TDVCC[k] hierarchy toward the complete-space limit can be studied for any sum-of-product Hamiltonian. Furthermore, a scheme for including selected higher-order excitations for a subset of modes is introduced and studied numerically. Three different definitions of the TDVCC autocorrelation function (ACF) are introduced and analyzed in both theory and numerical experiments. Example calculations are presented for an array of systems including imidazole, formyl fluoride, formaldehyde, and a reduced-dimensionality bithiophene model. The results show that the TDVCC[k] hierarchy converges systematically toward the full-TDVCC limit and that the implementation allows accurate quantum-dynamics simulations of large systems to be performed. Specifically, the intramolecular vibrational-energy redistribution of the 21-dimensional imidazole molecule is studied in terms of the decay of the ACF. Furthermore, the importance of product separability in the definition of the ACF is highlighted when studying non-interacting subsystems.

Theoretical investigation of electron impact on formyl fluoride (HFCO)

In this paper, a descriptive and detailed theoretical analysis is carried out on electron scattering of formyl fluoride (HFCO) covering a wide impact energy range of 0.1 eV–5000 eV. Due to such a wide impact energy range, we were able to calculate the variety of interaction processes such as eigen phase study to infer about the resonances, vertical electron excitations, differential cross-sections, momentum transfer cross-sections, ionization cross-sections and total scattering cross-sections for electron impact on formyl fluoride. To compute these cross-sections for this energy range, we have used an amalgamation of two theoretical methodologies namely R-matrix via. Quantemol-N, valid for the low energy calculations from 0.1 eV to 20 eV and the Spherical Complex Optical Potential (SCOP) applicable from ionization threshold of the target to 5000 eV. There is a smooth cross over of total cross-sections observed between these two methods at the incident energy just below 20 eV. The present study becomes more important as it presents the electron impact cross-sections on HFCO for the first time and thus provides a reference data set for HFCO over an extensive impact energy range. The data set is important as Hydrofluorocarbons (HFCs) are one class of potential chlorofluorocarbons (CFC) substituents which mainly reacts with the OH radical in the atmosphere leading to the formation of the dominant intermediate product HFCO.

MR-MCTDH[n]: Flexible Configuration Spaces and Nonadiabatic Dynamics within the MCTDH[n] Framework.

Solving the time-dependent Schrödinger equation (TDSE) for large molecular systems is a complicated task due to the inherent exponential scaling of the problem. One of the most successful and versatile methods for obtaining numerically converged solutions for small to medium-sized systems is multiconfiguration time-dependent Hartree (MCTDH). In a recent publication [J. Chem. Phys. 2020, 152, 084101] we introduced a hierarchy of approximations to the MCTDH method which mitigate the exponential scaling by truncating the configuration space based on a maximum excitation level w.r.t. a selected reference configuration. The MCTDH[n] methods are able to treat large systems, but the single-reference Ansatz is not optimal in cases where one (or a few) degrees of freedom are special. Examples could be double-well systems, intramolecular vibrational-energy redistribution (IVR) calculations, or nonadiabatic dynamics. In this work we introduce a multireference (MR) extension to the MCTDH[n] methods where selected higher-order excitations for the special degrees of freedom can be introduced in a simple but flexible way. The resulting MR-MCTDH[n] methods allow for, for example, treating nonadiabatic dynamics within the single-set formalism with the wave packets on each electronic surface described using the same level of approximation. Example calculations are performed on formyl fluoride (IVR), salicylaldimine (double well), and pyrazine (nonadiabatic dynamics). The results show that fast convergence is achieved by extending the configuration space in the special modes that govern the quantum dynamics.

Pd-catalyzed fluoro-carbonylation of aryl, vinyl, and heteroaryl iodides using 2-(difluoromethoxy)-5-nitropyridine

Acyl fluorides have recently gained a lot of attention as robust and versatile synthetic tools in synthetic chemistry. While several synthetic routes to acyl fluorides have been reported, a procedure involving direct insertion of the “fluoro-carbonyl” moiety using a single reagent has not yet been realized. Here we report the preparation of acyl fluorides by palladium-catalyzed fluoro-carbonylation of aryl, vinyl, and heteroaryl iodides using 2-(difluoromethoxy)-5-nitropyridine under CO-free conditions. 2-(difluoromethoxy)-5-nitropyridine is a stable, colorless solid that can be used as an alternative to the toxic gaseous formyl fluoride, which is commonly used under fluoride catalysis conditions. A wide variety of acyl fluorides are efficiently and safely obtained in high yield (up to 99%). A broad range of functional groups is tolerated under the optimized reaction conditions and the method can be applied to the late-stage fluoro-carbonylation of structurally complex Csp2-iodides, including bioactive derivatives, such as Fenofibrate, Isoxepac, and Tocopherol. Furthermore, the one-pot transformation of aryl-iodides, including drug-like molecules, into the corresponding amides by successive fluoro-carbonylation/amidation reactions, demonstrates the potential synthetic utility of this strategy.

Systematic and variational truncation of the configuration space in the multiconfiguration time-dependent Hartree method: The MCTDH[n] hierarchy.

The multiconfiguration time-dependent Hartree (MCTDH) method is a powerful method for solving the time-dependent Schrödinger equation in quantum molecular dynamics. It is, however, hampered by the so-called curse of dimensionality which results in exponential scaling with respect to the number of degrees of freedom in the system and, thus, limits its applicability to small- and medium-sized molecules. To avoid this scaling, we derive equations of motion for a series of truncated MCTDH methods using a many-mode second-quantization formulation where the configuration space is restricted based on mode-combination levels as also done in the vibrational configuration interaction and vibrational coupled cluster methods for solving the time-independent Schrödinger equation. The full MCTDH wave function is invariant with respect to the choice of constraint (or gauge) operators, but restricting the configuration space removes this invariance. We, thus, analyze the remaining redundancies and derive equations for variationally optimizing the non-redundant matrix elements of the constraint operators. As an alternative, we also present a constraint that keeps the density matrices block diagonal during the propagation and the two choices are compared. Example calculations are performed on formyl fluoride and a series of high-dimensional Henon-Heiles potentials. The results show that the MCTDH[n] methods can be applied to large systems and that an optimal choice of constraint operators is key to obtaining the correct physical behavior of the wave function.

Electron impact scattering study on formyl fluoride (HFCO)

SynopsisElectron impact scattering studies with organic compounds play a significant role in studies related to astrophysics and radiation physics. We present here electron impact scattering studies on formyl fluoride as no cross-sectional data is available to the best of our knowledge. Total scattering cross sections (TCS) on comparing with iso-electronic molecule reveals that at low energy molecular dipole moment plays a significant role in cross-section deviation and at high energy the tendency seems to be same in all the formyl series.

Hydrolysis of Formyl Fluoride Catalyzed by Sulfuric Acid and Formic Acid in the Atmosphere.

Formyl fluoride (HFCO) is an important atmospheric molecule, and its reaction with the OH radical is an important pathway when degradation of HFCO is considered in earth’s troposphere. Here, we study the hydrolysis of formyl fluoride (HFCO + H2O) with sulfuric acid (H2SO4) and formic acid (HCOOH) acting as catalysts by utilizing M06-2X, CCSD(T)-F12a, and conventional transitional state theory with Eckart tunneling to explore the atmospheric impact of the above-said hydrolysis reactions. Our calculated results show that H2SO4 has a remarkably catalytic role in the gas-phase hydrolysis of HFCO, as the energy barriers of the HFCO + H2O reaction are reduced from 39.22 and 41.19 to 0.26 and −0.63 kcal/mol with respect to the separate reactants, respectively. In addition, we also find that H2SO4 can significantly accelerate the decomposition of FCH(OH)2 into hydrogen fluoride (HF) and HCOOH. This is because while the barrier height for the unimolecular decomposition of FCH(OH)2 into HF and HCOOH is 31.63 kcal/mol, the barrier height for the FCH(OH)2 + H2SO4 reaction is predicted to be −5.99 kcal/mol with respect to separate reactants. Nevertheless, the comparative relative rate analysis shows that the reaction between HFCO and the OH radical is still the most dominant pathway when the tropospheric degradation of HFCO is taken into account and that the gas-phase hydrolysis of HFCO may only occur with the help of H2SO4 when the atmospheric concentration of OH is about 101 molecules cm–3 or less. Having an understanding from the present study that the gas-phase hydrolysis of HFCO in the presence of H2SO4 has very limited role possibly in the absence of sunlight, we also prefer here to emphasize that the HFCO + H2O + H2SO4 reaction may occur on the surface of secondary organic aerosols for the formation of HCOOH.

Coupled cluster study of the x-ray absorption spectra of formaldehyde derivatives at the oxygen, carbon, and fluorine K-edges

We have investigated the performance of a core-valence separated scheme within the coupled cluster (CC) hierarchy of methods CC singles (CCS), CC singles and approximate doubles (CC2), and CC singles and doubles (CCSD) in reproducing the K-edge x-ray absorption spectra of the low-Z elements carbon, oxygen, and fluorine in formaldehyde (CH2O), carbonyl fluoride (CF2O), formyl fluoride (CHFO), and formic acid (CHOOH). The analysis covers the entire frequency region from the first 1s → π* excitation to the core-ionization limit, encompassing the region of Rydberg transitions. Moreover, a simulation of the vibronic progressions in the 1s → π* bands of both carbon and oxygen in formaldehyde has been performed at the core-valence separated CCSD level, and the results are critically compared with highly resolved experimental data for this molecule.

Diffraction-Detected Sum Frequency Generation: Novel Ultrafast X-ray Probe of Molecular Dynamics.

We propose a novel time-resolved diffraction technique based on sum frequency generation that combines an optical pump with an X-ray stimulated Raman probe. Simulations are presented for formyl fluoride, which is nonchiral in the ground state and evolves into a chiral nonplanar structure in the first excited state upon excitation by a circularly polarized UV pump. A coherently controlled elliptically polarized pump is used to prepare the molecule in a selected enantiomer and the chiral interconversion dynamics is then monitored by the probe diffraction.

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

Oxidation Decomposition Mechanism of Fluoroethylene Carbonate‐Based Electrolytes for High‐Voltage Lithium Ion Batteries: A DFT Calculation and Experimental Study

AbstractThe oxidative decomposition mechanism of fluoroethylene carbonate (FEC) used in high‐voltage batteries is investigated by using density functional theory (DFT). Radical cation FEC•+ is formed from FEC by transferring one electron to electrode and the most likely decomposition products are CO2 and 2‐fluoroacetaldehyde radical cation. Other possible products are CO, formaldehyde and formyl fluoride radical cations. These radical cations are surrounded by much FEC solvent and their radical center may attack the carbonyl carbon of FEC to form aldehyde and oligomers of alkyl carbonates, which is similar with the oxidative decomposition of EC. Then, our experimental result reveals that FEC‐based electrolyte has rather high anodic stability. It can form a robust SEI film on the positive electrode surface, which can inhibit unwanted electrolyte solvent and LiPF6 salts decomposition, alleviate Mn/Ni dissolution and therefore, improve the coulombic efficiency and the cycling stability of high voltage LiNi0.5Mn1.5O4 positive electrodes. This work displays that FEC‐based electrolyte systems have considerable potential replacement of the EC‐based electrolyte for the applications in 5 V Li‐ion batteries.

Theoretical Study on Gas Phase Reactions of OH Hydrogen-Abstraction from Formyl Fluoride with Different Catalysts

The mechanisms and kinetics of the gas phase reactions that the hydrogen atom in formyl fluoride (FCHO) abstracted by OH in the presence of water, formic acid (FA), or sulfuric acid (SA) are theoretically investigated at the CCSD(T)/6-311++G(3df, 3pd)//M06-2X/6-311++G(3df, 3pd) level of theory. The calculated results show that the barriers of the transition states involving catalysts are lowered to −2.89, −6.25, and −7.76 kcal/mol from 3.64 kcal/mol with respect to the separate reactants, respectively, which reflects that those catalysts play an important role in reducing the barrier of the hydrogen abstraction reaction of FCHO with OH. Additionally, using conventional transition state theory with Eckart tunneling correction, the kinetic data demonstrate that the entrance channel X⋯FCHO+OH (X=H2O, FA, or SA) is significantly more favorable than the pathway X⋯OH+FCHO. Moreover, the rate constants of the reactions of FCHO with OH radical with H2O, FA, or SA introduced are computed to be smaller than that of the naked OH+FCHO reaction because the concentration of the formed X⋯FCHO or X⋯OH complex is quite low in the atmosphere.

Vibrational energies for HFCO using a neural network sum of exponentials potential energy surface

A six-dimensional potential energy surface (PES) for formyl fluoride (HFCO) is fit in a sum-of-products form using neural network exponential fitting functions. The ab initio data upon which the fit is based were computed at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12]/cc-pVTZ-F12 level of theory. The PES fit is accurate (RMSE = 10 cm(-1)) up to 10 000 cm(-1) above the zero point energy and covers most of the experimentally measured IR data. The PES is validated by computing vibrational energies for both HFCO and deuterated formyl fluoride (DFCO) using block improved relaxation with the multi-configuration time dependent Hartree approach. The frequencies of the fundamental modes, and all other vibrational states up to 5000 cm(-1) above the zero-point energy, are more accurate than those obtained from the previous MP2-based PES. The vibrational frequencies obtained on the PES are compared to anharmonic frequencies at the MP2/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ levels of theory obtained using second-order vibrational perturbation theory. The new PES will be useful for quantum dynamics simulations for both HFCO and DFCO, e.g., studies of intramolecular vibrational redistribution leading to unimolecular dissociation and its laser control.

Vibrational Energy Levels via Finite-Basis Calculations Using a Quasi-Analytic Form of the Kinetic Energy.

A variational method for the calculation of low-lying vibrational energy levels of molecules with small amplitude vibrations is presented. The approach is based on the Watson Hamiltonian in rectilinear normal coordinates and characterized by a quasi-analytic integration over the kinetic energy operator (KEO). The KEO beyond the harmonic approximation is represented by a Taylor series in terms of the rectilinear normal coordinates around the equilibrium configuration. This formulation of the KEO enables its extension to arbitrary order until numerical convergence is reached for those states describing small amplitude motions and suitably represented with a rectilinear system of coordinates. A Gauss-Hermite quadrature grid representation of the anharmonic potential is used for all the benchmark examples presented. Results for a set of molecules with linear and nonlinear configurations, i.e., CO2, H2O, and formyl fluoride (HFCO), illustrate the performance of the method and the versatility of our implementation.

THz spectra of formyl fluoride, HFCO

Formyl fluoride, HFCO, has been observed as an impurity in the terahertz spectrum of COF 2. Ground state and ν 5 HFCO features were initially assigned based on the work of Wong et al. [M. Wong, J.W.C. Johns, A.R.W. McKellar, J. Mol. Spectrosc. 94 (1982) 79] and Xu et al. [Yunjie Xu, J.W.C. Johns, A.R.W. McKellar, J. Mol. Spectrosc. 168 (1994) 147.] A combined fit of the data reported in these references with the new rotational data reported in this work has resulted in a more extensive set of parameters for the ground and ν 5 states.

New One-Pot Synthesis of 4-Hydroxybenzaldehyde Derivatives and Picric Acid from 4-Hydroxyphenylglycine with HNO3/H2O

Since aromatic aldehydes are important intermediates in the chemical, pharmaceutical and cosmetic industries, easy and con-venient synthetic methods to synthesize them have been pur-sued. Among the most widely-used methods are formylation of aromatic compounds and oxidation of primary alcohols. Previ-ous reports describe a variety of formylation reagents, including formyl fluoride HCOF and BF