Experimental and Theoretical Study of the OH-Initiated Degradation of Piperidine under Simulated Atmospheric Conditions.

The OH-initiated photo-oxidation of piperidine and the photolysis of 1-nitrosopiperidine were investigated in a large atmospheric simulation chamber and in theoretical calculations based on CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The rate coefficient for the reaction of piperidine with OH radicals was determined by the relative rate method to be = (1.19 ± 0.

Comment on "Theoretical study of the NO radical reaction with CHClBr, CHICl, CHBrI, CHClBr, and CHClBr" by I. Alkorta, J. M. C. Plane, J. Elguero, J. Z. Dávalos, A. U. Acuña and A. Saiz-Lopez, 2022, , 14365.

This comment addresses a systematic error in the potential energy surfaces of the title reactions presented in the original article by Alkorta The NO radical has symmetry in the electronic ground state while the M08HX functional employed in the original article predicts an incorrect geometry and energy. By combining thermodynamic data for the OH + HNO → HO + NO reaction with spectroscopic data and results from M08HX calculations on HNO, HO and the OH radical, the ground state NO radical energy is estimated to be 37 kJ mol lower than reported for the geometry.

Atmospheric Chemistry of -Methylmethanimine (CHN═CH): A Theoretical and Experimental Study.

The OH-initiated photo-oxidation of -methylmethanimine, CHN═CH, was investigated in the 200 m EUPHORE atmospheric simulation chamber and in a 240 L stainless steel photochemical reactor employing time-resolved online FTIR and high-resolution PTR-ToF-MS instrumentation and in theoretical calculations based on quantum chemistry results and master equation modeling of the pivotal reaction steps. The quantum chemistry calculations forecast the OH reaction to primarily proceed via H-abstraction from the ═CH group and π-system C-addition, whereas H-abstraction from the -CH group is a minor route and forecast that N-addition can be disregarded under atmospheric conditions. Theoretical studies of CHN═CH photolysis and the CHN═CH + O reaction show that these removal processes are too slow to be important in the troposphere.

Atmospheric Chemistry of 2-Amino-2-methyl-1-propanol: A Theoretical and Experimental Study of the OH-Initiated Degradation under Simulated Atmospheric Conditions.

The OH-initiated degradation of 2-amino-2-methyl-1-propanol [CHC(NH)(CH)CHOH, AMP] was investigated in a large atmospheric simulation chamber, employing time-resolved online high-resolution proton-transfer reaction-time-of-flight mass spectrometry (PTR-ToF-MS) and chemical analysis of aerosol online PTR-ToF-MS (CHARON-PTR-ToF-MS) instrumentation, and by theoretical calculations based on M06-2X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The quantum chemistry calculations reproduce the experimental rate coefficient of the AMP + OH reaction, aligning () = 5.2 × 10 × exp (505/) cm molecule s to the experimental value = 2.

Experimental and Theoretical Study of the OH-Initiated Degradation of Piperazine under Simulated Atmospheric Conditions.

The OH-initiated photo-oxidation of piperazine and 1-nitropiperazine as well as the photolysis of 1-nitrosopiperazine were investigated in a large atmospheric simulation chamber. The rate coefficient for the reaction of piperazine with OH radicals was determined by the relative rate method to be = (2.8 ± 0.

Atmospheric Chemistry of Methyl Isocyanide-An Experimental and Theoretical Study.

The reaction of CHNC with OH radicals was studied in smog chamber experiments employing PTR-ToF-MS and long-path FTIR detection. The rate coefficient was determined to be = (7.9 ± 0.

Theoretical and Experimental Study on the Reaction of tert-Butylamine with OH Radicals in the Atmosphere.

The OH-initiated atmospheric degradation of tert-butylamine (tBA), (CH)CNH, was investigated in a detailed quantum chemistry study and in laboratory experiments at the European Photoreactor (EUPHORE) in Spain. The reaction was found to mainly proceed via hydrogen abstraction from the amino group, which in the presence of nitrogen oxides (NO ), generates tert-butylnitramine, (CH)CNHNO, and acetone as the main reaction products. Acetone is formed via the reaction of tert-butylnitrosamine, (CH)CNHNO, and/or its isomer tert-butylhydroxydiazene, (CH)CN═NOH, with OH radicals, which yield nitrous oxide (NO) and the (CH)Ċ radical.

Correction: The applicability of proton transfer reaction-mass spectrometry (PTR-MS) for determination of isocyanic acid (ICA) in work room atmospheres.

Correction for 'The applicability of proton transfer reaction-mass spectrometry (PTR-MS) for determination of isocyanic acid (ICA) in work room atmospheres' by Mikolaj Jan Jankowski et al., Environ. Sci.

Atmospheric Chemistry of (CF)CF-C≡N: A Replacement Compound for the Most Potent Industrial Greenhouse Gas, SF.

FTIR/smog chamber experiments and ab initio quantum calculations were performed to investigate the atmospheric chemistry of (CF)CFCN, a proposed replacement compound for the industrially important sulfur hexafluoride, SF. The present study determined k(Cl + (CF)CFCN) = (2.33 ± 0.

Kinetic and Theoretical Study of the Nitrate (NO3) Radical Gas Phase Reactions with N-Nitrosodimethylamine and N-Nitrosodiethylamine.

The reaction rates of (CH3)2NNO and (CH3CH2)2NNO with NO3 radicals were determined relative to formaldehyde (CH2O) and ethene (CH2CH2) at 298 ± 2 K and 1013 ± 10 hPa in purified air by long path FTIR spectroscopy. The reactions are too slow to be of importance at atmospheric conditions: kNO3+(CH3)2NNO = (1.47 ± 0.

H-Bonding of Sulfuric Acid with Its Decomposition Products: An Infrared Matrix Isolation and Computational Study of the H2SO4·H2O·SO3 Complex.

The FTIR matrix isolation spectra of H2SO4 vapors show a group of bands with synchronous growth of their relative intensities which is independent of the water species content of the matrix layer. Their frequency positions indicate that the species they represent is H-bonded and composed of all three components (H2SO4, H2O, and SO3) involved in the vapor decomposition equilibrium of the acid molecule. Structure, stabilization energies, and vibrational frequencies of several H-bonded complexes between these components were considered in B3LYP calculations employing Dunning's correlation-consistent aug-cc-pVTZ basis sets.

Experimental and Theoretical Study of the OH-Initiated Photo-oxidation of Formamide.

The kinetics of OH radical reaction with formamide was studied by the relative rate method employing proton transfer reaction-mass spectrometry detection at the European Photochemical Reactor in Valencia, Spain. The rate coefficient was determined to be (4.5 ± 0.

H-Bonding of Formic Acid with Its Decomposition Products: A Matrix Isolation and Computational Study of the HCOOH/CO and HCOOH/CO₂ Complexes.

The infrared spectra of formic acid/argon matrix layers deposited after flowing over a drying agent show distinct new bands when compared to matrix layers deposited without going through a drying process. The new bands are assigned as due to a formic acid/carbon monoxide H-bonded complex. Several complexes of HCOOH/CO/H2O and HCOOH/CO2 composition have been characterized in B3LYP and MP2 calculations.

The reactions of N-methylformamide and N,N-dimethylformamide with OH and their photo-oxidation under atmospheric conditions: experimental and theoretical studies.

The reactions of OH radicals with CH3NHCHO (N-methylformamide, MF) and (CH3)2NCHO (N,N-dimethylformamide, DMF) have been studied by experimental and computational methods. Rate coefficients were determined as a function of temperature (T = 260-295 K) and pressure (P = 30-600 mbar) by the flash photolysis/laser-induced fluorescence technique. OH radicals were produced by laser flash photolysis of 2,4-pentanedione or tert-butyl hydroperoxide under pseudo-first order conditions in an excess of the corresponding amide.

Tropospheric photolysis rates of the acetaldehyde isotopologues CD₃CHO and CD₃CDO relative to CH₃CHO measured at the European Photoreactor Facility.

Acetaldehyde is a hazardous pollutant found in indoor and ambient air. Acetaldehyde photolysis is pressure- and wavelength-dependent with three distinct product channels. In this study, the photolysis rates of CH3CHO, CD3CDO, and CD3CHO are studied in natural tropospheric conditions using long path FTIR spectroscopy, at the European Photoreactor Facility (EUPHORE) in Valencia, Spain.

Hydrogen bonding in the sulfuric acid-methanol-water system: a matrix isolation and computational study.

Frozen core MP2 and DFT computations were carried out on possible configurations of 1:1 H2SO4·CH3OH and 1:1:1 H2SO4·CH3OH·H2O complexes. Minimum energy structures, stabilization energies, H-bond lengths and vibrational frequencies were calculated. The latter complex can exist in either sequential "linear" configurations involving four H-bonds or "cyclic" structures involving three H-bonds only.

The applicability of proton transfer reaction-mass spectrometry (PTR-MS) for determination of isocyanic acid (ICA) in work room atmospheres.

A method is presented for the real-time quantitative determination of isocyanic acid (ICA) in air using proton transfer reaction-mass spectrometry (PTR-MS). Quantum mechanical calculations were performed to establish the ion-polar molecule reaction rate of ICA and other isocyanates. The PTR-MS was calibrated against different ICA air concentrations and humidity conditions using Fourier transform-infrared spectroscopy (FT-IR) as quantitative reference.

Atmospheric gas phase chemistry of CH2═NH and HNC. A first-principles approach.

Quantum chemical methods were used to investigate the OH initiated atmospheric degradation of methanimine, CH2═NH, the major primary product in the atmospheric photo-oxidation of methylamine, CH3NH2. Energies of stationary points on potential energy surfaces of reaction were calculated using multireference perturbation theory and coupled cluster theory. The results show that hydrogen abstraction dominates over the addition route in the CH2═NH + OH reaction, and that the major primary product is HCN, while HNC and CHONH2 are minor primary products.

Atmospheric fate of nitramines: an experimental and theoretical study of the OH reactions with CH3NHNO2 and (CH3)2NNO2.

The rates of CH3NHNO2 and (CH3)2NNO2 reaction with OH radicals were determined relative to CH3OCH3 and CH3OH at 298 ± 2 K and 1013 ± 10 hPa in purified air by long path FTIR spectroscopy, and the rate coefficients were determined to be k(OH+CH3NHNO2) = (9.5 ± 1.9) × 10(-13) and k(OH+(CH3)2NNO2) = (3.

Trimethylamine/sulfuric acid/water clusters: a matrix isolation infrared study.

In continuation of our studies of sulfuric acid H-bonded complexes of atmospheric relevance we report the infrared spectra of the matrix isolated complexes formed between trimethylamine and sulfuric acid. Evidence for proton transfer was anticipated for the present system, as trimethylamine ((CH3)3N) is of strong basic nature. However, the spectra of this system are complicated by the inevitable presence water in the vapor and in the matrix, resulting in matrix layers containing three species capable of forming H-bonded complexes.

Vibrational spectra, quantum chemical calculations and spectral assignments of 1,1-difluoro-1-silacyclohexane.

Raman spectra of 1,1-difluoro-1-silacyclohexane as a liquid, and as a solid at 78 K were recorded and depolarization data obtained. The infrared spectra of the vapour, liquid and amorphous and crystalline solids have been studied. In the low temperature IR and Raman spectra eight and three bands, respectively, were shifted a few cm(-1) when the sample crystallized.

Real-time monitoring of emissions from monoethanolamine-based industrial scale carbon capture facilities.

We demonstrate the capabilities and properties of using Proton Transfer Reaction time-of-flight mass spectrometry (PTR-ToF-MS) to real-time monitor gaseous emissions from industrial scale amine-based carbon capture processes. The benchmark monoethanolamine (MEA) was used as an example of amines needing to be monitored from carbon capture facilities, and to describe how the measurements may be influenced by potentially interfering species in CO2 absorber stack discharges. On the basis of known or expected emission compositions, we investigated the PTR-ToF-MS MEA response as a function of sample flow humidity, ammonia, and CO2 abundances, and show that all can exhibit interferences, thus making accurate amine measurements difficult.

Theoretical study on the formation and photolysis of nitrosamines (CH3CH2NHNO and (CH3CH2)2NNO) under atmospheric conditions.

The reactions of CH(3)CH(2)NH and (CH(3)CH(2))(2)N radicals with NO have been studied using quantum chemistry methods. The results show that formation of the nitrosamines CH(3)CH(2)NHNO and (CH(3)CH(2))(2)NNO is similar and that both isolated molecules are thermally stable. The nitrosamine formation reaction is highly exothermic, and the hot CH(3)CH(2)NHNO may undergo isomerization and subsequent reaction with O(2) to form the corresponding imine, CH(3)CH═NH.

Do primary nitrosamines form and exist in the gas phase? A computational study of CH3NHNO and (CH3)2NNO.

The reactions of the CH(3)NH and (CH(3))(2)N radicals with NO have been studied using quantum chemistry methods to compare the formation and stability of primary and secondary nitrosamines. The calculations show that the entrance part of potential energy surfaces of CH(3)NHNO and (CH(3))(2)NNO formation are similar, and it is concluded that primary amines form nitrosamines under the atmospheric conditions. CH(3)NHNO can, in contrast to (CH(3))(2)NNO, undergo isomerization via a barrier below the reactants entrance energy to CH(2)NHNOH, which through reaction with O(2) eventually leads to formation of CH(2)=NH on a short timescale.

Atmospheric chemistry and environmental impact of the use of amines in carbon capture and storage (CCS).

This critical review addresses the atmospheric gas phase and aqueous phase amine chemistry that is relevant to potential emissions from amine-based carbon capture and storage (CCS). The focus is on amine, nitrosamine and nitramine degradation, and nitrosamine and nitramine formation processes. A comparison between the relative importance of the various atmospheric sinks for amines, nitrosamines and nitramines is presented.