sverrlo

• Løyland, Sverre & Uggerud, Einar (2024). Competing Reaction Pathways in Gas-Phase Oxidation of C<inf>6</inf>H<inf>6</inf> by Protonated H<inf>2</inf>O<inf>2</inf>. Journal of Physical Chemistry A. ISSN 1089-5639. 128(49), s. 10465–10473. doi: 10.1021/acs.jpca.4c03722. Fulltekst i vitenarkiv Vis sammendrag

  Reactions between protonated hydrogen peroxide and benzene (and benzene-d6) have been studied in the gas phase using an FT-ICR mass spectrometer. Four competing paths for the bimolecular system were identified, namely, proton transfer, hydride abstraction, dissociative single-electron transfer, and an electrophilic addition of HO+ to give the Wheland intermediate [C6H6, OH]+ followed by a subsequent elimination of water. The three latter pathways correspond to three different ways to oxidize benzene. All reaction mechanisms have been modeled using quantum chemical methods, and the calculations are in agreement with the experimental observations. The total reaction rate proceeds at collision rate (slightly higher than the calculated Langevin capture rate), which exemplifies the high reactivity of H3O2+ toward arenes. These observations demonstrate a much richer chemical landscape than previously inferred from the corresponding condensed phase reaction, where only electrophilic substitution by solvated HO+ was described.

• Qureishy, Thomas; Løyland, Sverre; Jørgensen, Susanne Jøntvedt; Færgestad, Eline Mosleth; Norby, Truls & Uggerud, Einar (2022). Mechanisms for sonochemical oxidation of nitrogen. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 24(25), s. 15357–15364. doi: 10.1039/d2cp01995g. Fulltekst i vitenarkiv Vis sammendrag

  N2O, and mixtures of N2 and O2, dissolved in water—both in the presence and absence of added noble gases—have been subjected to ultrasonication with quantification of nitrite and nitrate products. Significant increase in product formation upon adding noble gas for both reactant systems is observed, with the reactivity order Ne < Ar < Kr < Xe. These observations lend support to the idea that extraordinarily high electronic and vibrational temperatures arise under these conditions. This is based on recent observations of sonoluminescence in the presence of noble gases and is inconsistent with the classical picture of adiabatic bubble collapse upon acoustic cavitation. The reaction mechanisms of the first few reaction steps necessary for the critical formation of NO are discussed, illustrated by quantum chemical calculations. The role of intermediate N2O in this series of elementary steps is also discussed to better understand the difference between the two reactant sources (N2O and 2 : 1 N2 : O2; same stoichiometry).

Se alle arbeider i NVA

• Fængsrud, Vibeke Gwendoline; Hansen, Nikolai Bjørnestøl; Holter, Karl Erik & Løyland, Sverre (2016). GeoGebra- og exceloppskrifter Matematikk 2P. House of Math AS. ISBN 9788283370300. 49 s. Fulltekst i vitenarkiv
• Fængsrud, Vibeke Gwendoline; Hansen, Nikolai Bjørnestøl; Holter, Karl Erik & Løyland, Sverre (2016). GeoGebraoppskrifter Matematikk S1. House of Math AS. ISBN 9788283370348. 56 s. Fulltekst i vitenarkiv
• Fængsrud, Vibeke Gwendoline; Hansen, Nikolai Bjørnestøl; Holter, Karl Erik & Løyland, Sverre (2016). GeoGebraoppskrifter Matematikk R2. House of Math AS. ISBN 9788283370331. 52 s. Fulltekst i vitenarkiv
• Fængsrud, Vibeke Gwendoline; Hansen, Nikolai Bjørnestøl; Holter, Karl Erik & Løyland, Sverre (2016). GeoGebraoppskrifter Matematikk S2. House of Math AS. ISBN 9788283370355. 55 s. Fulltekst i vitenarkiv
• Fængsrud, Vibeke Gwendoline; Hansen, Nikolai Bjørnestøl; Holter, Karl Erik & Løyland, Sverre (2016). GeoGebra- og exceloppskrifter Matematikk 1P. House of Math AS. ISBN 9788283370294. 57 s. Fulltekst i vitenarkiv
• Fængsrud, Vibeke Gwendoline; Hansen, Nikolai Bjørnestøl; Holter, Karl Erik & Løyland, Sverre (2016). GeoGebra- og exceloppskrifter Matematikk U. House of Math AS. ISBN 9788283370362. 36 s. Fulltekst i vitenarkiv
• Fængsrud, Vibeke Gwendoline; Hansen, Nikolai Bjørnestøl; Holter, Karl Erik & Løyland, Sverre (2016). GeoGebraoppskrifter Matematikk 1T. House of Math AS. ISBN 9788283370317. 52 s. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Løyland, Sverre & Uggerud, Einar (2023). Mechanistic insight into the industrial production of H₂O₂ using mass spectrometry. Fulltekst i vitenarkiv Vis sammendrag

  The anthraquinone process is an industrial, catalytic process for the production of hydrogen peroxide, H₂O₂, from hydrogen and oxygen gas. First, an anthraquinone, 1, is catalytically hydrogenated with palladium and hydrogen gas to form an anthrahydroquinone, 2. The reduced molecule 2 is subsequently oxidized back to 1 by spontaneous reaction with oxygen gas, and in the process forming H₂O₂. Although more than 4 million tons of H₂O₂ are produced yearly, the reaction mechanism for the formation of H₂O₂ from 2 is not understood in detail, and the mechanisms presented in most textbooks are probably wrong as they are spin-forbidden. We have performed reactions between a cationic derivative of 2 and O2 gas in the collision cell of a mass spectrometer in conjunction with quantum chemical computations to elucidate the mechanism. As the samples of 2 react with atmospheric oxygen in seconds, the experiments also present some challenging practical aspects of mass spectrometric analyses of reactive molecules.

• Løyland, Sverre (2023). Introduction to mass spectrometry for physical chemistry. Fulltekst i vitenarkiv Vis sammendrag

  Mass spectrometry is a powerful tool for qualitative and quantitative analysis. However, it is less known for its use in physical chemistry. This talk will introduce the basic concepts of physical mass spectrometry to investigate bonding, thermochemistry and reaction mechanisms. Chemical reactions are not limited to glassware. Reactions can also be performed in the collision cell of a mass spectrometer by colliding ions with reactant gases. By studying the product ion intensities at different collision energies, one can learn about kinetics, reaction mechanisms, potential energy surfaces and dynamics. Similarly, collisional activation of reactant ions with inert gases to produce fragment ions at varying collision energies give information about the intrinsic properties of the ion such as ligand binding energies. Since reactions in the collision cell are inherently unimolecular or bimolecular without complicating factors as solvents, they lend themselves to comparison with quantum chemical computations and can be modelled using theories for unimolecular reactions rates.

• Løyland, Sverre (2021). On the hunt for short-lived high-valent iron-oxo species. Fulltekst i vitenarkiv
• Løyland, Sverre (2021). Lyden av god kjemi. Fulltekst i vitenarkiv
• Løyland, Sverre (2020). Sonokjemi: Lyden av god kjemi. Fulltekst i vitenarkiv
• Løyland, Sverre (2019). Simple Models for Biological CO₂-fixation: Gas-Phase Carboxylation of Deprotonated Glycolaldehyde and Its Reverse Analogs. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  In this work a simple model for biological CO₂-fixation by RuBisCO has been studied where the usual C₅-substrate has been replaced by the C₂-carbohydrate glycolaldehyde in its deprotonated form which is the simplest ion with the same functionality as the actual substrate. The model system was studied both experimentally using physical mass spectrometry and quantum chemical calculations. It was found that carboxylation happens without a barrier, but the reaction is not selective and forms both carboxylates and carbonates. However, when the model system is extended with a Mg²⁺-cation similar to how RuBisCO incorporates a divalent cation at the active site, calculations show that the reaction becomes selective to formation of the carboxylate. The reverse reaction was also studied, that is decarboxylation of tartronate semialdehyde and its isomers. Since tartronate semialdehyde is not commercial and attempts at synthesizing it were unsuccessful, are arguments against the existence of the compound in bulk presented. Its isomer hydroxypyruvate was studied instead and the experimental barriers of decarboxylation agree well with calculations.

Se alle arbeider i NVA