Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of interstellar medium, but formation mechanism even their simplest building block—the benzene molecule—has remained elusive for decades. Here we demonstrate crossed molecular beam experiments combined with electronic structure statistical calculations that (C 6 H ) can be synthesized via barrierless, exoergic reaction ethynyl radical 1,3-butadiene, C 2 + CCHCHCH → H,...

Ketohydroperoxides are important in liquid-phase autoxidation and gas-phase partial oxidation pre-ignition chemistry, but because of their low concentration, instability, various analytical chemistry limitations, it has been challenging to experimentally determine reactivity, only a few pathways known. In the present work, 75 elementary-step unimolecular reactions simplest γ-ketohydroperoxide, 3-hydroperoxypropanal, were discovered by combination density functional theory with several...

Rhodopsins are seven α-helical membrane proteins that of great importance in chemistry, biology, and modern biotechnology. Any silico study on rhodopsin properties functioning requires a high-quality three-dimensional structure. Due to particular difficulties with obtaining protein structures from the experiment, prediction structure based only its primary sequence is an especially important task. For last few years, significant progress was made field prediction, for methods comparative...

ABSTRACT Automatic kinetic mechanism generation, virtual high‐throughput screening, and automatic transition state search are currently trending applications requiring exploration of a large molecule space. Large‐scale requires fast accurate estimation molecules' properties interest, such as thermochemistry. Existing approaches not satisfactory for polycyclic molecules: considering the number molecules being screened, quantum chemistry (even cheap density functional theory methods) can be...

We present for the very first time single collision experimental evidence that a methyl-substituted polycyclic aromatic hydrocarbon (PAH)-2-methylnaphthalene-can be formed without an entrance barrier via indirect scattering dynamics through bimolecular of two non-PAH reactants: para-tolyl radical and vinylacetylene. Theory shows this reaction is initiated by addition to either terminal acetylene carbon (C(4)) or vinyl (C(1)) leading eventually distinct intermediates. Importantly, at C(1) was...

Crossed molecular beam experiments and electronic structure calculations on the reaction of meta-tolyl radical with vinylacetylene were conducted to probe formation methyl-substituted naphthalene isomers. We present compelling evidence that under single collision conditions 1- 2-methylnaphthalene can be formed without an entrance barrier via indirect scattering dynamics through a bimolecular two non-PAH reactants: vinylacetylene. The calculations, at UCCSD(T)-F12b/cc-pVDZ//UM06-2x/cc-pVTZ +...

Ab initio CCSD(T)/cc-pVTZ//B3LYP/6-311G** calculations of the C(5)H(5) potential energy surface have been performed to investigate reaction mechanism ethynyl radical (C(2)H) with C(3)H(4) isomers, allene and methylacetylene. They were followed by RRKM rate constants product branching ratios under single-collision conditions. The results show that C(2)H + CH(2)CCH(2) in a case statistical behavior is expected produce 1,4-pentadiyne (56-63%), ethynylallene (22-24%), pentatetraene (10-15%),...

Detailed kinetic models (DKMs) are the most fundamental "bottom-up" approaches to computational investigation of pyrolysis and oxidation fuels. The weakest points existing DKMs incomplete information about reaction types that can be involved in potential energy surfaces (PESs) processes. Also, thermodynamic parameters available literature vary widely with level theory employed. More sophisticated require improvement both our knowledge type reactions consistency parameters. In this paper, we...

Reaction dynamics: Crossed molecular beam experiments and ab initio electronic structure calculations on the reaction of ethynyl radical with isoprene are reported. The picture shows a flux contour map [D1]ethynyl forming [D1]toluene atomic hydrogen at collision energy 51.3 kJ mol−1.

Crossed molecular beam reactions of p-tolyl (C7H7) plus 1,3-butadiene (C4H6), 1,3-butadiene-d6 (C4D6), and p-tolyl-d7 (C7D7) (C4H6) were carried out under single-collision conditions at collision energies about 55 kJ mol(-1). 6-Methyl-1,4-dihydronaphthalene was identified as the major reaction product formed fractions 94% with monocyclic isomer (trans-1-p-tolyl-1,3-butadiene) contributing only 6%. The is initiated by barrierless addition radical to terminal carbon atom via a van der Waals...

Ab initio CCSD(T)/cc-pVTZ(CBS)//B3LYP/6-311g(d,p) calculations of the C(5)H(6)N potential energy surface have been performed to investigate reaction mechanism cyano radical (CN) with C(4)H(6) isomers 1- and 2-butyne 1,2-butadiene. They were followed by RRKM rate constants product branching ratios under single-collision conditions in 0-5 kcal/mol collision range. With assumption equal probabilities barrierless terminal central addition 1-butyne, 2-cyano-1,3-butadiene + H, cyanoallene CH(3)...

H-Shifts in the alkyl chain catalyzed by an aromatic ring (green pathway).

Ab initio CCSD(T)/cc-pVTZ(CBS)//B3LYP/6-311G** calculations of the C(6)H(7) potential energy surface are combined with RRKM reaction rate constants and product branching ratios to investigate mechanism distribution in C(2)H + 1-butyne/2-butyne reactions. 2-Ethynyl-1,3-butadiene (C(6)H(6)) H ethynylallene (C(5)H(4)) CH(3) predicted be major products 1-butyne reaction. The is initiated by barrierless ethynyl additions acetylenic C atoms depend on collision direction initial attack....

The crossed molecular beams reaction of ground state cyano radicals (CN) with diacetylene (HCCCCH) was studied in the laboratory under single collision conditions. Combining derived center-of-mass translational energy and angular distributions novel electronic structure calculations, we show that linear cyanodiacetylene molecule (HCCCCCN) is sole product. Our study provided no substantiation two alternative products which have been suggested previously: cyanoacetylene (HCCCN), speculated to...

Abstract The current study undertaken by the Walkerton Clean Water Centre (WCWC) is to evaluate application of Advanced Oxidation Processes (AOPs) involving Ozone and UV with addition hydrogen peroxide, as one methods used in process removal PPCPs EDCs, or taste odor. amount peroxide much higher than that ozone application. concern impact on chlorine residual water pumped distribution system. One deal this problem increase maintain required residual. That could disinfectant by-products...

The crossed molecular beam reactions of the <italic>meta</italic>-tolyl radical with 1,3-butadiene and D6-1,3-butadiene were conducted at collision energies 48.5 kJ mol⁻¹ 51.7 mol⁻¹.

Reaktionsdynamik: Die Reaktion des Ethinylradikals mit Isopren wurde mithilfe gekreuzter Molekularstrahlen und von Ab-initio-Elektronenstrukturberechnungen untersucht. Das Bild zeigt die Höhenlinienkarte für [D1]Ethinylradikals zu [D1]Toluol atomarem Wasserstoff bei einer Kollisionsenergie 51.3 kJ mol−1.

The OH initiated oxidation of nitric oxide (NO) is an important atmospheric reaction being, during the day time, main channel that leads to formation HONO a reservoir species for both and odd nitrogen. This work reports ab initio study Potential Energy Surface (PES) NO + using density functional theory calculations conducted at B3LYP level with 6-311g (d,p) basis set. We confirmed experimental observations pointing out this HONO. From addition cis trans isomers were found be formed as stable...