Ether Radical Research Articles

Density functional theory guide for copolymerization mechanism between allyl radical with radicalophile: photo-driven radical mediated [3 + 2] cyclization.

The challenge of activating inert allyl monomers for polymerization has persisted, prompting our proposal of the photo-driven radical mediated [3 + 2] cyclization reaction (PRMC). This innovative approach significantly expedites the homopolymerization of multi-allyl monomers, enabling the synthesis of embolic microspheres for hepatocellular carcinoma interventions. PRMC involves allyl monomers to form allylic radicals and then radicals participating in a cycloaddition reaction with unsaturated olefins as radicalophiles to form cyclopentane-based radical products. While extensively studied in the theoretical and experimental homopolymerization, PRMC's application in copolymerization remains unexplored. To address this knowledge gap, we explored the elementary reaction, selecting allyl methyl ether radicals (AMER) and α,β-unsaturated ketones as radicalophiles for copolymerization investigations by density functional theory (DFT) analysis. We quantified energy differences between ground and excited states of reactants, elucidated frontier molecular orbitals, and assessed thermodynamic data for copolymerization feasibility. We also evaluated the electronic properties of reactants, predicting the reactivity of radicalophiles and the interactions of intermolecular reactions. Additionally, we applied transition state theory and interaction/deformation models and conducted a local orbital analysis to comprehensively study excess electron distribution and gyration radius of cyclic radical product. Our findings offer vital insights into PRMC's potential in copolymerization. This research provides a robust theoretical foundation for practical application, enhancing the polymerization field. Based on density functional theory (DFT), the calculations were performed at the M06-2X/6-311 + + G(d,p) level in/by Gaussian 16 package. Subsequently, our analytical results apply time-dependent density-functional theory (TD-DFT) and solvent modeling (SMD). Single-point energy calculations determine the driving force behind the radicals' reaction with radicalophiles. Furthermore, we assessed the electrostatic potential (ESP) of the reactants. The results of the calculations were visualized by the Multiwfn 3.6 and VMD 1.9 programs.

Unusual Photochemistry in Aromatic Dithioimides: Quantitative Thione Reduction Promoted by Ether Solvents.

We report a mechanistic investigation of an aromatic dithioimide (2SS) displaying puzzling yet efficient photochemistry in ether solvents. Perplexingly, 2SS dissolved in ether solvents in a sealed and degassed vial was photochemically converted to the corresponding diimide (2OO), as determined by 1H NMR following product extraction. With no external sources of oxygen in the sample, could the oxygen in 2OO be from the ether itself? To study this unprecedented proposition, we attempt to uncover the ether's involvement in this reaction. As seen by laser-flash photolysis, 2SS appears to first react with the solvent from its singlet excited state. Following the reaction by NMR under rigorously oxygen- and water-free conditions led to the identification of a photoreductive pathway that quantitatively transformed one thione into a methylene to yield 2SH2. Subsequent oxidation of 2SH2 or irradiation of 2SS under air proved that molecular oxygen was indeed necessary to observe an oxidative pathway leading to 2OO, ruling out the initially proposed involvement of an ether oxygen. An explanation of 2SS desulfurization was further revealed through the study of solvent by-products by GC-MS analysis. Supported by DFT calculations, a mechanism is proposed to involve a chain reaction initiated by photochemically generated ether radical.

Synthesis of degradable polymers via 1,5-shift radical isomerization polymerization of vinyl ether derivatives with a cleavable bond

AbstractWe report a novel method for synthesizing degradable polymers based on 1,5-shift radical isomerization polymerizations of vinyl ethers with transferable atoms or groups and in-between acid-cleavable ether linkages in the side chains. In particular, vinyl ethers with side chains composed of thiocyano and p-methoxybenzyl ether groups underwent radical isomerization polymerizations via 1,5-shifts, in which a vinyl ether radical abstracted the cyano group intramolecularly to generate a thiyl radical and result in a polymer with a p-methoxybenzyl ether linkage in the main chain. The obtained polymer was easily degraded into low molecular-weight products with HCl solution. Furthermore, the copolymerization with vinyl acetate proceeded via 1,5-shift isomerization to introduce cleavable linkages in the main chains of the copolymers, which were similarly degraded.

Visible-Light-Driven Denitrogenative C–C Bond Formation and Oxidative Difunctionalization of Vinyl Azides

AbstractA newer synthetic protocol has been developed to synthesize α-oxyalkyl ketones from vinyl azides under transition-metal-free reaction conditions. The reaction proceeds in the presence of organic photoredox catalyst rose bengal, an oxidant tert-butyl hydroperoxide (TBHP), and ethers. A broad range of substituted vinyl azides were found to react smoothly upon visible-light irradiation, which readily furnished the related products. Several control experiments have been done to suggest a probable mechanism. The process is initiated by radical addition to vinyl azide, which triggers a cascade fragmentation mechanism driven by the loss of dinitrogen and the stabilized ether radical ultimately produces the α-oxyalkyl ketones. This method provides a simple, mild, straight forward, novel paradigm to prepare α-oxyalkyl ketones.

Unimolecular Reactions of 2-Methyloxetanyl and 2-Methyloxetanylperoxy Radicals.

Alkyl-substituted cyclic ethers are intermediates formed in abundance during the low-temperature oxidation of hydrocarbons and biofuels via a chain-propagating step with ȮH. Subsequent reactions of cyclic ether radicals involve a competition between ring opening and reaction with O2, the latter of which enables pathways mediated by hydroperoxy-substituted carbon-centered radicals (Q̇OOH). Due to the resultant implications of competing unimolecular and bimolecular reactions on overall populations of ȮH, detailed insight into the chemical kinetics of cyclic ethers remains critical to high-fidelity numerical modeling of combustion. Cl-initiated oxidation experiments were conducted on 2-methyloxetane (an intermediate of n-butane oxidation) using multiplexed photoionization mass spectrometry (MPIMS), in tandem with calculations of stationary point energies on potential energy surfaces for unimolecular reactions of 2-methyloxetanyl and 2-methyloxetanylperoxy isomers. The potential energy surfaces were computed using the KinBot algorithm with stationary points calculated at the CCSD(T)-F12/cc-pVDZ-F12 level of theory. The experiments were conducted at 6 Torr and two temperatures (650 K and 800 K) under pseudo-first-order conditions to facilitate Ṙ + O2 reactions. Photoionization spectra were measured from 8.5 eV to 11.0 eV in 50-meV steps, and relative yields were quantified for species consistent with Ṙ → products and Q̇OOH → products. Species detected in the MPIMS experiments are linked to specific radicals of 2-methyloxetane. Species from Ṙ → products include methyl, ethene, formaldehyde, propene, ketene, 1,3-butadiene, and acrolein. Ion signals consistent with products from alkyl radical oxidation were detected, including for Q̇OOH-mediated species, which are also low-lying channels on their respective potential energy surfaces. In addition to species common to alkyl oxidation pathways, ring-opening reactions of Q̇OOH radicals derived from 2-methyloxetane produced ketohydroperoxide species (performic acid and 2-hydroperoxyacetaldehyde), which may impart additional chain-branching potential, and dicarbonyl species (3-oxobutanal and 2-methylpropanedial), which often serve as proxies for modeling reaction rates of ketohydroperoxides. The experimental and computational results underscore that reactions of cyclic ethers are inherently more complex than currently prescribed in chemical kinetic models utilized for combustion.

Reaction mechanisms of alkyloxiranes for combustion modeling

Cyclic ethers are intermediates formed from unimolecular reaction of carbon-centered hydroperoxy-substituted radicals (̇QOOH), which are central to low-temperature chain-branching. Because cyclic ethers are isomer-specific proxies for ̇QOOH, detailed prescription of chemical reactions describing the consumption mechanisms is required for accurate combustion modeling. However, the most common approach in the development of chemical kinetics mechanisms is to use a simplified set of elementary steps that neglect the formation and subsequent reaction of cyclic ether radicals, which creates a source of mechanism truncation error. As a consequence, quantitative discrepancies between model predictions and experimental species profiles of cyclic ethers are ubiquitous and span a range of hydrocarbons such as n-butane, n-pentane, n-hexane, cyclohexane, hexene isomers, and hexanal. Moreover, uncertainties in species profile predictions of cyclic ethers translate directly to uncertainty in ignition predictions.For the explicit purpose of determining the extent to which cyclic ether consumption mechanisms affect combustion modeling, the present work examines the chemical kinetics underpinning such discrepancies using, as a representative case, a subset of cyclic ethers produced from n-butane oxidation. Detailed sub-mechanisms are developed using Reaction Mechanism Generator (RMG) for ethyloxirane and 2,3-dimethyloxirane, which form from unimolecular decomposition of β-̇QOOH radicals during n-butane combustion. The sub-mechanisms prescribe consumption reactions for both cyclic ethers, including ̇OH-initiated H-abstraction, O2-addition, RȮO isomerization, among other reactions, and were integrated with the NUIGMech1.1 mechanism to examine model predictions of species profiles and ignition delay times.Inclusion of the sub-mechanisms led to closer consistency between model predictions and experimental species profiles and also affected ignition predictions. Sensitivity analysis shows that rates of ̇OH-initiated H-abstraction are critical for determining temperature dependence of species profiles of cyclic ethers, which may serve as an indicator for the importance of branching fractions in the initiation step ̇OH + n-butane → H2O + 1‑butyl/2‑butyl. Moreover, flux towards ketohydroperoxide formation from n-butane increased upon addition of the sub-mechanisms, as determined by rate-of-production analyses conducted on ̇OH and related impact on ignition delay time simulations.The results herein demonstrate that detailed sub-mechanisms and accurate H-abstraction rates from cyclic ethers are necessary for high-fidelity predictions of chemical kinetics for combustion modeling. Continued refinement of detailed reaction mechanisms is required in order to produce accurate models for combustion that serve as a starting point for mechanism reduction techniques applied either to detailed mechanisms or to sub-mechanisms for consequent integration. Such techniques are required to enable modeling of reactive flows that incorporate computational fluid dynamics at practical conditions.

Unimolecular Reactions of 2,4-Dimethyloxetanyl Radicals.

Alkyl-substituted oxetanes are cyclic ethers formed via unimolecular reactions of QOOH radicals produced via a six-membered transition state in the preceding isomerization step of organic peroxy radicals, ROO. Owing to radical isomer-specific formation pathways, cyclic ethers are unambiguous proxies for inferring QOOH reaction rates. Therefore, accounting for subsequent oxidation of cyclic ethers is important in order to accurately determine rates for QOOH → products. Cyclic ethers can react via unimolecular reaction (ring-opening) or via bimolecular reaction with O2 to form cyclic ether-peroxy adducts. The computations herein provide reaction mechanisms and theoretical rate coefficients for the former type in order to determine competing pathways for the cyclic ether radicals. Rate coefficients of unimolecular reactions of 2,4-dimethyloxetanyl radicals were computed using master equation modeling from 0.01 to 100 atm and from 300 to 1000 K. Coupled-cluster methods were utilized for stationary-point energy calculations, and uncertainties in the computed rate coefficients were accounted for using variation in barrier heights and in well depths. The potential energy surfaces reveal accessible channels to several species via crossover reactions, such as 2-methyltetrahydrofuran-5-yl and pentanonyl isomers. For the range of temperature over which 2,4-dimethyloxetane forms during n-pentane oxidation, the following are the major channels: 2,4-dimethyloxetan-1-yl → acetaldehyde + allyl, 2,4-dimethyloxetan-2-yl → propene + acetyl, and 2,4-dimethyloxetan-3-yl → 3-butenal + methyl, or, 1-penten-3-yl-4-ol. Well-skipping reactions were significant in a number of channels and also exhibited a markedly different pressure dependence. The calculations show that rate coefficients for ring-opening are approximately an order of magnitude lower for the tertiary 2,4-dimethyloxetanyl radicals than for the primary and secondary 2,4-dimethyloxetanyl radicals. Unlike for reactions of the corresponding ROO radicals, however, unimolecular rate coefficients are independent of the stereochemistry. Moreover, rate coefficients of cyclic ether radical ring-opening are of the same order of magnitude as O2 addition, underscoring the point that a competing network of reactions is necessary to include for accurate chemical kinetics modeling of species profiles for cyclic ethers.

Exploring the Chemical Kinetics of the First Oxygen Addition to Di-n-Propyl Ether Radicals at Low Temperatures.

Linear ethers are promising biomass fuels with high volume energy density and high cetane number that may be used directly as alternative fuels or fuel additives in internal combustion engines. In this work, the first O2 addition reaction of the di-n-propyl ether radical was investigated using high-level quantum chemical calculations combined with the Rice-Ramsperger-Kassel-Marcus theory to solve the master equation. The potential energy surfaces of di-n-propyl ether radicals (C6H13O) with O2 were constructed at the QCISD(T)/CBS//M062X/6-311++G(d, p) level, and the rate constants were calculated for the pressure range of 0.1-100 atm and the temperature range of 300-1500 K and fitted by a modified Arrhenius formula. The calculations show that the consumption of di-n-propyl ether peroxyl radicals (C6H13O3) via the five-membered ring or six-membered ring transition-state reaction channel is most favorable. In addition, the low-temperature oxidation experiments of di-n-propyl ether were validated based on the calculations of the current work, and the results showed that the calculations were a good predictor of the experimental results.

Visible Light‐Induced Metal‐Free and Oxidant‐Free Radical Cyclization of (2‐Isocyanoaryl)(methyl)sulfanes with Ethers

AbstractA novel cascade cyclization of (2‐isocyanoaryl) (methyl)sulfanes and ethers is developed. With 4CzIPN as a photocatalyst and the irradiation of blue LED light, ether radicals are efficiently generated without adding any oxidant, endowing the strategy with features of oxidant‐free, metal‐free, mild reaction conditions, and operational simplicity. This strategy provides efficient approach to access various ether‐containing benzothiazoles in acceptable to good yields.

Density Functional Theory Guide for an Allyl Monomer Polymerization Mechanism: Photoinduced Radical-Mediated [3 + 2] Cyclization.

Polymerization of allyl ether monomers has previously been considered a free-radical addition polymerization mechanism, but it is difficult to achieve because of the high electron density of their double bond. To interpret the mechanism of photopolymerization, we therefore proposed a radical-mediated cyclization (RMC) reaction, which has been validated by results from quantum chemistry calculations and real-time infrared observation. Our RMC reaction begins with the radical abstracting one allylic hydrogen atom from the methylene group of allyl ether to generate an allyl ether radical with a delocalized π33 bond. Then, the radical reacts with the double bond of a second allyl ether molecule to form a five-membered cyclopentane-like ring (CP) radical. The CP radical abstracts a hydrogen atom from a third ether molecule. At last, a new allyl ether radical is generated and the next circulation as chain propagation begins. The distortion/interaction model was employed to explore the transient state of reaction, and real-time infrared was chosen to clarify the RMC reaction mechanism initiated by different photoinitiators. These results demonstrated that the RMC mechanism can give new insights into these fundamental processes.

Computational Investigation of Substituent Effects on the Formation and Intramolecular Cyclization of 2'-Arylbenzaldehyde and 2'-Arylacetophenone Oxime Ether Radical Cations.

This work describes our computational study of substituent effects on the formation and cyclization of 2'-arylbenzaldehyde and 2'-arylacetophenone oxime ether radical cations. Recent experimental work by de Lijser and co-workers has demonstrated that these reactive intermediates, which are generated through photoinduced electron transfer (PET) with a photosensitizer, undergo intramolecular cyclization to yield substituted phenanthridines. The experimental study further showed correlations between the yield of cyclized products and the Hammett σPara+ parameter of the substituent on the aryl group, with both strongly electron-withdrawing and electron-donating substituents shown to significantly reduce the product yield. By analyzing the ΔGPET associated with radical cation formation as well as the thermodynamics and kinetics of radical cation cyclization, we provide an explanation for these observations. We then computationally extend this mechanistic analysis to 2'-arylbenzaldehyde oxime ethers with substituents also present on the central benzene ring and show that such substituents generally have a larger impact on the PET-induced cyclization than those on the aryl group. Overall, this work extends our understanding of the overall scope of this photooxidative route toward substituted phenanthridines as well as makes clear predictions as to how the formation of oxime ether radical cations can be tuned by substituents.

Substitution Pattern‐Selective Olefin Cross‐Couplings

AbstractThe use of radical ions as reactive intermediates can complement polarity‐driven and neutral radical‐driven reactions in synthetic organic chemistry. The present study revealed that the reactivity of enol ether radical cations can be simply tuned by addition/removal of a methyl group, allowing development of unique substitution pattern‐selective olefin cross‐couplings. Anodically generated enol ether radical cations selectively add to appropriately substituted alkenes to afford the corresponding cycloadducts in good‐to‐excellent yields. Competition experiments using alkenes possessing two differently substituted double bonds clearly demonstrated the unique reactivity of the enol ether radical cations.

Possible Intermediacy of Cyclopropane Complexes in the Isomerization of Aliphatic Amine Radical Cations.

The isomerization of aliphatic amine radical cations via intermediate [cyclopropane-NH3]+• and [cyclopropane-amine]+• ion-neutral complexes was studied experimentally with double-focusing mass spectrometers and computationally with composite ab initio methods. The results examine and extend Audier's suggestion that primary amine radical cations with alkyl substituents at the β- and/or γ-carbon atoms isomerize via transient complexes of NH3 and alkyl cyclopropanes; these are formed by ring closure of the easily accessible γ-distonic isomers. Ionized amines with substituents at the α-carbon may react analogously when trialkyl cyclopropane complexes can be formed. Isomerization via complex intermediates is a major reaction pathway when the internal energy of the amine radical cation is less than that required for simple CC-bond cleavage. Complexes of unsubstituted or monosubstituted ionized cyclopropanes rarely contribute to the isomerization reactions. Secondary and tertiary amine radical cations do not undergo isomerization via cyclopropane intermediates, whereas aliphatic ether radical cations do.

Transformation from xanthate-type cationogen mediated metal-free RAFT cationic polymerization with “HCl·Et2O” into RAFT radical polymerization to form poly(alkyl vinyl ether)-b-polyvinyl alcohol amphiphiles

To elucidate the applicable range of metal-free RAFT cationic polymerization (MRCP) with “HCl·Et2O”, the effects of the monomer structure on the transformation from MRCP to RAFT radical polymerization were investigated. The MRCP with HCl·Et2O was conducted using the xanthate-type cationogen, O-ethyl S-(1-ethoxyethyl) carbonodithioate (EVEX) at 0 °C for alkyl vinyl ethers (ALVE) such as n-butyl (NBVE), isobutyl (IBVE), isopropyl (IPVE), and tert-butyl vinyl ethers (TBVE). It was demonstrated that EVEX acted efficiently as a RAFT cationogen for the cationic polymerization initiated by HCl·Et2O with good control over the molecular weight, polydispersity, and chain ends of the resulting poly(ALVE), regardless of the monomer structure of ALVE. The resulting chain-transfer constants indicate that EVEX is a substantially effective RAFT cationogen for MRCP of ALVE with HCl·Et2O. The resulting poly(ALVE) was utilized as a macromolecular chain transfer agent (macro-CTA) for RAFT radical polymerization since it had 0.72–0.76 of ω-end functionality for the xanthate group [–S–C(=S)OC2H5], as determined from 1H NMR and MALDI-TOF-MS spectra under the optimal conditions. However, when the resulting poly(TBVE) was employed for subsequent RAFT radical polymerization, no block copolymerization proceeded due to the poor stability of the vinyl ether radical. Thus, poly(ALVE) but not poly(TBVE) obtained by MRCP was available as a macro-CTA for RAFT radical polymerization to synthesize novel block copolymers such as poly(IPVE)-b-poly(vinyl acetate). In addition, the selectively saponified block copolymer, poly(IPVE)-b-polyvinyl alcohol, formed spherical micelles in water, demonstrating the successful results of the one-pot transformation from MRCP to RAFT radical polymerization.

Oxime Ether Radical Cations Stabilized by N‐Heterocyclic Carbenes

AbstractN‐heterocyclic carbene (NHC) nitric oxide (NHCNO) radicals, which can be regarded as iminoxyl radicals stabilized by NHCs, were found to react with a series of silyl and alkyl triflates to generate the corresponding oxime ether radical cations. The structures of the resulting oxime ether radical cations were determined by X‐ray crystallography, along with EPR and computational analysis. In contrast, lutidinium triflate produced a 1:1 mixture of [NHCNO+][OTf−] and [NHCNHOH+][OTf−] upon the reaction with NHCNO. This study adds an important example of stable singlet carbenes for stabilizing main‐group radicals because of their π‐conjugating effect, the synthesis and structures of which have not been reported previously.

Oxime Ether Radical Cations Stabilized by N-Heterocyclic Carbenes.

N-heterocyclic carbene (NHC) nitric oxide (NHCNO) radicals, which can be regarded as iminoxyl radicals stabilized by NHCs, were found to react with a series of silyl and alkyl triflates to generate the corresponding oxime ether radical cations. The structures of the resulting oxime ether radical cations were determined by X-ray crystallography, along with EPR and computational analysis. In contrast, lutidinium triflate produced a 1:1 mixture of [NHCNO+ ][OTf- ] and [NHCNHOH+ ][OTf- ] upon the reaction with NHCNO. This study adds an important example of stable singlet carbenes for stabilizing main-group radicals because of their π-conjugating effect, the synthesis and structures of which have not been reported previously.

Hydrolysis of radicals and molecules of ethers

Radiolysis of aqueous solutions of diisopropyl and methyl tert-butyl ethers under γ-irradiation has been studied. The effect of pH on the products yield has been investigated. It has been shown that the rate constants of ether radicals hydrolysis are ~109 times higher than these of ether molecules in acidic as well as basic medium.

Theoretical investigation on the decomposition reaction mechanisms and kinetics of methyl vinyl ether initialized by OH radical

The reaction energy profiles of the cis-methyl vinyl ether and OH radical were investigated theoretically with QCISD(T)/aug-cc-pvtz//M06-2X/6-311++G(d,p) method. Five hydrogen abstraction and two addition/elimination reaction paths were explored. The results show that all the hydrogen abstractions are feasible with energy barriers less than 36.7 kJ mol−1, while the initial association of MVE and OH is able to produce highly stable intermediates followed by some subsequent reactions with moderate energy barriers. The high-pressure limit rate constants were evaluated with the canonical variational transition-state theory or the Rice–Ramsperger–Kassel–Marcus theory with tunneling correction in the temperature region 200–2000 K. The results are in very good agreement with the available experimental detections at 299, 352 and 427 K. The atmospheric half-life of MVE simulated with a typical initial concentration of an experiment is estimated to be 5.51 h and is consistent with the observed data 5.18 h. The reaction rate calculations indicate that the title reaction is essentially a fast reaction and is kinetics-controlled. The consumption rate of MVE decreases with increasing temperature in 300–700 K and increases in 800–2000 K, showing that the addition/elimination reactions are dominant at lower, while the hydrogen abstractions are at higher temperatures. The concentration distributions of the products examined in this work show that the stable intermediates IM1 and IM2 have the highest concentrations in about 300–400 K, while glycolaldehyde (HOCH2CHO) is the main product in 500–1300 K. At higher temperatures above 1400 K, radical CH2OCH=CH2 is found as the main product.

Closed-system pyrolysis of butyl ethyl ether and sec-butyl ethyl ether at 20 MPa—Mechanistic insights

Natural macromolecular organic matter (kerogen) possesses a complex structure with a variety of subunits with a multitude of functional groups (e.g. numerous ether bonds). During thermal maturation, a preferential cleavage of labile bonds leads to fragmentation and the gradual liberation of CO2, H2O and organic compounds (e.g., hydrocarbons). Though, a detailed understanding of the kinetics and mechanisms of individual thermochemical reactions during maturation is difficult due to the complex structure, but would enable an improved prediction of the composition of released organic products or gas pressures. Pyrolysis studies of organic model compounds are one approach for a better understanding of individual bond cleavage pathways in kerogen and for the derivation of kinetic parameter.Here we present the results of closed-system pyrolysis experiments of the model compounds butyl ethyl ether (BEE) and sec-butyl ethyl ether (SBEE) at elevated pressure (20MPa) and temperatures (150–345°C).C1–C4 alkanes and carbonyl compounds (CO or butanone) account for the pyrolysis’ main products together with alkenes as byproducts. A detailed radical chain reaction mechanism is proposed to explain the formation pathways of the main products. The activation energy for H abstraction from CH bonds in the ether model compounds controls the formation of favored ether radicals whose decomposition gives rise to the main products. CO2 and several esters are byproducts whose formation can be attributed to the reaction of alkoxy radicals with CO or aldehydes – or to some extent ether decomposition processes induced by oxygen impurities.

Ether Degradation Thermodynamics in Li-O2 Redox Environments: A Computational Study

The reaction thermodynamics of the 1,2-dimethoxi-ethane (DME) in a highly oxidizing environment has been studied by first principles methods to predict the spontaneous degradation processes of this model solvent molecule commonly used in electrolytes for Li-O2 rechargeable batteries. The potential energy surfaces of the reactivity of DME towards the O2 - superoxide radical anion in oxygen-poor or oxygen rich environments have been calculated by quantum chemistry techniques. A large set of density functional theory (DFT) methods has been used and compared to post-Hartree-Fock predictions to evaluate their predictive relative performances and select the best for the calculation of the full reactivity. Solvation effects have been considered by employing self-consistent reaction field in a continuum solvation model. The onset reaction of the degradation of the DME model molecule is the H-extraction by the O2 - superoxide anion to form an ether radical with an unpaired electron on a carbon atom. The subsequent reactivity of this radical molecule differs depending on the availability of molecular oxygen molecules. In oxygen rich environment this radical species follow multistep paths to give formaldehyde and alkyl carbonates whereas in oxygen poor environment the final products are alkyl oxalates or alkyl formates.