Methyl Propyl Ether Research Articles

Leveraging Ion Pairing and Transport in Localized High-Concentration Electrolytes for Reversible Lithium Metal Anodes at Low Temperatures.

Coulombic efficiency of over 99 % is rarely achieved for Li metal anode below -40 °C, hindering the practical application of high-energy-density Li metal batteries under extreme conditions. Herein, limiting factors for Li metal reversibility are investigated utilizing ether-based localized high-concentration electrolytes of different solvent-diluent combinations. We find that along with the desolvation barrier, bulk ion transport properties including ionic conductivity, transference number, and diffusivity are also crucial factors for low-temperature Li deposition behavior. Superior Li metal reversibility was observed within the combination of the solvent with moderately weak solvating power and the diluent with minimal viscosity, highlighting the role of ion transport and the necessity for a trade-off with desolvation. The optimized electrolyte composed of lithium bis(fluorosulfonyl)imide, methyl n-propyl ether, and 1,1,2,2-tetrafluoroethyl methyl ether delivers exceptional Coulombic efficiency of 99.34 % at -40 °C and 98.96 % at -60 °C under a current density of 0.5 mA cm-2. Furthermore, Li||LiCoO2 (2.7 mAh cm-2) cells demonstrate impressive reversible capacity and cycling stability at these temperatures. This work sheds light on the less-recognized relevance of bulk ion transport to low-temperature performance and provides guidelines for the electrolyte design of Li metal batteries operating in cold environments.

OH radical and Cl atom initiated Reactions of Methyl n-propyl ether: Kinetics and Atmospheric Implications

Oxygenated volatile organic compounds (OVOCs) are emitted into the atmosphere via biological processes, oxidation of hydrocarbons, evaporation of oxygenated solvents or fuels and incomplete combustion of hydrocarbon-fueled sources. In the troposphere, the degradation mechanisms of these VOCs are triggered by oxidising agents like Cl atoms and OH radicals. In the present work, the kinetics were investigated for the reactions of methyl n-propyl ether (MPE) with OH radicals and Cl atoms using pulsed laser photolysis-laser induced fluorescence and relative rate techniques, respectively, in the range of 278–363 K. No significant temperature-dependence was observed for the reaction of MPE with OH radicals, whereas a slight negative temperature-dependence was asserted in the Cl reaction. The rate coefficients were also determined computationally at the CCSD(T)/aug-cc-pVDZ//M06-2X/6-311+G(d,p) and CCSD(T)/6-31+G(d,p)//BHandHLYP/6-31+G(d,p) level of theories over 250–400 K for the OH- and Cl-initiated reactions of MPE, respectively. The Arrhenius expressions for the title reactions determined are: kMPE+OHPLP−LIF(T=278−363K)=(1.36±0.21)×10−11exp[(−86±48)T] cm3 molecule−1 s−1 and kMPE+ClRR(T=278−363K)=(2.97±0.49)×10−11exp[(617±51)T] cm3 molecule−1 s−1. The rate coefficients were estimated using SAR and compared to the experimentally and computationally determined kinetic data. The products formed in the reactions were detected using the GC-MS. The atmospheric lifetimes of MPE were estimated, accounting for the rate coefficients of both reactions. The impacts of MPE emissions on the atmosphere are discussed using important atmospheric parameters.

Linear ether-based highly concentrated electrolytes for Li-sulfur batteries.

Li-S batteries have attracted attention as next-generation rechargeable batteries owing to their high theoretical capacity and cost-effectiveness. Sparingly solvating electrolytes hold promise because they suppress the dissolution and shuttling of polysulfide intermediates to increase the coulombic efficiency and extend the cycle life. This study investigated the solubility of polysulfide (Li2S8) in a range of liquid electrolytes, including organic electrolytes, highly concentrated electrolytes, and ionic liquids. The Li2S8 solubility was well correlated with the donor number (DNNMR), estimated via23Na-NMR, and was lower than 100 mM_(elemental sulfur) in electrolytes with DNNMR < 14, regardless of the type of electrolyte. Highly concentrated electrolytes comprising lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and linear chain dialkyl ethers such as methyl propyl ether (MPE), n-butyl methyl ether (BME), and ethyl propyl ether (EPE) were studied as sparingly solvating electrolytes for Li-S batteries. Monomethyl ethers, such as BME, showed more pronounced Li-ion coordination and higher ionic conductivity, whereas the steric hindrance of the longer alkyl chains in EPE lowered the solvation number, enhanced ion association, and lowered the ionic conductivity despite the solvents having similar dielectric constants. The charge-discharge rate capabilities of Li-S cells with dialkyl ether-based electrolytes were more impressive than those of cells with a localized high-concentration electrolyte using sulfolane (SL) and hydrofluoroether (HFE), [Li(SL)2][TFSA]-2HFE. The higher rate performance was attributed to the superior Li-ion transport properties of the dialkyl ether-based electrolytes. A pouch-type cell using lightweight [Li(BME)3][TFSA] demonstrated an energy density exceeding 300 W h kg-1 under lean electrolyte conditions.

Oxidation and pyrolysis of methyl propyl ether

AbstractThe ignition, oxidation, and pyrolysis chemistry of methyl propyl ether (MPE) was probed experimentally at several different conditions, and a comprehensive chemical kinetic model was constructed to help understand the observations, with many of the key parameters computed using quantum chemistry and transition state theory. Experiments were carried out in a shock tube measuring time variation of CO concentrations, in a flow tube measuring product concentrations, and in a rapid compression machine (RCM) measuring ignition delay times. The detailed reaction mechanism was constructed using the Reaction Mechanism Generator software. Sensitivity and flux analyses were used to identify key rate and thermochemical parameters, which were then computed using quantum chemistry to improve the mechanism. Validation of the final model against the 1–20 bar 600–1500 K experimental data is presented with a discussion of the kinetics. The model is in excellent agreement with most of the shock tube and RCM data. Strong non‐monotonic variation in conversion and product distribution is observed in the flow‐tube experiments as the temperature is increased, and unusually strong pressure dependence and significant heat release during the compression stroke is observed in the RCM experiments. These observations are largely explained by a close competition between radical decomposition and addition to at different sites in MPE; this causes small shifts in conditions to lead to big shifts in the dominant reaction pathways. The validated mechanism was used to study the chemistry occurring during ignition in a diesel engine, simulated using Ignition Quality Test (IQT) conditions. At the IQT conditions, where the MPE concentration is higher, bimolecular reactions of peroxy radicals are much more important than in the RCM.

Theoretical study of H-atom abstraction reactions from CH3CH2OCH2CH3, CHF2CF2OCH2CF3 and CF3CH2OCH3 by NO3 radical & subsequent degradation

The nocturnal reactions of CH3CH2OCH2CH3, CHF2CF2OCH2CF3 and CF3CH2OCH3 initiated by NO3 radicals are important sources of alkyl radicals and nitric acids. In this paper, the thermodynamics and kinetics of CH3CH2OCH2CH3, CHF2CF2OCH2CF3 and CF3CH2OCH3 induced by NO3 radical in gas phase are studied in detail by BHandHLYP method combined with 6-311G(d,p) basis set, and the single point correction is calculated by relatively accurate CCSD(T) method. In the temperature range of 200–400 K, the rate constants of title reactions are fitted to the three-parameter Arrhenius formula:k1 = 1.13 × 10−40T9.24exp(1675.99/T)k2 = 2.23 × 10−23T2.81exp(-4476.24/T)k3 = 5.63 × 1043T−19.20exp(-9344.12/T)All the rate constants calculated by the canonical variational transition state theory and the small curvature tunneling are basically consistent with the limited experimental data. By comparing the reaction rate constants of ethyl ether and its isomer methyl propyl ether with NO3 radical at 293 ± 2 K, the higher the symmetry is, the faster the reaction rate of ether is.Thermodynamic calculations and kinetic data of the title reactions indicate that the H-abstraction reactions at the –OCH2- sites are the main reaction pathways. The thermodynamic and kinetic data of the reaction CH3CH2OCH2CH3, CHF2CF2OCH2CF3 with NO3 radical, showing that the reaction activity could be reduced due to the addition of fluorine atoms, which is further verified by the enthalpies, Gibbs free energies of the title reactions and C–H bond dissociation energies of the CH3CH2OCH2CH3, CHF2CF2OCH2CF3 and CF3CH2OCH3 molecules. The reaction thermodynamics and kinetics are determined, and the formation mechanisms of the products are proposed, which are crucial to determine the influence of CH3CH2OCH2CH3, CHF2CF2OCH2CF3 and CF3CH2OCH3 on air quality, as well as its atmospheric lifetime and durability.The atmospheric lifetimes of CH3CH2OCH2CH3, CHF2CF2OCH2CF3 and CF3CH2OCH3 are evaluated in the NO3-concentration range of 5 × 108-2 × 109 molecule cm−3 to fully consider the effects of different regions on their nocturnal migration. The radiation efficiency and global warming potentials (GWPs) have been reported. The products of title reaction CH3CH2OCHCH3, CF3CHOCF2CHF2 and CF3CHOCH3 are further oxidized into organic nitrates in the presence of O2 and NO. Organic nitrites can be isomerized into organic nitrates or degraded to form CH3C(O•)HOCH2CH3, CF3C(O•)HOCF2CHF2 and CH3C(O•)HOCF3 alkoxy radicals and NO2. This work provides deep insight into the night migration and transformation mechanism of the three ethers.

Hydrogen abstraction by NO2 from asymmetric methyl ethers: A theoretical investigation

Hydrogen abstraction by NO2 from asymmetric methyl ethers by NO2 is theoretically investigated based on first-principles calculations in order to constrain their combustion models, including methyl ethyl ether(MEE), methyl n-propyl ether (MNPE), methyl i-propyl ether (MIPE), methyl n-butyl ether (MNBE), and methyl t-butyl ether (MTBE). We obtain the rate constants and branching ratios at 500–2000 K, and the dependence of reactivity on ether sizes and the reaction sites on the ethers. The cis-HONO channel is the most important one, followed by the HNO2 and trans-HONO channels. On the hand, the size of alkyl and the reaction site significantly affect the reactivity. Hydrogen abstraction mainly occurs at the C site (adjacent to the ether bond) of the long-chain alkyl. Moreover, the linear Bell-Evans-Polanyi correlation is observed for the hydrogen abstraction reactions between the asymmetric methyl ether and NO2.

Quantum chemical study on the reaction mechanism and kinetics of Cl-initiated oxidation of methyl n-propyl ether

Oxidation of methyl n-propyl ether (CH3CH2CH2OCH3) molecule initiated by Cl atoms has been carried out using a dual level of quantum chemical investigation to understand the mechanistic pathways and kinetics of the H-atom abstraction reaction. Firstly, geometry optimization and frequency calculations for all the species are performed using BHandHLYP/6-311++G(d,p) level of theory at 298 K, and energetic calculations are further refined using CCSD(T) method with the same basis set to explore all stationary points on potential energy profile. We have observed from the energy profile that H-atom abstraction from –OCH2 group of CH3CH2CH2OCH3 is the kinetically predominant pathway. The reported bond dissociation energy for the dominant path is found to be in good agreement with the experimentally determined value. Further, standard Gibbs free energies (ΔG°298) and standard enthalpies (ΔH°298) analyses also indicate that the H-atom abstraction from –OCH2 group of CH3CH2CH2OCH3 is thermodynamically more favourable than other abstraction channels. The rate coefficients are also reported using canonical transition state theory, which is found to be in good agreement with the experimental data. The atmospheric lifetime of title molecule is also calculated.

Gas-Phase Reaction of Methyl n-Propyl Ether with OH, NO3, and Cl: Kinetics and Mechanism.

Rate constants at room temperature (293 ± 2 K) and atmospheric pressure for the reaction of methyl n-propyl ether (MnPE), CH3OCH2CH2CH3, with OH and NO3 radicals and the Cl atom have been determined in a 100 L FEP-Teflon reaction chamber in conjunction with gas chromatography-flame ionization detector (GC-FID) as the detection technique. The obtained rate constants k (in units of cm3 molecule-1 s-1) are (9.91 ± 2.30) × 10-12, (1.67 ± 0.32) × 10-15, and (2.52 ± 0.14) × 10-10 for reactions with OH, NO3, and Cl, respectively. The products of these reactions were investigated by gas chromatography-mass spectrometry (GC-MS), and formation mechanisms are proposed for the observed reaction products. Atmospheric lifetimes of the studied ether, calculated from rate constants of the different reactions, reveal that the dominant loss process for MnPE is its reaction with OH, while in coastal areas and in the marine boundary layer, MnPE loss by Cl reaction is also important.

Adsorption of Inhalation Anesthetics (Fluranes and Ethers) on Activated Carbons and Zeolites at Trace Level Concentrations

This paper presents adsorption isotherms and desorption data of halogenated ethers (desflurane, isoflurane, and sevoflurane), which are used as inhalation anesthetics, and aliphatic ethers (diethyl ether and methyl propyl ether) from a nitrogen carrier gas stream. The isotherms were measured at 25 °C and 1 bar. Desorption was analyzed at temperatures between 25 and 250 °C. Zeolites with different structure and aluminum content as well as activated carbons with different pore size distributions were used as adsorbents. The analysis of the adsorption isotherms and the desorption data focuses on the interactions between adsorptive molecules and adsorbents’ surfaces. We discuss the specific influence of the molecular structure and polarity of the adsorptives as well as of the pore structure and surface chemistry of the adsorbents.

Dehydration of n-propanol and methanol to produce etherified fuel additives

An ether is an organic compound that consists of an oxygen atom bonded to two alkyl or aryl groups. In this work, we investigate the bimolecular dehydration of two alcohols, n-propanol and methanol with catalysts that are used in transesterification. Experiments were carried out to evaluate the feasibility of promoting etherification reaction using methanol and n-propanol as model alcohols. When methanol and n-propanol are reacted together, three types of ethers can be produced; i.e., dimethyl ether, methyl-propyl ether (also referred to as methoxypropane), and di-propyl ether. The latter two ethers are of more fuel interest due to their ability to stay in liquid phase at room temperature; however, the ability of catalysts to selectively produce liquid ethers is not established. Initial studies were conducted to discern the effect of sulfuric acid, amberlyst-36 and titanium isopropoxide, catalysts that are known to be effective for transesterification, at four levels of temperature on the substrate conversion, ether yield and selectivity using n-propanol. Subsequent studies with n-propanol and methanol additionally looked at the impact of select catalyst concentrations and reaction conditions. Studies indicate that liquid mixtures of 1-methoxypropane and di-propyl ethers could be formed by reacting n-propanol and methanol in the presence of sulfuric acid or Amberlyst 36. Higher concentrations of sulfuric acid (5% w/w) coupled with higher temperatures (>140 °C) favored substrate conversion and ether yields. However, it was revealed that the selectivity toward specific ethers, i.e., coupling of the two larger alcohols to produce di-propyl ether vs larger one with the smaller one to produce methoxypropane could be controlled by appropriate selection of the catalyst. We anticipate the results being a starting point for a simple technique to produce specific ethers using a mixture of alcohols that could be applied for applications such as transesterification byproduct utilization.

Kinetics and site requirements of ether disproportionation on γ-Al2O3

Measured rates of methyl propyl ether (MPE), an asymmetric ether, conversion on γ-alumina at 623K verify that hydration rates are negligible compared to disproportionation rates below 2.0kPa of water.Steady state kinetic measurements establish that diethyl ether (DEE) disproportionation rates possess reaction orders between 0 and 1. A mechanism for DEE disproportionation in which ethanol monomers and reactive ethoxy species are the primary surface species is consistent with measured pressure dependencies. The intrinsic rate constant of DEE disproportionation is nearly identical to that of unimolecular ethanol dehydration, revealing the similarity in the rate-limiting steps of these two reactions. In-situ pyridine titration studies verify that DEE disproportionation and unimolecular ethanol dehydration possess similar site requirements and densities (0.3 and 0.2 sitesnm−2, respectively) while bimolecular ethanol dehydration occurs on a separate pool of catalytic sites.

Rate Constant Calculations of H-Atom Abstraction Reactions from Ethers by HȮ2 Radicals

In this work, we detail hydrogen atom abstraction reactions from six ethers by the hydroperoxyl radical, including dimethyl ether, ethyl methyl ether, propyl methyl ether, isopropyl methyl ether, butyl methyl ether, and isobutyl methyl ether, in order to test the effect of the functional group on the rate constant calculations. The Møller-Plesset (MP2) method with the 6-311G(d,p) basis set has been employed in the geometry optimizations and frequency calculations of all of the species involved in the above reaction systems. The connections between each transition state and the corresponding local minima have been determined by intrinsic reaction coordinate calculations. Energies are reported at the CCSD(T)/cc-pVTZ level of theory and include the zero-point energy corrections. As a benchmark in the electronic energy calculations, the CCSD(T)/CBS extrapolation was used for the reactions of dimethyl ether + HȮ2 radicals. A systematic calculation of the high-pressure limit rate constants has been performed using conventional transition-state theory, including asymmetric Eckart tunneling corrections, in the temperature range of 500-2000 K. The one dimensional hindrance potentials obtained at MP2/6-311G(d,p) for the reactants and transition states have been used to describe the low frequency torsional modes. Herein, we report the calculated individual, average, and total rate constants. A branching ratio analysis for every reaction site has also been performed.

Uso de modelagem molecular no estudo dos conceitos de nucleofilicidade e basicidade

Molecular modeling enables the students to visualize the abstract relationships underlying theoretical concepts that explain experimental data on the molecular and atomic levels. With this aim we used the free software Arguslab 4.0.1 (semi-empirical method) to study the reaction of 1-chloropropane with ethoxide in solution, known to lead to methyl propyl ether, through the SN2 mechanism, and propene, through the E2 mechanism. This tool allows users to calculate some properties (i. e. heat formation or electric charges) and to produce 3D images (molecular geometry, electrostatic potential surface, etc.) that render the comprehension of the factors underlying the reaction's progress, which are related to the structure of the reagents, and the process kinetic clearer and easier to understand by the students

In Situ IR Spectroscopy and Ab Initio Calculations To Study Polymer Swelling by Supercritical CO2

The CO(2) sorption and polymer swelling of hydroxytelechelic polybutadiene (HTPB) and poly(ethylene glycol) (PEG) have been investigated as a function of temperature and CO(2) pressure by combining in situ near-infrared spectroscopy with molecular modeling. The results reported here for the PEG-CO(2) system are in a very good agreement with literature data hence validating our experimental procedure. It has been found that CO(2) sorption and swelling effect is more important for PEG than for HTPB. For both polymers, an increase of temperature leads to a strong decrease of both the CO(2) sorption and swelling. In order to identify at a molecular level the nature and strength of intermolecular interaction occurring between CO(2) and the polymers, ab initio calculations have been performed on model structures, representative of the main functional group of the polymer, and their complex with CO(2). Trans-3-hexene (3-Hex), propyl methyl ether (PME) and methoxytrimethylsilane (MTMS) have been selected to mimic the functional groups of HTPB, PEG and polydimethyl siloxane (PDMS), respectively. The last system has been chosen since previous works on the swelling of PDMS by high pressure CO(2) have revealed the high ability of CO(2) to swell both uncrosslinked and crosslinked PDMS. The calculated stabilization energies of the MTMS-CO(2), PME-CO(2), and 3-Hex-CO(2) dimers indicate that CO(2) interacts specifically with the three moieties through a Lewis acid-Lewis base type of interaction with the energies displaying the following order: E(MTMS-CO(2)) = -3.59 > E(PME-CO(2)) = -3.43 > E(3-Hex-CO(2)) = -2.5 kcal/mol. Since the solubility of CO(2) in the corresponding homopolymers follows the same order, it is evidenced that the stronger the interaction between CO(2) and the polymer, the higher the CO(2) sorption. Therefore, even if one cannot exclude the influence of free volume and chain flexibility of the polymer, it appears that the solubility of CO(2) in the polymer is predominantly governed by the interaction between CO(2) and the polymer. Although the same trend is observed for the swelling of the polymer as a function of the CO(2) pressure, we have found that for a given value of CO(2) sorption, the swelling of the polymer depends on its nature, meaning that the swelling is not only governed by the CO(2)-polymer interaction but also by other intrinsic properties of the polymer.

Dipole oscillator strength distributions, properties and dispersion energies for the dimethyl, diethyl and methyl–propyl ethers1

Isotropic dipole oscillator strength distributions (DOSDs) have been constructed for the dimethyl, diethyl and methyl–propyl ether molecules through the use of quantum mechanical constraint techniques and experimental dipole oscillator strength data. The constraints are furnished by molar refractivity data and the Thomas–Reiche–Kuhn sum rule. The DOSDs are used to obtain recommended values for a variety of isotropic dipole oscillator strength sums, logarithmic dipole oscillator strength sums, and mean excitation energies for the molecules. Pseudo-DOSDs for the ethers are also constructed and used to obtain reliable results for the isotropic dipole–dipole dispersion energy coefficients for all two-body interactions of the ethers with each other and with fifty other species. In addition reliable results are also obtained for the triple–dipole dispersion energy coefficients for all three-body interactions involving the ethers. 1Dedicated to Anthony Stone, an excellent scientist and friend, on the occasion of his 70th birthday.

Vapor−Liquid Equilibrium Data for the Binary Decafluoropentane (HFC-43-10meec) + Heptane, Decafluoropentane + Butyl Ethyl Ether, Octafluorobutane (HFC-338pcc) + Butyl Ethyl Ether, and Heptafluoro Propyl Methyl Ether (HFE-347mcc) + HFC-338pcc Systems at 101.3 kPa

Isobaric vapor−liquid equilibria were measured for the four binary systems of decafluoropentane (HFC-43-10meec) + heptane, decafluoropentane + butyl ethyl ether, octafluorobutane (HFC-338pcc) + butyl ethyl ether, and heptafluoro propyl methyl ether (HFE-347mcc) + HFC-338pcc systems at atmospheric pressure. The HFC-43-10meec + heptane system formed a minimum-boiling azeotrope. The experimental data were correlated by the Wilson and NRTL models. The Wilson and NRTL equations gave similar results.

The external-anomeric torsional effect

The rotational barrier for a methyl group at the end of an anomeric system is sometimes lower than we might have anticipated. Thus, in the trans–trans conformation of dimethoxymethane, the barrier to methyl rotation is calculated (B3LYP/6-311++G(2d,2p)) to be 2.22 kcal/mol, just slightly smaller than the corresponding barrier to rotation of the methyl group in methyl propyl ether of 2.32 kcal/mol. However, if the methyl being rotated in dimethoxymethane is placed into a gauche conformation, that rotational barrier is reduced to 1.52 kcal/mol. This substantial (0.80 kcal/mol relative to methyl propyl ether) reduction in barrier height in the latter case is attributed mainly to the change in the bond order of the C–O bond to which the methyl is attached, as a function of conformation, which in turn is a result of the anomeric effect. We have called this barrier lowering the external-anomeric torsional effect. This effect is apparently widespread in carbohydrates, and it results in the changing of conformational energies by up to about 2 kcal/mol. If polysaccharide potential surfaces are to be accurately mapped by molecular mechanics, this effect clearly needs to be accounted for.

Experimental and theoretical study on the structure and reactions of 1-methoxypropane radical cations

Structure and mechanism of thermal and photochemical reactions of radical cations of methyl n-propyl ether (MPE) were studied in irradiated freonic matrices CFCl3, CF2ClCFCl2, and CF3CCl3 at 77 K. The quantum chemical calculations of the structure of radical cations and products of their transformations were carried out with methods based on the density functional theory (DFT). Experimental and calculation results show that the MPE radical cations are characterized by substantial delocalization of spin density to the propyl group. The action of light on the MPE radical cations in a CF3CCl3 matrix at 77 K results in intramolecular rearrangement yielding the distonic radical cation .CH2CH2CH2(OH+)CH3. It was found that the primary MPE radical cations underwent irreversible transformation to CH3CH2CH2OCH2. radical as a result of an ion-molecule reaction that occurred in a CF2ClCFCl2 matrix upon heating the sample to 110–120 K or in a CFCl3 matrix upon increasing the solute concentration.

Quantitative photoabsorption of methyl propyl ether in the UV, VUV and soft X-ray regions (5–200 eV)

Absolute photoabsorption oscillator strengths (cross-sections) in the valence-shell discrete and continuum regions methyl propyl ether CH3OC3H7 have been measured from 5 to 32 eV using high-resolution (∼0.05 eV fwhm) dipole (e,e) spectroscopy. Wide-range spectra, spanning the UV, VUV and soft X-ray regions, have also been obtained at low-resolution (∼1 eV fwhm) from 5 to 200 eV for methyl propyl ether, and these wide-range spectra have been used to determine the absolute oscillator strength scales by employing valence-shell TRK (i.e., S(0)) sum-rule normalization. Evaluations of the S(−2) sum using the presently reported absolute differential photoabsorption oscillator strength data give a static dipole polarizability for methyl propyl ether in good agreement with previously reported polarizability values. Other dipole sums S(u), (u=−1,−3,−4,−5,−6,−8,−10), and logarithmic dipole sums L(u), (u=−1 to −6), are also determined from the presently reported absolute differential photoabsorption oscillator strength data using dipole sum-rules. The presently reported absolute photoabsorption oscillator strength data for methyl propyl ether (and all other atoms and molecules we have studied) are web-accessible at ftp.chem.ubc.ca/pub/cooper.

The SCO (OCS) edward—lemieux effect is controlled by a P‐orbital on oxygen. Evidence from electron momentum spectroscopy, photoelectron spectroscopy, X‐ray crystallography, and density functional theory

AbstractThe nature of the lone pairs in the series of molecules methyl propyl sulfide, dimethylthiomethane, methyl thiomethyl ether (MTME), dimethoxy‐methane, and methyl propyl ether has been examined experimentally by the techniques of electron momentum spectroscopy and photoelectron spectroscopy. Although the HOMO of MTME is found to be a p‐orbital on sulfur, it is the p‐orbital on oxygen that controls the Edward—Lemieux effect (the anomeric effect) in this molecule through a combination of both stabilizing and destabilizing interactions with C–S orbitals.