- Evidence Against Ion-pair Formation in the Reactions of Ethyl Halides with Silver Salts
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Contrary to a previous report, the product ratio from the reaction of ethyl iodide with silver nitrate in ethanol varies with the salt concentration; the product ratios obtained are very similar to those for the corresponding SN2 reactions of triethyloxonium hexafluorophosphate.
- Kevill, Dennis N.,Fujimoto, Edward K.
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Read Online
- Kinetics and Products of the Reactions of Ethyl and n-Propyl Nitrates with OH Radicals
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The kinetics of the reactions of ethyl (1) and n-propyl (2) nitrates with OH radicals has been studied using a low-pressure flow tube reactor combined with a quadrupole mass spectrometer. The rate constants of the title reactions were determined under pseudo–first-order conditions from kinetics of OH consumption in high excess of nitrates. The overall rate constants, k1 = 1.14 × 10?13 (T/298)2.45 exp(193/T) and k2 = 3.00 × 10?13 (T/298)2.50 exp(205/T) cm3 molecule?1 s?1 (with conservative 15% uncertainty), were determined at a total pressure of 1 Torr of helium over the temperature range (248–500) and (263–500) K, respectively. The yields of the carbonyl compounds, acetaldehyde and propanal, resulting from the abstraction by OH of an α-hydrogen atom in ethyl and n-propyl nitrates, followed by α-substituted alkyl radical decomposition, were determined at T = 300 K to be 0.77 ± 0.12 and 0.22 ± 0.04, respectively.
- Morin, Julien,Bedjanian, Yuri,Romanias, Manolis N.
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p. 822 - 829
(2016/11/02)
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- Vapor generation of inorganic anionic species after aqueous phase alkylation with trialkyloxonium tetrafluoroborates
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Aqueous phase reaction of trialkyloxonium tetrafluoroborates, R 3O+BF4- (R=Me, Et) has been tested in the alkylation of simple inorganic anionic substrates such as halogen ions, cyanide, thiocyanate, sulphide an
- D'Ulivo, Alessandro,Pagliano, Enea,Onor, Massimo,Pitzalis, Emanuela,Zamboni, Roberto
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experimental part
p. 6399 - 6406
(2010/04/06)
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- FTIR spectroscopic study of the OH-induced oxidation of two linear acetates: Ethyl and n-propyl acetates
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OH-induced oxidation mechanisms of ethyl and n-propyl acetates have been investigated at room temperature (298 ± 5 K) and atmospheric pressure by photolysing CH3ONO/acetate/NO mixtures with FTIR spectroscopy as analytical device. The main oxidation products and their yields were as follows: from ethyl acetate, acetic acid (0.75 ± 0.13), acetoxyacetaldehyde (0.15 ± 0.05), acetic anhydride (0.02 ± 0.01), formic acetic anhydride (0.02 ± 0.01) and peroxyacetyl nitrate (PAN); from n-propyl acetate, acetoxyacetaldehyde (0.22 ± 0.06), formic acetic anhydride (0.28 ± 0.03), acetic acid (0.15 ± 0.02), acetaldehyde (0.35 ± 0.10), peroxypropionyl nitrate (PPN) and probably acetoxypropionaldehyde (0.30 ± 0.10). From these data, oxidation schemes of these two acetates were elucidated. This study reveals in particular the specifc reactivity of acetates by confirming the novel α-ester rearrangement proposed recently by Tuazon et al. (J. Phys. Chem. A, 1998, 102, 2316) and then by showing that oxygenated alkoxyl radicals may not follow the same rules of reactivity as other alkoxyl radicals. This last observation shows the necessity for further experiments to understand the influence of the oxygenated function on alkoxyl reactivity.
- Picquet-Varrault,Doussin,Durand-Jolibois,Carlier
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p. 2595 - 2606
(2007/10/03)
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- Formation of nitrogenous compounds in the photooxidation of n-butane under atmospheric conditions
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The photooxidation of n-butane under atmospheric conditions in the presence of NOx resulted in the formation of the following nitrogenous products: peroxy acetyl nitrate 23, sec-butyl nitrate 16, n-butyl nitrate 1.3, ethyl nitrate 1.3, peroxy n-butyryl nitrate 1.3, and peroxy propionyl nitrate 0.5% of the initially added odd nitrogen. In addition, an electron capturing compound eluting at the retention time of sec-propyl nitrate was also observed accounting for 5% of initial NOx. Butan-2-one was the major product of conversion of n-butane with a yield of 37%. From product ratios it is evident that the formation of sec-butyl nitrate is favored over that of n-butyl nitrate by a factor of 2.1. The rate of reaction of sec-butoxy radicals with oxygen is equal to their decomposition rate.
- Evmorfopoulou, Efthalia,Glavas, Sotirios
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p. 1151 - 1159
(2007/10/03)
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- Nitration of alcohols by nitryl fluoride
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A general method for the preparation of nitrates by treatment of alcohols with nitryl fluoride (FNO2) in MeCN in the presence of KF has been developed.
- Fedorov,Eremenko
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p. 1022 - 1023
(2007/10/03)
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- Formation and Thermal Decomposition of Butyl-Substituted Peroxyacyl Nitrates: n-C4H9C(O)OONO2 and i-C4H9C(O)OONO2
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The butyl-substituted peroxyacyl nitrates n-C4H9C(O)OONO2 and i-C4H9C(O)OONO2 have been synthesized in the liquid phase, prepared in-situ in the gas phase by sunlight irradiation of aldehyde-NO mixtures, measured by electron capture gas chromatography, and characterized in a number of gas-phase and liquid-phase tests. Gas-phase yields as a fraction of initial NO were 0.39 for the n-butyl isomer and 0.20 for the isobutyl isomer. The corresponding gas-phase aldehyde oxidation mechanisms are outlined. Thermal decomposition in the presence of excess NO yielded n-butanal and isobutanal as the major carbonyl products. Thermal decomposition rates at ambient temperature and atmospheric pressure are comparable to that of PAN , with k298 = 1.8E-4 s-1 for n-C4H9C(O)OONO2 and 2.4E-4 s-1 for i-C4H9C(O)OONO2. Emission data for precursor hydrocarbons indicate C4H9C(O)OONO2/PAN ambient concentration ratios of 0.19 in urban air. Atmospheric implications for the formation and removal of C4H9C(O)OONO2 are briefly discussed.
- Grosjean, Daniel,Grosjean, Eric,Williams, Edwin L.
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p. 1099 - 1105
(2007/10/03)
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- Rate Constants for the Reactions of CH3O and C2H5O with NO2 over a Range of Temperature and Total Pressure
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The kinetics of the reactions of CH3O and C2H5O radicals with NO2 have been studied using pulsed laser photolysis to create the radicals from the corresponding alkyl nitrite and by time-resolved, laser-induced fluorescence to observe the decay of the radical concentration.At 295 K, rate constants for CH3O+NO2 have been measured in the presence of Ar (6-100Torr), He(30-100 Torr) and CF4 (30-125 Torr).The association reaction to CH3ONO2 appears to predominate, and rate constants in the limit of low and high pressure are deduced: (k0/10E-29 cm6 molecule-2 s-1) =2.8+/-0.6(M=Ar); 1.6 +/- (M=He); 3.4+/-1.0(M=CF4), and (kinfinite/10E-11 cm3 molecule-1 s-1)=2.0+/-0.4, where the quoted errors correspond to two standard deviations.A limited number of measurements is also reported for this reaction at 390K.The rate of the reaction of C2H5O with NO2 at 295 K is found to be same in the presence of 15 and 100 Torr of Ar, and the measurements yield a rate constant: (kinfinite/10E-11 cm3 molecule-1 s-1) =2.8+/-0.3.
- Frost, Michael J.,Smith, Ian W. M.
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p. 1751 - 1756
(2007/10/02)
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- SUBSTITUTED HETEROCYCLYL-PHENYLFORMAMIDINES AND SALTS THEREOF
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Compounds of the formula STR1 wherein R is hydrogen or methyl;R 1 is straight or branched alkyl of 1 to 6 carbon atoms, hydroxy(alkyl of 1 to 6 carbon atoms), mono-or di-(alkoxy of 1 to 6 carbon atoms)(alkyl of 1 to 6 carbon atoms), (alkyl of 1 to 6 cabon atoms) thio(alkyl of 1 to 6 carbon atoms), cyano(alkyl of 1 to 6 carbon atoms), alkenyl, alkynyl, or cycloalkyl;R 2 is hydrogen, alkyl of 1 to 3 carbon atoms, alkoxy of 1 to 3 carbon atoms or halogen; andX is pyrazol-3-yl, 1,2,4-triazol-3-yl, pyridin-2-yl, pyridin-3-yl, thiazol-4-yl, 2-methyl-thiazol-4-yl or 2-methylamino-thiazol-4-yl;tautomers thereof, and non-toxic, pharmacologiically acceptable acid addition salts thereof. The compounds as well as their salts are useful as antiulcerogenics and gastric acid secretion inhibitors.
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- Formation of Organic Nitro-compounds in Flowing H2O2+NO2+N2+Organic Vapour Systems. Part 3.-Effects of O2 Addition on H2O2+NO2+N2+Alkane Systems
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The effects of oxygen on the product distribution from the surface-initiated reactions in flowing mixtures of H2O2, NO2, N2 and RH, where RH=ethane, propane, n-butane and n-pentane, at 298 K have been studied.In the absence of O2, the principal products are the corresponding nitroalkane, alkyl nitrite and alkyl nitrate.In the presence of sufficiently large concentrations of O2, the predominant product is the alkyl nitrate and the only other products of significance, in some cases, are the corresponding carbonyl compounds.The variation of the product yields with / gives values for the rate-constant ratios k8/(k3+k4) for reaction at both primary and secondary radical sites:.Possible mechanisms by which the products are formed are discussed.
- Baulch, Donald L.,Campbell, Ian M.,Chappel, Jonathan M.
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p. 617 - 628
(2007/10/02)
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- Formation of Organic Mitro-compounds in Flowing H2O2+NO2+N2+Organic Vapour Systems. Part 1.-Surface Initiation Efficiency and Reactions of Ethane
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When H2O2 vapour is added to an excess of NO2 in a flow system with ethane as the carrier gas in the presence of a boric-acid-coated surface at temperatures in the range 298-363 K, the organic products are niroethane, ethyl nitrate and smaller amounts of ethyl nitrite.On the basis of the initiating steps the total yield of nitro-compounds, extrapolated to =0, provides a direct measure of the H2O2 to OH conversion efficiency in step(1).This is shown to correspond to that indicated by the previously applied indirect method involving measurement of the variation of CO2 yields with the ratio / in H2O2+NO2+CO systems containing diethyl ether (S) as the internal kinetic calibrant.This efficiency does not change significantly throughout the above temperature range.The mechanism of formation of the nitrocompounds involves the following competitive steps: .Arguments are presented that step (8) may proceed by way of partial dissociation of chemically activated C2H5ONO molecules rather than by bimolecular O-abstraction route.A rate constant of k4=(1.3+/-0.2)xE10 dm3mol-1s-1 is obtained for the reaction at ambient temperature for M=C2H6 at a pressure of 40 kPa.
- Audley, Gary J.,Baulch, Donald L.,Campbell, Ian M.
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p. 599 - 608
(2007/10/02)
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- Formation of Organic Nitro-compounds in Flowing H2O2+NO2+N2+Organic Vapour Systems. Part 2.-H2O2+NO2+N2+Alkane System
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The principal products from the surface-initiated reactions in flowing mixtures of H2O2, NO2,N2 and RH, where RH=ethane, propane, n-butane and n-pentane, have been identified as the nitroalkane, alkyl nitrite and alkyl nitrate.The product yields have been measured; in the case of propane the variation of the yields with total gas pressure has also been studied.Values have been obtained for the relative rates of primary and secondary H-atom abstraction from each alkane by OH and for the rate-constant ratios k3/k4 and k5/k6 at 298 K:.The trends in the product yields with the variation of pressure and change of R indicate that RO radicals are produced via reactions (4)-(6) rather than by a single-step reaction of R with NO2.
- Baulch, Donald L.,Campbell, Ian M.,Chappel, Jonathan M.
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p. 609 - 616
(2007/10/02)
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- Kinetics and Mechanism for the Alkaline Homogeneous Hydrolysis of 1,1,1-Trimethylolethane Trinitrate
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The kinetics for the alkaline homogeneous hydrolysis of 1,1,1-trimethylolethane trinitrate (MTN) in 95percent ethanol-water with sodium hydroxide concentrations between 0.25 and 2.1 M and temperatures between 50.0 and 60.0 degC have been investigated.One mole of MTN was found to react with 3 mol of base and to hydrolize by a series of consecutive and competitive bimolecular and internal cyclization reactions involving three nitrate ester intermediates to form the cyclic alcohol ether 3-methyl-3-oxetanemethanol (AE) as the final major product with only trace amounts of the expected trialcohol 1,1,1-tris(hydroxymethyl)ethane (TA).MTN and its intermediates showed good second-order rate constants for the expression -d(MTN)/dt = k1(MTN) = k2(B-)(MTN), where k1 is the first-order rate constant with excess base, B-.Relative k2 values in 95percent ethanol-water, 95percent methanol-water, and water were found to be 1.0, 0.1, and 0.01, respectively.Hydrolysis kinetics and product formation for each nitrate ester intermediate have been determined, and an overall hydrolysis mechanism for MTN is presented.
- Hoffsommer, John C.,Glover, Donald J.,Burlinson, Nicholas E.
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p. 315 - 321
(2007/10/02)
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- ON THE INTERACTION BETWEEN DIALKYL PHOSPHITES AND METAL SALTS
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The interaction between dialkyl phosphites (RO)2P(O)H where R= CH3, C2H5, C4H9 and metal salts MeX2 where Me= Zn, Ca, Co, Mn, Cd and X= Cl, NO3 and CH3COO was studied.It was found that the reaction depends on the substitutes in the dialkyl phosphites as well as on the nucleophilicity of the metal salts.The monoalkyl phosphorous acid esters of the following general formula were obtained: RO-P(O)H-O-Me-O-P(O)H-OR
- Troev, K.,Borisov, G.
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p. 267 - 282
(2007/10/02)
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- Alkyl Nitrate Formation from the NOx-Air Photooxidations of C2-C8 n-Alkanes
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The yields of alkyl nitrates formed in the NOx-air photooxidations of the homologous series of n-alkanes from ethane through n-octane have been determined at 299 +/- 2 K and 735 torr total pressure for two different chemical systems.Alkyl peroxy radicals were generated by reaction of the n-alkanes with OH radicals (generated from the photolysis of methyl nitrite in air) or Cl atoms (from photolysis of Cl2 in air).The alkyl nitrate yields obtained from the two systems, corrected for secondary reactions, were in agreement within the experimental errors and increased monotonically with the carbon number of the n-alkane, from x-air photooxidations of the large n-alkanes.
- Atkinson, Roger,Aschmann, Sara M.,Carter, William P. L.,Winer, Arthur M.,Pitts, James N.
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p. 4563 - 4569
(2007/10/02)
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- A New Method for the Synthesis of Nitroethane, Ethyl Nitrite, and Ethyl Nitrate
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When H2O2 vapour and NO2 are mixed in an ethane carrier in a flow system in the presence of a boric acid-coated surface, ethyl nitrate, nitroethane, and some ethyl nitrite are synthesized; a mechanism is advanced in which OH* and C2H5* radicals are the intermediates.
- Audley, Gary J.,Baulch, Donald L.,Campbell, Ian M.
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p. 1053 - 1055
(2007/10/02)
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- Direct vs. Indirect Mechanisms in Organic Electrochemistry. Estimates of Activation Energies for Hydrogen Atom Transfer Processes of Relevance in Indirect Mechanisms Using the Bond Energy-Bond Order (BEBO) and Equibonding Methods
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Activation energies for a number of hydrogen abstraction reactions of interest in mechanistic organic electrochemistry have been calculated using the bond energy-bond-order (BEBO) and equibonding method.The main emphasis has been put on processes with bearing on the problem of deciding between direct and indirect mechanisms in anodic oxidation, viz. acyloxylation, hydroxylation, methoxylation, nitrooxylation, cyanation, carbomethoxylation and azidation.The results indicate that indirect mechanisms might play a more important role than presently assumed.
- Eberson, Lennart
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p. 481 - 492
(2007/10/02)
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