Unimolecular reactions of ionized methyl allyl ether

The fragmentation of CH₂?CHCH₂OCH₃^+· cation-radicals has been investigated by means of ²H- and ¹³C-labelling experiments and by analysis of collision-induced dissociation spectra. Metastable C₄H₈O^+· species decompose via one of three main channels which involve loss of (a) a hydrogen atom, (b) a methyl radical or (c) a formaldehyde molecule. Extensive, but not complete, exchange of the hydrogen and deuterium atoms in specifically labelled C₄H₈-_nD_nO^+· analogues precedes each of the three fragmentation pathways. The role of distonic ions in the rearrangement steps which bring about hydrogen exchange is discussed. The influence of isotope effects on the relative rates of the major reactions and the associated kinetic energy releases is examined. Only loss of a hydrogen atom is subject to a substantial isotope effect. Elimination of a methyl radical releases a large amount of kinetic energy, as is shown by the broad and dish-topped appearance of the corresponding metastable peak (T_1/2 ≈ 42 kJ mol^?1). The carbon atom of the original methoxy group is specifically expelled in this process. Both the large T_1/2 value and the unusual site selectivity are atypical of methyl and other alkyl radical losses from ionized alkenyl methyl ethers. The carbon atom of the methoxy group also participates specifically in formaldehyde elimination, but the two hydrogen atoms are not always selected from the three contained in the initial methoxy group. The implications of these labelling results for the synchronicity of concert of formaldehyde loss, which can be formu lated as a pericyclic process, is analysed.     

Initiated oxidation of dibutyl ether in the presence of inhibitors

It was found that unlike ionol, amines effectively inhibit the oxidation of dibutyl ether. The stoichiometric inhibition coefficient for amines is close to two. During the initiated oxidation of dibutyl ether in the presence of inhibitors, an exchange takes place of cyanoisopropyl peroxy radicals for the peroxy radicals of dibutyl ether. The mechanism of the reaction with p-phenylenediamine (p-PDA) probably consists in the formation of a fairly stable complex consisting of an amine molecule and two peroxy radicals. This reaction does not result in the formation of a hydroperoxide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1268–1273, June, 1990.     

Solubility of carbazole in binary chloroalkane + dibutyl ether solvent mixtures

Solubilities are reported for carbazole in three binary chloroalkane + dibutyl ether solvent mixtures at 25°C. Results of these measurements are compared with solution models developed for solubility in systems containing specific solute-solvent interactions. A simple model based on a single 1:1 carbazole:dibutyl ether complex described the solubility data, though the calculated equilibrium constant was about one-half of values published previously. A more sophisticated solution model, which assumes both carbazole:dibutyl ether and carbazole:chloroalkane complexes, was needed to thermodynamically describe the systems studied. Equilibrium constants for three presumed carbazole:chloroalkane complexes are calculated from measured carbazole solubilities.     

Measurement of the decomposition rate constant of azodiisobutyronitrile to radicals in dibutyl ether

Conclusions The rate constant for the decomposition of azodiisobutyronitrile into radicals was measured in dibutyl ether at 60°C. This value proved to be less than the literature value for aromatic hydrocarbons by a factor of 1.5.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1904–1906, August, 1988.     

Radiochemical study of gas-phase reactions of nucleogenic diethylgermyl cations with dibutyl ether and 1-butanol

Reactions of tritium-labeled free diethylgermyl cations with dibutyl ether and 1-butanol in a gas phase were studied by the radiochemical method. Mechanisms of the corresponding ion-molecular reactions were suggested, and the most probable paths of the cation (C₂H₅)₂TGe⁺ conversion into other isomeric forms were shown.     

Reactions of 2-aminobenzothiazoles with phenyl glycidyl ether

In acidic media 2-aminobenzothiazole and its derivatives react with phenyl glycidyl ether at the ring nitrogen atom, while in alkaline media they react at the exocyclic nitrogen atom. The structures of the compounds were proved by spectral methods and alternative synthesis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 685–691, May, 1991.     

Reactions of selenium bromides with butyl vinyl ether

Russian Journal of Organic Chemistry -     

Reactions of phenyllithium with lithium aluminum hydride in diethyl ether

Reactions of phenyllithium with LiAlH₄ in diethyl ether have been studied in detail. Lithium hydride, as an insoluble solid, and LiAlPh_n H_4?n (where n = 2 or 3)_in solution, are formed when the PhLi to LiAlH₄ ratio is 2/1and 3/1. However, Li₃AlH₆ is formed when LiAlH₄ is added to an equimolar solution of PhLi in diethyl ether. The integrity of the products have been established by IR, NMR and X-ray powder diffraction pattern.     

Electrochemical Study of Phase-Transfer Catalysis Reactions: The Williamson ether synthesis

The transfer properties of the ionic species involved in the Williamson ether synthesis by phase-transfer catalysis were investigated using electrochemical techniques developed for the study of polarised liquid/liquid interfaces. This approach allows the measurement of the apparent partition coefficients of the transferring species. From these data, it is proposed that the role of the phase-transfer catalyst salt in the reaction mechanism is to establish a Galvani distribution potential difference between the two phases which in turn acts as the driving force for transferring the reactive aqueous ions to the organic phase.     

Reactions of tetracarbonylcobaltate(-I) with chlorosilanes in ether solvents

The reactions of NaCo(CO)₄ with Me_nSiCl_4?n (n = 0–3) in diethylether (Et₂O) and in tetrahydrofuran (THF) have been studied. Three distinct reaction pathways were recognised which depend on the acidity of the chlorosilane and basicity of solvent. Attack at the silicon centre via the Co atom of Co(CO)₄^? leads to formation of a SiCo bond; reaction involving a CO ligand of Co(CO)₄^? gives clusters R₃SiOCCo₃(CO)₉; and chlorosilane induced attack of Co(CO)₄^? on the solvent gives products derived from THF molecules.     

Reactions of the ionized enol tautomer of acetanilide: elimination of HNCO via a novel rearrangement

The reactions of ionised acetanilide, C(6)H(5)NH(=O)CH(3)(.+), and its enol, C(6)H(5)NH(OH)=CH(2)(.+), have been studied by a combination of tandem mass spectrometric and computational methods. These two isomeric radical cations have distinct chemistries at low internal energies. The keto tautomer eliminates exclusively CH(2)=C=O to give ionised aniline. In contrast, the enol tautomer loses H-N=C=O, via an unusual skeletal rearrangement, to form predominantly ionised methylene cyclohexadiene. Hydrogen atom loss also occurs from the enol tautomer, with the formation of protonated oxindole. The mechanisms for H-N=C=O and hydrogen atom loss both involve cyclisation; the former proceeds via a spiro transition state formed by attachment of the methylene group to the ipso position, whereas the latter entails the formation of a five-membered ring by attachment to the ortho position. The behaviour of labelled analogues reveals that these two processes have different site selectivities. Hydrogen atom loss involves a reverse critical energy and is subject to an isotope effect. Surprisingly, attempts to promote the enolisation of ionised acetanilide by proton-transport catalysis were unsuccessful. In a reversal of the usual situation for ionised carbonyl compounds, ionised acetanilide is actually more stable than its enol tautomer. The enol tautomer was resistant to proton-transport catalysed ketonisation to ionised acetanilide, possibly because the favoured geometry of the encounter complex with the base molecule is inappropriate for facilitating tautomerisation.     

The structure and mechanism of formation of C5H9O+ from ionized phytyl methyl ether

The recent proposal that ionized phytyl methyl ether [C₁₆H₃₃(CH₃)C=CHCH₂OCH ₃ ^+· ] undergoes an allylic rearrangement to ionized isophytyl methyl ether [CH₂=CHC(C₁₆H₃₃)(CH₃)OCH ₃ ^+· ] before elimination of an alkyl radical is discussed. Both literature precedent and new results in which the structure of the [M-C₁₆H ₃₃ ^· ]⁺ fragment ion is established by comparison of its collision-induced dissociation mass spectrum with the spectra of isomeric C₅H₉O⁺ ions of known structure are inconsistent with this proposal. The forma Hon of CH₃CH=CHCH=O⁺CH₃ by loss of a γ-alkyl substituent without skeletal isomerization rather than CH₂=CHC(CH₃)=O⁺CH₃ after allylic rearrangement is explained in terms of a mechanism that involves two 1,2-H shifts, followed by σ-cleavage of the resultant ionized enol ether, C₁₆H₃₃(CH₃)CH-CH=CHOCH ₃ ^+· .     

Reactions of fluoroalkanesulfonyl azides with vinyl ether and tetrakis(dimethylamino)ethylene

The reactions of fluoroalkanesulfonyl azides 1 with some electron-rich olefins have been studied. Alkyl vinyl ethers reacted with 1 readily at 0 °C or room temperature (RT) and did not give the corresponding N-fluoroalkanesulfonyl azilidines but 1-fluoroalkanesulfonyl-1,2,3-triazolines 3, which decomposed slowly at room temperature to form 1,4-fluoroalkanesulfonyl-2,5-alkoxyl-piperazines 4 with elimination of nitrogen gas. In contrast, more electron-rich alkene, tetrakis(dimethylamino)ethylene (TDAE) reacted with 1 affording N-fluoroalkanesulfonyl bis(dimethylamino)amidines 6 accompanying the release of N₂. Reaction mechanisms are discussed.     

Surface tensions,densities and refractive indexes of mixtures of dibutyl ether and 1-alkanol at T=298.15 K

The aim of our present work is to present measurements of the surface tension, density and refractive index for binary mixtures of dibutyl ether with eight 1-alcohols {C₄H₉OC₄H₉+C₃H₇OH,+C₄H₉OH,+C₅H₁₁OH,+C₆H₁₃OH,+C₇H₁₅OH,+C₈H₁₇OH,+C₉H₁₉OH and +C₁₀H₂₁OH} at the temperature of 298.15 K and atmospheric pressure. The experimental data are correlated by means of suitable empirical expressions, which relate the surface tension and refractive index of a mixture with its corresponding density. Also, calculated are the surface tension deviations and excess molar volumes from the measured data for all binary mixtures. The results of the study attending to the number of carbon atoms of the 1-alcohol are discussed.