The geometrical structures of the substituted oxiranes

Conclusions The oxiranecarbaldehydes exist as single conformers in solution. The carbonyl group is rotated out of the plane of the bisector of the oxide ring by some 40°, the carbonyl-group oxygen being thereby separated from the oxide-ring oxygen. This conformation is favored from the standpoint of dipole-dipole interactions.Translated from Izvestiya Akademii Nauk SSSR, Sariya Khimicheskaya, No. 6, pp. 1257–1260, June, 1979.The authors would like to thank V. N. Zinin who prepared the PMR spectra.     

Geometrical structures of the substituted oxiranes. 7. The conformations of the nitrooxiranes

Conclusions The NO₂ groups of trans-2-methyl- and trans-2-trichloromethylnitrooxirane exist in bisector conformations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, Wo, 8, pp. 1761–1763, August, 1979.     

1H NMR spectra of oxiranes. cis-Arylmethyl oxiranes substituted in the phenyl ring

The ¹H NMR parameters for a number of cis-arylmethyl oxiranes are reported and discussed in comparison with those of trans derivatives and styrene oxides substituted in the phenyl ring. While the macroscopic behaviour of the results is in agreement with a perturbative mechanism through the oxirane ring that is mainly electrostatic in character, a small contribution due to conjugative interaction is not excluded. It seems likely that the effect of substituents in the phenyl ring is mainly transmitted through bonds rather than through space, and that the different polarisation of the C? H bonds in the oxirane ring is mainly responsible for the different behaviour of the protons in cis- and trans- arylmethyl oxiranes towards the effect of substituents.     

Rearrangement reactions of the molecular ions of some substituted aliphatic oxiranes

The fragmentation reactions of glycidic methyl ester (1) and of its derivatives (2–6) substituted by one, two and three methyl groups, respectively, at the oxirane ring, of the corresponding glycidols (7–12), and of the glycidyl ethers (13–16) in the 70 eV mass spectra have been studied using isotopic labelling and mass-analysed ion kinetic energy spectrometry. It is shown that the typical reaction of these aliphatic oxirane radical cations carrying a nucleophilic methoxy group and hydroxy group, respectively, at the side chain corresponds under high-energy conditions to a rearrangement by a methoxy group or a hydroxy group migration to the β-carbon atom of the oxirane moiety. This rearrangement is very likely mediated by the isomerization of the molecular ions into distonic ions via C? C bond cleavage within the oxirane ring.     

Synthesis of substituted furans by platinum-catalyzed cyclization of propargylic oxiranes in aqueous media

The reaction of propargylic oxiranes with platinum catalyst in aqueous media is described. Furans having a variety of substituents were conveniently synthesized with high efficiency.     

Palladium-catalyzed alkylation of vinyl oxiranes with substituted allenes. Direct access to bifunctionalized allylic alcohols

The first palladium-catalyzed alkylation of vinyl oxiranes with substituted allenes to form functionalized allylic alcohols is described. The reaction of activated allenes 5 with vinyl oxiranes 1 in the presence of catalytic amounts of Pd(PPh(3))(4) (10 mol %) and 1,3-bis(diphenylphosphino)propane (dppp) (20 mol %) in THF at 60 degrees C gave the corresponding allylic alcohols 6 in good to excellent yields. The allylic alcohols were obtained in different ratios of trans/ cis isomers.     

Sum-over-states calculation of the specific rotations of some substituted oxiranes, chloropropionitrile, ethane, and norbornenone

A sum-over-states approach has been applied to the calculation of the specific rotations of several substituted oxiranes, 2-chloropropionitrile, and 30 degrees-rotated ethane. In each case, the first few excited states proved to have only a relatively small effect on the calculated specific rotation. It was necessary to use a very large number of excited states in order to achieve convergence with the results of the more direct linear response method. However, the latter does not give information on which excited states are important in determining the specific rotation. Norbornenone is unique in that its greatly enhanced specific rotation as compared to norbornanone is associated with the low-energy n-pi* transition. The C=C bond orbitals interact with the C=O in the LUMO, and a density difference plot for going from the ground state to the first excited state clearly shows the perturbation of the C=C.     

Photochemical properties and structures of substituted norbornadienes

The spectral and photochemical properties of 3-phenylnorbornadiene-2-(N-phenyl)aldimine and 3-phenyl-2-(2,2-dicyanovinyl)norbornadiene have been studied, and their structures have been established by X-ray analysis. It was found that the C(2)=C(3) bonds in these compounds are longer than those in unsubstituted norbornadienes. It was established that long-wave absorbtion boundaries and quantum yields of the photoisomerization of 2,3-disubstituted norbornadienes to give the corresponding quadricyclanes increase as the C(2)=C(3) bond length increases and as the bond order decreases.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 504–508, March, 1995.This work was supported by the International Science Foundation (grant No. RNC 000).     

Mass spectra and structures of substituted carbazoles

The anomalous character of the dependence of the stability with respect to electron impact on the size of the alkyl group in alkylacetylcarbazoles leads to the conclusion that the molecular ion undergoes profound rearrangement prior to detachment of the first neutral particle, during which the effect of the functional group on this process is manifested weakly. The functional group is not always the determining factor in the formation of the primary fragment ions, particularly if the processes involving the participation of the alkyl group lead to more stable ions than the processes involving the participation of a labile functional group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 931–937, July, 1977.     

Potentiometric microdetermination of oxiranes

Summary A potentiometric microtitration for the determination of high molecular weight oxiranes is presented. It is based on the reaction of oxiranes with quaternary ammonium bromide and titration with 0.01N perchloric acid. The preferred solvent is acetic acid although small amounts of toluene or chloroform may be used. Epoxy equivalents as high as 370,000 have been determined.

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Potentiometrische Mikrobestimmung von Äthylenoxiden

Zusammenfassung Eine potentiometrische Mikrotitrationsmethode zur Bestimmung hochmolekularer Äthylenoxide wurde vorgeschlagen. Sie beruht auf deren Reaktion mit quaternärem Ammoniumbromid und Titration mit 0,01N Perchlorsäure. Vorzugsweise dient Essigsäure als Lösungsmittel, doch kann man auch kleine Mengen Toluol oder Chloroform verwenden. Epoxyäquivalente bis zu 370 000 wurden bestimmt.

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Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore Laboratory under contract number W-7405-ENG-48.     

Thermal reactions of oxiranes

The pyrolytic reactions of tetramethylethylene oxide, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, 1,2-epoxyethylbenzene, 1,2-epoxy-2-phenylpropane, 1,2-epoxy-1-phenylpropane, and 1,2-epoxy-1,2-diphenylethane were investigated at 600 °C using a conventional pyrolysis flow system. The products are mainly due to thermal cleavage of the oxirane ring followed by rearrangement to give carbonyl compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 946–949, May, 1995.The authors acknowledge the financial support from B. P. International for this project.     

Geometrical structures of the azines of substituted acetophenones

Conclusions By drawing on measured values of dipole moments and Kerr constants and a study of vibrational spectra, it has been shown that the molecules of the symmetrical azines of the acetophenones exist as EE forms of the s-trans conformer, the angle of rotation of the azomethylidyne fragments around the N-N bond being 130±5° with the phenyl rings displaced out of the C=N bond planes by 35±5°.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1996–1999, September, 1977.