Rearrangement with 1,2-migration of chlorine in reaction of p-methylbenzyl radicals with 3,3,3-trichloropropene

Conclusions The reaction of p-xylene with 3,3,3-trichloropropene, initiated by peroxides, leads to the formation of 1,1-dichloro-4-(p-tolyl)-1-butene, 1,1,2-trichloro-4-(p-tolyl)butane, and 1,1-dichloro-2-chloromethyl-3-(p-tolyl)propane, which testifies to a rearrangement of the CCl₃HCH₂CH₂C₆H₄CH₃ radicals to the C1₂CHCI-CH₂ CH₂C₆H₄CH₃ radicals with the 1,2-migration of chlorine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2122–2124, September, 1976.     

Reactions of the radical cations of aliphatic aldehydes in freon matrices

ESR spectra of -irradiated, at –196 °C, solutions of acetic and propionic aldehydes in freon-11 and freon-113 affected by aldehyde concentration, temperature, and the action of light have been studied. It has been shown that the radical cations CH₃CHO⁺ are converted into neutral radicals CH₃O and CH₃HOH and the cations CH₃CH₂CHO⁺. are converted to RO and CH₃HCHO due to ion-molecular reactions of proton transfer /CH₃O and CH₃HCHO/ of hydrogen atom transfer /CH₃HOH/.     

ESR spectroscopic investigation of steric and polar factors in the addition of radicals to unsaturated compounds

The rate constants of the addition of CCl₃CH₂ClCH₃(R⁶) radicals to -methyl-styrene, styrene, methyl methacrylate, methyl acrylate, and acrylonitrile and of CCl₃CH₂(CH₃)₂(R⁷) radicals to styrene, methyl acrylate, and acrylonitrile were determined by ESR spectroscopy. It was shown that the radicals R⁶ and R⁷ possess approximately equal reactivity in addition to unsaturated compounds, despite the difference in the donor-acceptor properties of the substituents at the vinyl group. In a comparison of the reactivity of radicals R⁶ and R⁷ with the reactivity of radicals CCl₃CH₂H₂(R¹), CCl₃CH₂HCH₃(R³), CCl₃CH₂HCl(R⁴), and ClCH₂CH₂Cl₂(R⁵) [1] in addition reactions, it was shown that polar and steric effects of the substituents situated in the -position to the radical site of the above-mentioned radicals, as well as the donor-acceptor properties of the substituents at the vinyl group in the unsaturated compounds, lead to appreciable changes in reactivity.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 136–141, January, 1992.     

A spin-trap ESR study of the decomposition of alkyl formates

Conclusions By using nitroso compound ESR spin traps it has been shown that the alkyl formates break down into radicals under irradiation at 2537 Å and 25°C, and this regardless of whether or not the system contains added tert-butyl peroxide. The mechanism of breakdown varies with the alkyl-formate structure, Under our conditions of irradiation, the product radicals were as follows: OOCH₃ from methyl formate; OOCH₂CH₃ and HCOOHCH₃ from ethyl formate; OOC(CH₃)₃ and (CH₃)₃ from tert-butyl formate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 542–545, March, 1977.     

A spin-trap ESR study of the regrouping of radicals with 1,3 or 1,5 hydrogen migration

Conclusions Spin-trap (2-methyl-2-nitrosopropane) ESR methods have been used to demonstrate the formation of R¹O₂CR²CH₂CH₂C₆H₁₃ (R¹=H, CH₃ and R²=Cl, CH₃) radicals during the photoinitiated reaction ( 2537 Å) of 1-octene with BrCHClCOOH and CH₃CHBrCOOCH₃ in the presence of tert-outyl peroxide and (C₃H₅)₃SiH. Formation of these radicals indicates regrouping of the R¹O₂CCHR²CH₂HC₆H₁₃ radical with 1,3 H atom migraion and, possibly, regrouping of the R¹O₂CCHR²CH₂CH(C₆H₁₃)CH₂CHC₆H₁₃ radical with 1,5 H atom migration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 545–549, March, 1977.     

Structure du radical cyano-vinyle CH2=Ċ-CN Etude expérimentale et théorique

Résumé Tout d'abord, on montre par RPE que le radical CH₂=-CN possède à basse température une structure instable pliée et à température plus élevée une structure stable linéaire. Un calcul théorique sur ce radical ainsi que sur le radical butatriényle est en bon accord avec les résultats expérimentaux.

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The structure of the Cyano-Vinyl Radical CH₂=-CN experimental and theoretical study

First, it is shown by ESR that the radical CH₂=-CN at low temperature presents an unstable bent structure and at higher temperature a stable linear structure. A theoretical calculation on this radical and on the butatrienyl one is in good agreement with the experimental results.

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Zusammenfassung Aus ESR Messungen wird gefolgert, daß das Radikal CH₂=-CN bei tiefer Temperatur in einer instabilen gebogenen Struktur und bei höherer Temperatur in einer stabilen linearen Struktur vorliegt. Theoretische Berechnungen stehen sowohl für dieses als auch für das Butatrienyl-Radikal in guter Übereinstimmung mit experimentellen Daten.

     

Investigation of the structure and reactivity of the stable perfluorodiisopropylethylmethyl radical by ESR and molecular mechanics

The hyperfine coupling (HFC) constants of the unpaired electron with the fluorine nuclei in the stable radical [(CF₃)₂CF]₂CF₂CF₃ (II) were determined by ESR. The stable conformation and the barriers to rotation of the substituents in this radical were calculated by molecular mechanics. The results were consistent with the ESR data. The kinetics of the destruction of the radical (II) were investigated, and the kinetic parameters of the dissociation were determined (k₁₄₀=4.6·10^–4 sec^–1, E_act=30±5 kcal/mole). The disappearance of the radical (II) is accompanied by the accumulation of the new radical (CF₃)₂CF(CF₃)CF(CF₃)CF₂CF₃ (IV), which was studied by ESR. Heating of (II) in the presence of electron donors leads to the partly reversible reduction of the radical (II).Translated from Izvestiva Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1507–1512, July, 1991.     

A new stable perfluoroalkyl radical

Conclusions The radiolysis of perfluoro-4-methyl-2-pentene gives a stable radical whose ESR spectrum corresponds to (CF₃)₂CFFCF(CF₃)₂.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1667–1669, July, 1985.The authors express their gratitude to Yu. L. Bakhmutov for assistance in this work.     

Relative telomerization rate of trimethylvinylsilane with methyl propionate

Conclusions The telomerization of trimethylvinylsilane with methyl propionate is accompanied by a rearrangement of the Me₃SiHCH₂CH(Me)CO₂Me radicals and a 1,3-migration of hydrogen.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1425–1426, June, 1984.     

Transformations of Dichloromethane Radicals in Alkaline Water Solutions

Among transformation products of HCl₂ and H₂Cl radicals generated by -irradiation of deaerated water solutions of dichloromethane oxygen-containing compounds (formic acid, formaldehyde, carbon monoxide) and chloride ions were found. The radicals CHCl₂ suffer nucleophilic substitution by hydroxyl ions affording anion-radicals HCOO^{- 2} that further transform into formic acid. At the growing concentration of alkali the frequency of chlorine substitution with hydroxyl ions in the dichloromethane radicals increases, and their transformation process becomes a chain reaction.     

Reaction of 3,3,3-trifluoropropene-1 with bromoform and methylene bromide

The radical telomerization of 3,3,3-trifluoropropene with bromoform and methylens bromide has been studied. The nature of the products with bromoform depends substantially on the method of initiation. In the presence of Fe(CO)₅ + DMF, telomers of CHBr₂(CH₅₂CHCF₃)_nBr are formed, while with initiation with benzoyl peroxide other compounds are also formed that contain two, three, or four bromine atoms per molecule. To elucidate the formation of these products a reaction scheme is proposed that involves rearrangement of CHBr₂CH₂CH(CF₃)CH₃CHCF₃ radicals to CBr₂CH₂CH(CF₃)CH₂CH₂CF₃ radicals.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2558–2562, November, 1989.     

Radical reactions of ethyl orthoformate with 3,3,3-trifluoropropene

Conclusions The radical reaction of 3,3,3-trifluoropropene with ethyl orthoformate largely leads to the formation of the adduct, EtOC(O)OCH(Me)CH₂CH₂CF₃ due to rearrangement of the intermediate radicals with 1,5 hydrogen atom migration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp.1418–1420, June, 1985.     

Radical reaction of ethyl orthoacetate with 3,3,3-trifluoropropene

Summary The reaction of 3,3,3-trifluoropropene with ethyl orthoacetate leads to the formation of an acetate CH₃C(O)OCH(CH₃)CH₂CH₂CF₃ and a ketone CH₃C(O)CH₂CH(CF₃)CH₂CH₂CF₃. A reaction mechanism is proposed which involves rearrangement of the radicals CR₃C(OC₂H₅)₂OCH(CH₃) (CH₂CHCF₃) _n ^. with 1,7- and 1,5-migration of an H atom and stabilization by fragmentation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1583–1586, July, 1986.     

EPR study of the rearrangement of (C2H5)3SiCH2CH2ĊCl2 radicals

Conclusions It has been established that the rearrangement of (C₂H₅)₃Si(CH₂)₂Cl₂ radicals into (C₂H₅)₂Si(CH₃CH)(CH₂)₂CCl₂H takes place by an intramolecular mechanism with 1,5-migration of a hydrogen atom. The rate constant for the isomerization has been determined at 20°C and found to be (2.2 ± 0.3)·10³ sec^–1.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2512–2516, November, 1988.     

Alkylation of perfluoro-2-methyl-2-pentylcarbanion with alkyl and allyl halides

Perfluoro-2-methyl-2-pentylcarbanion, generated from perfluoro-4-methyl-2-pentene in an aprotic solvent, reacted with halides RX, where R = alkyl or allyl and X = I, Br, or Cl, to give fluorohydrocarbons of the general formula CF₃CF₂CF₂C(CF₃)₂R. No reaction with iso-propyl iodide and with 1-iodo-2,2,2,-trifluoroethane occurred. The reaction with 1-iodo-3,3,3,-trifluoropropene resulted in the formation of 3,3,3,-trifluoropropene and 2-H-perfluoro-2-methyl-pentane.     

New aromatic pentafluoro-λ-sulfanyl (SF5) derivatives, m-SF5(CF2)2C6H4X: (X = N3, Br, OC(O)CHCH2, CHCH2)

Preparation of the following new m-SF₅CF₂CF₂C₆H₄X derivatives has been achieved: X=N₃(2), Br(3), OC(O)CHCH₂(4), CHCH₂(5). The compounds were characterized by their respective IR, NMR, mass spectra (MS) and high resolution mass spectrometry (HRMS). An improved yield of SF₅(CF₂)₂C₆H₅ (1) is also reported along with the synthesis of the polyacrylate (6) and polystyrene (7) from their respective monomers.     

Electron-impact studies of organometallic molecules—VII. Some transition metal complexes derived from 3,3,3-trifluoroprop-1-yne

The mass spectra of ten complexes derived from 3,3,3-trifluoroprop-1-yne, namely (CF₃C?CH)CO₂(CO)₆, (CF₃C?CH) [π? C₅H₅Ni]₂, (CF₃C?CH)₃Co₂(CO)₄, CF₃CH₂C[Co(CO)₃]₃, are discussed in terms of their structures. The major processes observed can be satisfactorily explained in terms of (i) loss of carbonyl groups, if present; (ii) loss of one fluorine atom from the parention (iii) elimination of neutral metal fluorides, with ligand transfer reactions in the case of the iron complexes; (iv) elimination of neutral fluorocarbon molecules.     

A Nonempirical Quantum-Chemical Study and Natural Bond Orbital Analysis of C6H5XCY3 Species (X = SO or SO2, Y = H or F)

The potential functions of internal rotation about the C² _sp—S bonds for C₆H₅XCY₃ species (X = SO or SO₂, Y = H or F) have been obtained at the MP2 (full)/6-31+G(d) level of ab initio theory. It is found that the spatial structures with the plane of C² _sp—S—C³ _sp bonds, which is near perpendicular to the benzene ring plane, are the energy-favourable conformations. The values of the rotational barrier about the C² _sp—S bond are equal to (kJ/mole): 21.2 (C₆H₅SOCH₃), 29.0 (C₆H₅SOCF₃), 20.4 (C₆H₅SO₂CH₃), and 28.2 (C₆H₅SO₂CF₃). On the basis of the Natural Bond Orbital (NBO) analysis results, it has been revealed that the double S=O bond is a strongly polarized covalent -bond, whereas -bond electrons practically are localized on the oxygen atom. The S=O bond order for aromatic sulfoxides and sulphones is mainly caused by hyperconjugational interactions according to the LP(O) ^*(S—C_ipso) and LP(O) ^*(S—C _Y ) mechanisms. In sulphones there is also the additional mechanism of hyperconjugational interactions such as LP(O^{1 *}(S—O²) and LP(O²) ^*(S—O¹). With the replacement of one hydrogen atom on the —XCY₃ group, the charge loss of the unsubstituted benzene molecule increases: —SOCH₃ < —SO₂CH₃ < — SOCF₃ < —SO₂CF₃. The substitution of the —CH₃ group for the —CF₃ group weakly influences the charge value on the sulfur atom but effects the acceptor characteristics of the substituent to a greater extent than the variation of the sulfur atom coordination.     

Atranes. II. Dipole moments and structure of silatranes

Possible steric configurations of 1-organyl- and 1-organoxysilatranes,, are considered. The dipole moments of six compounds of this type (X=CH₃, (CH₃)₂CH, CH₂=CH, C₆H₅, C₂H₅O, C₆H₅O) have been found experimentally to be extremely high, 5.3–7.1 D. They conclusively show that the silatranes contain a semipolar transannular coordinate bond SiN between the negatively charged 5 -covalent silicon atom in the middle of the planar SiO₃ group and the tetrahederal onium nitrogen atom.Part I, see [1].