Free-radical addition of BrCCl3 to 1-decene initiated by tetrahydrofurane

Khrasch addition of BrCCl₃ to 1-decene and spin-trappinq ESR observations show that BrCCl₃ is spontaneously reduced in THF.     

Charge transfer complexes as possible intermediates in free radical addition and telomerization reactions initiated by metal carbonyl systems

Spectral data were obtained for the charge transfer complexes formed by CBr₄ with Mn₂(CO)₁₀, Fe(CO)₅, and M(CO)₆ (M=Cr, Mo, and W) in the Fe(CO)₅ -DMF system. A qualitative correlation was found between the position and intensity of the charge transfer band and the efficiency of these systems as initiators of homolytic addition and telomerization reactions, proceeding with dissociation of a C- Br bond in the telogen.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 454–458, February, 1990.     

Free-radical copolymerization of styrene with N-phenyl maleimide initiated by thiol

2-Methyl–2-undecanethiol was found efficient to initiate the free-radical copolymerization of styrene (St) with N-phenyl maleimide (NPMI) at 40°C. The initial copolymerization rate increases with the increasing of thiol concentration at first, then keeps constant with the further increasing of the thiol concentration. The charge-transfer complex (CTC) formed between St and NPMI was investigated in different solvents by using ¹H-NMR. There is no definite correlation between CTC equilibrium constant, K, and the polarity of the solvent. With the increasing of CTC concentration, both the copolymerization rate and NPMI content in copolymer enhances, indicating the participation of CTC in both initiation and propagation. The monomer reactivity ratios were calculated to be r_NPMI = 0.052 and r_St ? 0.166, showing an alternating tendency for the copolymerization of St with NPMI. The molecular weight approach has shown again the effect of CTC. The function of thiol as a regulator is mitigated due to the involvement of CTC. © 1992 John Wiley & Sons, Inc.     

Fluorine insertion reactions into pre-formed metal oxides

Fluorine insertion reactions have been shown to be capable of modifying the physical properties of metal oxide materials, as a result of the structural and electronic consequences of fluorine insertion. This has been applied to copper oxide systems and has led to an enhanced understanding of the requirements for superconductivity, and more recently to other magnetic metal oxide systems where it has been shown to tune the magnetic properties of these materials. This review focuses on some important aspects of research on low temperature fluorine insertion reactions into pre-formed metal oxides, since 1998, and reports some new results.     

Free-radical polymerizations initiated by triethylaluminum–cuprous chloride mixtures

Methyl methacrylate was polymerized by triethylaluminum—cuprous chloride catalyst. A study of the polymerization kinetics indicated that the overall rate was represented by the equation, R_p = K[AlEt₃] [CuCl]^½ [M]². The overall activation energy was 16.5 kcal/mole. From ESR measurement and the results of copolymerization of methyl methacrylate with styrene, it was suggested that the catalytic system has the character of a radical initiator. A polymerization scheme was also proposed.     

Free-radical addition to the phosphoryl group

Russian Chemical Bulletin -     

Free-radical polymerization of monomer-polymer solutions initiated by a peroxide-tertiary aromatic amine system

The free-radical polymerization of styrene and methyl methacrylate initiated by the peroxide-tertiary aromatic amine system in the presence of dissolved aromatic polyethers and fluoroelastomer has been studied with the use of quantitative chemical, thermometric, and gravimetric analyses. It has been shown that the rate of polymerization of monomer-polymer solutions is higher than that of pure monomers. The influence of the content of dissolved polymers on the conversion of monomers corresponding to the onset of the gel effect has been estimated. In the presence of the polymer being added, this phenomenon manifests itself at a lower fractional conversion of the monomer. The greater the content of the polymer and the higher the viscosity of the reaction system, the sooner the rise in the rate of polymerization. The experimental evidence of this study makes it possible to control the synthesis of composite materials from monomer-polymer systems.     

Free-radical hydroxylation reactions of alkylboronates

The radical hydroxylation of B-alkylcatecholboranes, easily prepared by hydroboration of olefins, has been investigated. When molecular oxygen was used as oxidizing agent, the corresponding alcohols were obtained directly without alkaline treatment. The presence of Lewis base additives such as Et3N or DABCO has a benefic effect on the selectivity and yield. Alternatively, 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) reacts cleanly with B-alkylcatecholboranes to afford alkyl radicals that can be trapped by a second equivalent of TEMPO to give alkoxyamines. Reduction of the alkoxyamines with zinc in acetic acid affords the desired alcohols. The whole procedure is particularly mild and does not require any basic condition. The two approaches presented in this paper are valuable and represent mild alternatives to the classical alkaline oxidation of organoboranes to alcohols.     

The catalytic effects of metal oxides on thermal decomposition reactions,III

The catalytic activity of a series of iron oxides on the thermal decomposition of potassium chlorate was investigated by methods of thermal analysis. Structural and electronic defects were introduced into the oxide by doping, heat treatment in different atmospheres, and irradiation with-rays. These induced defects changed in a systematic way the conductive properties of the iron oxides and correspondingly, their catalytic activity. The results are consistent with ann-type semiconductive behavior of the oxides.

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Zusammenfassung Die katalytische Aktivität einer Reihe von Eisenoxiden gegenüber der thermischen Zersetzung von Kaliumchlorat wurde durch Methoden der Thermoanalyse untersucht. Strukturelle und elektronische Defekte wurden in das Oxid durch Dosierung, Wärmebehandlung in verschiedenen Atmosphären und Bestrahlung mit-Strahlen eingebaut. Diese induzierten Defekte änderten systematisch die Leitfähigkeitseigenschaften der Eisenoxide und dementsprechend ihre katalytische Aktivität. Die Ergebnisse stimmen mit dem Halbleiterverhalten desn-Typs der Oxide gut überein.

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. , . , , . , n-.

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This work was supported by the U.S. Army Edgewood Arsenal under Project No. DA-18-035-AMC-341(A). The authors are grateful to Mr. B. Zeffert and Mr. Harry A. Brown for valuable discussions and useful suggestions.

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The authors also wish to acknowledge Brent Boldt for the laboratory work which he conducted on this program.     

Free-radical addition of alkanals to acrolein diacetate

Conclusions The free-radical addition of alkanals to acrolein diacetate constitutes an efficient one-step method for the synthesis of 1,1-diacetoxyalkan-4-ones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2813–2815, December, 1988.     

Free-radical addition of alkanethiols to 1-vinylpyrroles

In the presence of 2,2-azobisisobutyronitrile or in the absence of an initiator alkanethiols add to 1-vinylpyrroles exclusively counter to Markovnikov's rule to give 1-(2-alkylthioethyl)pyrroles (in yields up to 94%).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1636–1639, December, 1977.     

Free-radical chain decomposition of ozone initiated by di(tert-butyl) trioxide

Di(tert-butyl) trioxide in a solution of CFCl₃ (Freon-11) at –23 °C exists in equilibrium with the tert-butoxyl and tert-butylperoxyl radicals virtually without irreversible decomposition. The above radicals decompose ozone to dioxygen with a high effective rate constant, which is proprotional to the square root of the Bu^tOOOBu^t concentration. The kinetic scheme describing the found relationships was proposed.     

Hydroamination and hydroalkoxylation catalyzed by triflic acid. Parallels to reactions initiated with metal triflates

Intermolecular additions of the O-H bonds of phenols and alcohols and the N-H bonds of sulfonamides and benzamide to olefins catalyzed by 1 mol % of triflic acid and studies to define the relationship between these reactions and those catalyzed by metal triflates are reported. Cyclization of an alcohol containing pendant monosubstituted and trisubstituted olefins catalyzed by either triflic acid or metal triflates form products from addition to the more substituted olefin, and additions of tosylamide catalyzed by triflic acid or metal triflates form indistinguishable ratios of the two N-alkyl sulfonamides.