106-95-6Relevant articles and documents
Kinetics of free radicals produced by infrared multiphoton-induced decompositions. 1. Reactions of allyl radicals with nitrogen dioxide and bromine
Slagle, Irene R.,Yamada, Fumiaki,Gutman, David
, p. 149 - 153 (1981)
A new versatile technique to study quantitatively the gaseous reactions of polyatomic free radicals is described in detail. Free radicals are generated homogeneously in a tubular reactor by the infrared multiphoton-induced decomposition (MPD) of suitable radical precursors. The concentrations of reactants and products (both stable and labile) are monitored by using photoionization mass spectrometry. Reactions of the allyl radical, generated by the MPD of allyl bromide, with nitrogen dioxide and bromine have been studied at 300 K. The measured rate constants are 3.9(±0.8) × 10-11 cm3 s-1 for the C3H5 + NO2 reaction and 9.0(±1.8) × 10-12 cm3 s-1 for the C3H5 + Br2 reaction. The potential of the experimental facility for other kinds of studies is discussed.
-
Frazer,Gerrard
, p. 3624,3626, 3627 (1955)
-
Kinetics of the Reactions of Unsaturated Hydrocarbon Free Radicals (Vinyl, Propargyl, and Allyl) with Molecular Bromine
Timonen, R. S.,Seetula, J. A.,Gutman, D.
, p. 8217 - 8221 (1993)
The kinetics of the reactions of three unsaturated free radicals (vinyl, propargyl, and allyl) with molecular bromine have been studied by using a tubular reactor coupled to a photoionization mass spectrometer.The radicals were homogeneously generated by the pulsed photolysis of precursor molecules at 193 nm.The subsequent decays of the radical concentrations were monitored in time-resolved experiments as a function of Br2 concentration to obtain the rate constants of these Br-atom metathesis reactions.Rate constants were measured as a function of temperature to obtain Arrhenius parameters.The following rate constant expressions were obtained (units of the preexponential factor are cm3 molecule-1 s-1 and activation energies are kJ mol-1; the temperature range covered in each study is also indicated): C2H3 + Br2 , C3H3 + Br2 , and C3H5 +/- Br2 .The kinetics of R + Br2 reactions is reviewed, and the factors governing the reactivity of polyatomic free radicals in R + Br2 reactions are discussed.
Generalized route to metal nanoparticles with liquid behavior
Warren, Scott C.,Banholzer, Matthew J.,Slaughter, Liane S.,Giannelis, Emmanuel P.,DiSalvo, Francis J.,Wiesner, Ulrich B.
, p. 12074 - 12075 (2006)
We report the generalized synthesis of metal nanoparticles with liquid-like behavior. We introduce a thiol-containing ionic liquid, N,N-dioctyl-N-(3-mercaptopropyl)-N-methylammonium bromide, which serves as a ligand for platinum, gold, palladium, and rhodium nanoparticles. A rapid reduction using THF-soluble metal salts in the presence of the thiol generates nanoparticles with tunable sizes and size distributions. The as-synthesized nanoparticles are a solid and decompose before melting. Upon exchange of the halide anion for an amphiphilic sulfonate anion, however, the nanoparticles exhibit liquid-like properties at room temperature. The liquids have high metal loadings; for example, the 2.7 nm platinum nanoparticle liquid is 36% platinum by mass. Copyright
Synthesis and characterization of ferroelectric liquid crystalline siloxanes containing 4-hydroxyphenyl(2S,3S)-2-chloro-3-methylvalerate
Lin, Chih-Hung
, p. 33 - 42 (2012)
New series of organosiloxane ferroelectric liquid crystalline materials have been synthesized, and their mesomorphic and physical properties have been characterized. These new series contain bis-siloxane or tris-siloxane unit attached to the flexible alkyl chain end of (2S,3S)-2-chloro-3-methylvalerate. The siloxane molecule induction is helpful to the chiral smectic C (S C) formation and chiral SC* stabilization, and it simultaneously causes the liquid crystal temperature range of chiral S C* to be broader. The siloxane member is helpful in reducing the smectic C (SC) transation shift temperature, and the molecule containing tris-siloxane units shows better effect than the bis-siloxane one. The synthesis and characterization of the new FLCs materials which exhibit SC* phase at room temperature and higher spontaneous polarization are presented.
-
Philippi
, p. 277 (1929)
-
-
Asahara,T. et al.
, p. 1130 - 1133 (1971)
-
Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
Fiorio, Jhonatan L.,Rossi, Liane M.
, p. 312 - 318 (2021/01/29)
The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
Piperazine-promoted gold-catalyzed hydrogenation: The influence of capping ligands
Barbosa, Eduardo C. M.,Camargo, Pedro H. C.,Fiorio, Jhonatan L.,Hashmi, A. Stephen K.,Kikuchi, Danielle K.,Rossi, Liane M.,Rudolph, Matthias
, p. 1996 - 2003 (2020/04/22)
Gold nanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since gold nanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold-ligand interface. Citrate (Citr), poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), and oleylamine (Oley)-stabilized Au NPs were not activated by piperazine for the hydrogenation of alkynes, but the catalytic activity was greatly enhanced after removing the capping ligands from the gold surface by calcination at 400 °C and the subsequent adsorption of piperazine. Therefore, the capping ligand can limit the catalytic activity if not carefully removed, demonstrating the need of a cleaner surface for a ligand-metal cooperative effect in the activation of H2 for selective semihydrogenation of various alkynes under mild reaction conditions.