1605-73-8Relevant academic research and scientific papers
Studies of Free Radicals at High Pressures. 2. Kinetics for a Variety of Reactions
Marriott, P. R.,Griller, D.
, p. 1521 - 1525 (1981)
Kinetic EPR studies of a variety of free-radical reactions have been carried out at high pressures.Volumes of activation were measured for the β-scission reactions of di-tert-butyliminyl (3.0 +/- 1.0 cm3 mol-1) and triethoxy-tert-butoxyphosphoranyl (0.2 +/- 1.9 cm3 mol -1), for self-reaction of di-tert-butyliminyl (-18.0 +/- 5.3 cm3 mol-1), and for the rearrangements of 2,4,6-tri-tert-butylphenyl (5.3 +/- 1.7 cm3 mol -1) and 2,4,6-tris(perdeuterio-tert-butyl)phenyl (-1.2 +/- 2.0 cm3 mol-1).These measurements improve the descriptions of the transition states for the variuos reactions and in the case of the phenyl rearrangements provide supporting evidence for a mechanism involving quantum mechanical tunnelling.
Mass spectrometric study of the thermal decomposition mechanism of vapors of 2,2,6,6-tetramethyl-3-iminoheptane-5-one and its copper(II) complex
Turgambaeva, Assia E.,Krisyuk, Vladislav V.,Stabnikov, Pavel A.,Igumenov, Igor K.
, p. 5001 - 5006 (2007)
Thermal conversions of vapors of ketoimine C(CH3)3C(NH)CH2C(O)C(CH3)3 (Htmha = 2,2,6,6-tetramethyl-3-iminoheptane-5-one) and its chelate coordination compound with copper Cu(tmha)2 is studied by in situ mass spectrometry in a vacuum and in the presence of hydrogen. Experiments are carried out under conditions close to low pressure chemical vapor deposition at the evaporator temperature of 130 °C and the reactor temperature range 130-500 °C. It is found that compounds are monomeric in the gas phase. Based on temperature dependences of the composition of primary gaseous products, the mechanism of thermal decomposition is proposed. The decomposition of ketoimine on the heated surface begins at 350 ± 10 °C and proceeds by the elimination of terminal groups. Its copper complex decomposes in two directions and yields both molecular and radical products. The latter provide the assumption that metallic copper forms as the only one solid product. The results obtained are compared with those for copper dipivaloylmethanate(2,2,6,6-tetramethylheptane-3,5-dionate).
Laser Flash Photolysis-Electron Spin Resonance Kinetic Studies of Homolytic Reactions in Solution
Baban, Jehan A.,Goddard, Jeffrey P.,Roberts, Brian P.
, p. 1269 - 1274 (1986)
Laser flash photolytic (308 nm) generation coupled with time-resolved e.s.r. spectroscopic detection of radical intermediates has been used to obtained absolute rate coefficients and activation parameters for a number of uni- and bi-molecular homolytic reactions in solution.The results accord well with ButOCO -> But + CO2 (a) (EtO)3POBut -> But + (EtO)3PO (B) ButO + cyclo-C5H10 -> cyclo-C5H9 + ButOH (C) ButO + ButOMe -> ButOCH2 + ButOH (D) Me3SiO + cyclo-C5H10 -> cyclo-C5H9 + Me3SiOH (E) Me3SiO + ButOMe -> ButOCH2 + Me3SiOH (F) those obtained previously for some of these reactions using other techniques.The data for reaction (C) are in excellent agreement with those obtained by laser flash photolysis coupled with optical detection of transients, but differ markedly from results obtained previously by a flash photolysis/e.s.r. technique.The kinetic results for the hydrogen transfers (E) and (F) represent the first absolute rate data for reactions of trialkylsiloxyl radicals.The trimethylsiloxyl radical is more reactive in hydrogen abstraction and also more electrophilic than ButO; these differences are attributable to the ?-acceptor properties of the Me3Si group.
Kinetic EPR studies of the decay of tert-butyl alkoxy, silyloxy, germyloxy, and stannyloxy nitroxides
Lucarini, Marco,Pedulli, Gian Franco,Alberti, Angelo,Benaglia, Massimo
, p. 9603 - 9607 (1992)
The kinetics of decomposition of oxynitroxides Me3CN(O.)OMR3, with R3M = Me3C, Bu3Sn, Ph3Ge, and Ph3Si, has been studied by EPR at different temperatures, and the activation parameters have been determined. While the first nitroxide undergoes cleavage at the nitrogen-oxygen bond more readily than at the nitrogen-carbon bond, the organometallic nitroxides essentially fragment with elimination of a tert-butyl radical with rates of fragmentation increasing, at ordinary temperatures, along the sequence Ph3Ge 3Si 3Sn. A very large reduction of the frequency factor for the decomposition was observed on descending the periodic table. This has been explained in terms of an equilibrium between the nitroxide adduct and its dimer; experimental evidence supporting the existence of this equilibrium has been obtained.
Time-Resolved REMPI Detection of Methyl Radicals Generated in Laser-Induced Unimolecular Reactions
Froechtenicht, Ralf,Hartmann, Matthias
, p. 16290 - 16295 (1995)
The specific rate constants for the photofragmentation of four substituted benzene molecules (ethylbenzene, tert-butylbenzene, toluene, benotrifluoride) following pulsed laser excitation at λ=193 nm were measured in a molecular beam experiment by monitoring the change of the intensity of the nascent products as a function of time delay between excitation and detection laser pulses.In the case of toluene (C6H5CH3), ethylbenzene (C6H5CH2CH3), and tert-butylbenzene (C6H5C(CH3)3) a (3+1)REMPI process a Λ=450.8 nm was used to ionize the CH3 products, which were detected in a time-of-flight mass spectrometer.Following dissociation of benzotrifluoride (C6H5CF3) the trifluormethyl radical CF3 was detected at λ=455 nm.The measured specific rate constants can be modeled satisfactorily by using the SACM (statistic adiabatic channel model) statistical theory.
BTK INHIBITOR RING DERIVATIVE, PREPARATION METHOD THEREFOR AND PHARMACEUTICAL APPLICATION THEREOF
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, (2022/04/09)
A BTK inhibitor ring derivative, a preparation method therefor and a pharmaceutical application thereof. The BTK inhibitor ring derivative is a compound represented by a general formula (I) or a stereoisomer, a solvate, a prodrug, a metabolite, a pharmaceutically acceptable salt or co-crystal thereof, and the BTK inhibitor ring derivative is used to treat BTK-related diseases such as tumors or autoimmune system diseases.
Thermolysis of 3,3,5,5-tetramethyl-1,2,4-trithiolane 1-oxide: First matrix isolation of the HOSS· radical
Reisenauer, Hans Peter,Mloston, Grzegorz,Romanski, Jaroslaw,Schreiner, Peter R.
scheme or table, p. 3408 - 3415 (2012/09/11)
Flash vacuum pyrolysis of 3,3,5,5-tetramethyl-1,2,4-trithiolane 1-oxide performed at 700 °C yields the 1-oxatrisulfan-3-yl radical (HOSS ·) along with disulfur monoxide (S2O) and diisopropyl sulfide, which were isolated in argon matrices at 10 K. Upon irradiation with UV light, the 1-oxatrisulfan-3-yl radical undergoes isomerization to the 1-oxatrisulfan-1-yl radical (HSSO·). Both radicals were identified by comparison of their computed and experimental IR and UV/Vis spectra. In addition, density functional theory (DFT) computations offer a plausible explanation of the most likely reaction mechanism, suggesting that the initial step is a 1,3-H shift with simultaneous ring opening. A 1-oxatrisulfane derivative formed thereby undergoes fragmentations via a radical and a competitive concerted pathway leading to the observed final products. The same mechanism also governs the thermal fragmentation of di-tert-butyl disulfide S-oxide. Its pyrolysis at 700 °C affords an analogous set of products, including the 1-oxatrisulfan-3-yl radical (HOSS·) as the key intermediate. 3,3,5,5-Tetramethyl-1,2,4-trithiolane 1-oxide was pyrolyzed in vacuo (FVP) yielding the 1-oxotrisulfan-1-yl radical, which was isolated in an Ar matrix at 10 K and subsequently characterized by spectroscopic methods (IR and UV/Vis). The same radical was obtained after vacuum pyrolysis of di-tert-butyl disulfide S-oxide.
The role of structural effects on the reactions of alkoxyl radicals with trialkyl and triaryl phosphites. A time-resolved kinetic study
Bietti, Massimo,Calcagni, Alessandra,Salamone, Michela
scheme or table, p. 4514 - 4520 (2010/10/02)
(Figure presented) A time-resolved kinetic study on the reactions of alkoxyl radicals with trialkyl and triaryl phosphites ((RO)3P: R = Me, Et, i-Pr, t-Bu; (ArO)3P: Ar = C6H5, 2,4-(t-Bu)2C6H3) has been carried out. In the (RO)3P series, the alkoxyl radicals (cumyloxyl (CumO ·) and benzyloxyl (BnO·)) undergo addition to the phosphorus center with formation of intermediate tetraalkoxyphosphoranyl radicals (R′OP·(OR)3: R = Me, Et, i-Pr, t-Bu; R′ = Bn, Cum). The addition rate constants are influenced by steric effects, decreasing on going from R = Me to R = t-Bu and from BnO · to CumO·. Rate constants for β-scission of the phosphoranyl radicals R′OP·(OR) 3 have also been determined, increasing, for a given alkyl group R, in the order R′ = tert-butyl · reacts with triaryl phosphites (ArO) 3P to give phenoxyl radicals, with rate constants that are influenced to a limited extent by substitution of the aromatic rings. The radical scavenging ability of these substrates is briefly discussed.
Tin-free radical alkoxyamine addition and isomerization reactions by using the persistent radical effect: Variation of the alkoxyamine structure
Molawi, Kian,Schulte, Tobias,Siegenthaler, Kai Oliver,Wetter, Christian,Studer, Armido
, p. 2335 - 2350 (2007/10/03)
Various C-centered radicals can efficiently be generated through thermal C-O-bond homolysis of alkoxyamines. This method is used to perform environmentally benign radical cyclization and intermolecular addition reactions. These alkoxyamine isomerizations and intermolecular carboaminoxylations are mediated by the persistent radical effect (PRE). In the paper, the effect of the variation of the alkoxyamine structure - in particular steric effects in the nitroxide moiety - on the outcome of the PRE mediated radical reactions will be discussed. Fourteen different nitroxides were used in the studies. It will be shown that reaction times can be shortened about 100 times upon careful tuning of the alkoxyamine structure. Activation energies for the C-O-bond homolysis of the various alkoxyamines are provided. The kinetic data are used to explain the reaction outcome of the PRE-mediated processes.
Homolytic dissociation of 1-substituted cyclohexa-2,5-diene-1-carboxylic acids: An EPR spectroscopic study of chain propagation
Jackson, Leon V.,Walton, John C.
, p. 1758 - 1764 (2007/10/03)
Hydrogen abstraction from 1-substituted cyclohexa-2,5-diene-1-carboxylic acids containing linear, branched and cyclic alkyl substituents, as well as allyl, propargyl (prop-2-ynyl), cyanomethyl and benzyl substituents, has been studied by EPR spectroscopy. For each carboxylic acid, EPR spectra of the corresponding cyclohexadienyl radicals were observed at lower temperatures, followed by spectra due to ejected carbon-centred radicals at higher temperatures. Rate constants, for release of the carbon-centred radicals from the cyclohexadienyl radicals, were determined from radical concentration measurements for the above range of substituents. The rate of cyclohexadienyl radical dissociation increased with branching in the 1-alkyl substituent and with electron delocalisation in the ejected carbon-centred radical; 3,5-and 2,6-dimethyl-substitution of the cyclohexadienyl ring led to reductions in the dissociation rate constants. Rate data for abstraction of bisallylic hydrogens from the cyclohexadienyl acids were also obtained for ethyl, n-propyl and isopropyl radicals. These results indicated a sharp drop in the rate of hydrogen abstraction as the degree of branching in the attacking radical increased. Small decreases in the hydrogen abstraction rate constants were observed for cyclohexadienes containing CO2R substituents.
