542-18-7Relevant articles and documents
Russell,Bridger
, p. 737 (1963)
MULTILE SUBSTITUTIONS IN RADICAL-CHAIN CHLORINATIONS. A NEW CAGE EFFECT
Skell, P. S.,Baxter, H. N.
, p. 2823 - 2824 (1985)
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Sharefkin,Banks
, p. 4313 (1965)
Di-tert-butyl Peroxide: Can Its Photolysis Be Quenched by Carbon Tetrachloride and Why Is It Stable at Room Temperature ?
Davis, S. A.,Gilbert, B. C.,Griller, D.,Nazran, A. S.
, p. 3415 - 3416 (1984)
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Jensen,Bushweller
, p. 3223 (1969)
Non-Heme-Iron-Mediated Selective Halogenation of Unactivated Carbon?Hydrogen Bonds
Bleher, Katharina,Comba, Peter,Faltermeier, Dieter,Gupta, Ashutosh,Kerscher, Marion,Krieg, Saskia,Martin, Bodo,Velmurugan, Gunasekaran,Yang, Shuyi
supporting information, (2021/12/09)
Oxidation of the iron(II) precursor [(L1)FeIICl2], where L1 is a tetradentate bispidine, with soluble iodosylbenzene (sPhIO) leads to the extremely reactive ferryl oxidant [(L1)(Cl)FeIV=O]+ with a cis disposition of the chlorido and oxido coligands, as observed in non-heme halogenase enzymes. Experimental data indicate that, with cyclohexane as substrate, there is selective formation of chlorocyclohexane, the halogenation being initiated by C?H abstraction and the result of a rebound of the ensuing radical to an iron-bound Cl?. The time-resolved formation of the halogenation product indicates that this primarily results from sPhIO oxidation of an initially formed oxido-bridged diiron(III) resting state. The high yield of up to >70 % (stoichiometric reaction) as well as the differing reactivities of free Fe2+ and Fe3+ in comparison with [(L1)FeIICl2] indicate a high complex stability of the bispidine-iron complexes. DFT analysis shows that, due to a large driving force and small triplet-quintet gap, [(L1)(Cl)FeIV=O]+ is the most reactive small-molecule halogenase model, that the FeIII/radical rebound intermediate has a relatively long lifetime (as supported by experimentally observed cage escape), and that this intermediate has, as observed experimentally, a lower energy barrier to the halogenation than the hydroxylation product; this is shown to primarily be due to steric effects.
Enthalpy-Entropy Compensation Effect in Oxidation Reactions by Manganese(IV)-Oxo Porphyrins and Nonheme Iron(IV)-Oxo Models
Guo, Mian,Zhang, Jisheng,Zhang, Lina,Lee, Yong-Min,Fukuzumi, Shunichi,Nam, Wonwoo
supporting information, p. 18559 - 18570 (2021/11/22)
"Enthalpy-Entropy Compensation Effect"(EECE) is ubiquitous in chemical reactions; however, such an EECE has been rarely explored in biomimetic oxidation reactions. In this study, six manganese(IV)-oxo complexes bearing electron-rich and -deficient porphyrins are synthesized and investigated in various oxidation reactions, such as hydrogen atom transfer (HAT), oxygen atom transfer (OAT), and electron-transfer (ET) reactions. First, all of the six Mn(IV)-oxo porphyrins are highly reactive in the HAT, OAT, and ET reactions. Interestingly, we have observed a reversed reactivity in the HAT and OAT reactions by the electron-rich and -deficient Mn(IV)-oxo porphyrins, depending on reaction temperatures, but not in the ET reactions; the electron-rich Mn(IV)-oxo porphyrins are more reactive than the electron-deficient Mn(IV)-oxo porphyrins at high temperature (e.g., 0 °C), whereas at low temperature (e.g., -60 °C), the electron-deficient Mn(IV)-oxo porphyrins are more reactive than the electron-rich Mn(IV)-oxo porphyrins. Such a reversed reactivity between the electron-rich and -deficient Mn(IV)-oxo porphyrins depending on reaction temperatures is rationalized with EECE; that is, the lower is the activation enthalpy, the more negative is the activation entropy, and vice versa. Interestingly, a unified linear correlation between the activation enthalpies and the activation entropies is observed in the HAT and OAT reactions of the Mn(IV)-oxo porphyrins. Moreover, from the previously reported HAT reactions of nonheme Fe(IV)-oxo complexes, a linear correlation between the activation enthalpies and the activation entropies is also observed. To the best of our knowledge, we report the first detailed mechanistic study of EECE in the oxidation reactions by synthetic high-valent metal-oxo complexes.
Photocatalytic C-H activation and the subtle role of chlorine radical complexation in reactivity
Yang, Qiaomu,Wang, Yu-Heng,Qiao, Yusen,Gau, Michael,Carroll, Patrick J.,Walsh, Patrick J.,Schelter, Eric J.
, p. 847 - 852 (2021/05/28)
The functionalization of methane, ethane, and other alkanes derived from fossil fuels is a central goal in the chemical enterprise. Recently, a photocatalytic system comprising [CeIVCl5(OR)]2- [CeIV, cerium(IV); OR, -OCH3 or -OCCl2CH3] was disclosed. The system was reportedly capable of alkane activation by alkoxy radicals (RO·) formed by CeIV-OR bond photolysis. In this work, we present evidence that the reported carbon-hydrogen (C-H) activation of alkanes is instead mediated by the photocatalyst [NEt4]2[CeCl6] (NEt4+, tetraethylammonium), and RO· are not intermediates. Spectroscopic analyses and kinetics were investigated for C-H activation to identify chlorine radical (Cl·) generation as the ratelimiting step. Density functional theory calculations support the formation of [Cl·][alcohol] adducts when alcohols are present, which can manifest a masked RO· character. This result serves as an important cautionary note for interpretation of radical trapping experiments.
