Oxygen Centered Radicals in Iodine Chemical Oscillators

Stanisavljev, Dragomir R.; Milenković, Maja C.; Mojović, Miloš; Popović‐Bijelić, Ana

doi:10.1021/jp203601w

Cited by 29 publications

(34 citation statements)

References 33 publications

(39 reference statements)

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“…[17b] However,n oe fficient strategy has yet been reported to suppress nonproductive pathways (i.e., oxidative decomposition of oxidant) for I + /H 2 O 2 catalysis,a lthough the use of hydrogen peroxide is highly preferable because it is less expensive and more atom-economical than alkyl hydroperoxide. [22] Because the oxidative decomposition of hydrogen peroxide might involve radical intermediates, [20,23] and the present oxidative coupling reaction might proceed via an ionic mechanism, we found that the non-productive pathways of I + /H 2 O 2 catalysis could be suppressed by using ac atalytic amount of ar adical trapping agent such as a-phenyl-N-tertbutylnitrone (PBN) or 5-(diethoxyphosphoryl)-5-methyl-1pyrroline N-oxide (DEPMPO) ( Table 1, entries 4a nd 5, for further investigation of additives,s ee Table S1). Notably,i n comparison with the striking results using catalyst 3b shown in entry 4, unreacted 1b was almost recovered with the use of catalysts 3a, 3c and 3d under the same mild conditions ( Table 1, entry 6).…”

Section: Resultsmentioning

confidence: 99%

Chemo‐ and Enantioselective Oxidative α‐Azidation of Carbonyl Compounds

et al. 2020

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We report high‐performance I+/H2O2 catalysis for the oxidative or decarboxylative oxidative α‐azidation of carbonyl compounds by using sodium azide under biphasic neutral phase‐transfer conditions. To induce higher reactivity especially for the α‐azidation of 1,3‐dicarbonyl compounds, we designed a structurally compact isoindoline‐derived quaternary ammonium iodide catalyst bearing electron‐withdrawing groups. The nonproductive decomposition pathways of I+/H2O2 catalysis could be suppressed by the use of a catalytic amount of a radical‐trapping agent. This oxidative coupling tolerates a variety of functional groups and could be readily applied to the late‐stage α‐azidation of structurally diverse complex molecules. Moreover, we achieved the enantioselective α‐azidation of 1,3‐dicarbonyl compounds as the first successful example of enantioselective intermolecular oxidative coupling with a chiral hypoiodite catalyst.

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Section: Resultsmentioning

confidence: 99%

Chemo‐ and Enantioselective Oxidative α‐Azidation of Carbonyl Compounds

et al. 2020

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“…to give the a-azido products via S N 2' type addition of ammonium azide.O nt he other hand, based on the control experiments (Table S8), in situ generated I + species such as hypoiodite might be the catalytic active species for the present oxidative a-azidation reactions,a si no ur previous oxidative coupling reactions. [19,20,23] Based on these results, ap roposed catalytic mechanism is depicted in Scheme 6c, which consists of three main steps:oxidation of iodide to the hypoiodite active species,( decarboxylative) a-iodination of 1 or 5,and nucleophilic azidation of the corresponding a-iodo intermediate 9 or 10.…”

Section: Forschungsartikelmentioning

confidence: 99%

Chemo‐ and Enantioselective Oxidative α‐Azidation of Carbonyl Compounds

et al. 2020

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“…Smatra se da se reakcije koje inhibitorno utiču na oscilatornu dinamiku, uglavnom odigravaju sa prisutnim HOO• radikalima generisanim u BR reakciji. Ovo, naravno, treba uzeti sa rezervom jer je BR reakcija potencijalni generator i drugih radikalskih vrsta (IO2•, I•, HO•, MAH•, IMA•, poslednja dva su radikali nastali iz malonske kiseline (MA) i jodomalonske kiseline (IMA)), ali i neradikalskih vrsta kao što su HIO2, HIO, I2, I - [33][34][35][36][37][38]. Izazvane promene u oscilatornoj dinamici dodatkom aktivnog analita/aditiva, se uspešno koriste za određivanje koncentracije aktivnog analita, ali i njegove potencijalne antioksidativne/antiradikalske aktivnosti [30].…”

Section: Uvodunclassified

Oscillatory reaction as a system detector for doped and undoped phosphate tungsten bronzes

Maksimović

Joksović

et al. 2018

Hem Ind

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Phosphate tungsten bronzes, obtained by thermal treatment, are insufficiently investigated bronzes and there is scarce literature data on their chemical behavior and structure. Due to high-sensitivity of the Briggs-Rauscher (BR) reaction to addition of different analytes, this oscillatory reaction presents a potentially important chemical system for investigation and characterization of phosphate-tungsten bronzes, doped and undoped. The reaction mixture for the oscillatory BR reaction typically consists of H2O2, HClO4, KIO3, Mn(II) (catalyst), and CH2(COOH)2 (malonic acid, as an organic substrate). This paper deals with phosphate tungsten bronzes (PWB) and lithium doped phosphate tungsten bronzes (LiPWB) and their effects on the Briggs-Rauscher reaction dynamics. It is shown that the addition of phosphate tungsten bronzes decreases the oscillatory period length in this reaction. Furthermore, the obtained results show that PWB has a stronger influence on the BR reaction dynamics then LiPWB. In both cases, the oscillatory period is a linear function of the added bronze mass. The obtained linear functions can be successfully used for determination of the unknown bronze mass. Furthermore, due to different slopes of these functions, the Briggs-Rauscher reaction can be used as a system-detector for lithium doped and undoped phosphate tungsten bronzes. In order to elucidate the mechanism of bronze action, the inductively coupled plasma optical emission spectrometry (ICP-OES) was used to measure the total contents of K, Mn, W, Li. The aliquots of the above solution (i.e. CH2(COOH)2, MnSO4, HClO4, KIO3 but without H2O2) with the identical masses of PWB and LiPWB were examined. For the sake of comparison, contents of the metals in the solution without the bronze addition were measured, as well. Results obtained by the ICP-OES analysis show that the bronze structure is disturbed in the strong oxidizing environment (iodate in acidic solution) so that both, tungsten and lithium, leach into the BR solution. Accordingly, the proposed mechanism of the bronze action is probably by the reaction of tungsten ion with hydrogen-peroxide resulting in formation of a tungsten-peroxo complex. This complex is a stronger oxidizing agent then hydrogen peroxide itself. Thus, formation of the tungsten-peroxo complex potentially affects the kinetics of the Briggs-Rauscher reaction. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172015, Grant no. III45001 and Grant no. III45014]

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Oxygen Centered Radicals in Iodine Chemical Oscillators

Cited by 29 publications

References 33 publications

Chemo‐ and Enantioselective Oxidative α‐Azidation of Carbonyl Compounds

Chemo‐ and Enantioselective Oxidative α‐Azidation of Carbonyl Compounds

Chemo‐ and Enantioselective Oxidative α‐Azidation of Carbonyl Compounds

Oscillatory reaction as a system detector for doped and undoped phosphate tungsten bronzes

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