Copper-Mediated Oxygenation of Nitronate to Nitrite and Acetone in a Copper(I) Nitronate Complex

Balogh-Hergovich, Éva; Speier, Gábor; Hüttner, Gottfried; Zsolnai, László

doi:10.1021/ic980246t

Cited by 12 publications

(9 citation statements)

References 48 publications

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“…The view of the molecule in Figure 5 shows that the geometry around the copper(II) centre is similar to that of the Cu II -(NO 2 )(tmeda) complex with an elongated rhombic octahedral CuO 2 N 2 O 2 chromophore and a (4ϩ2*)-type coordination, involving two off-the-z-axis bonds. Selected bond lengths and angles given in Table 3 [31] This is similar to the findings for the structures of Cu I (NP)(PPh 3 ) 2 [23] and Fe III (NP) 3 . [32] The CϪN distances are somewhat longer in Cu II (NP) 2 (1.34Ϫ1.35 Å ), however, its structure consists of chains of Cu II (NP) 2 units.…”

Section: Characterisation Of Cu II (Np) 2 (Tmeda)supporting

confidence: 71%

“…(2) In order to gain more insight into the mechanism of these reactions we initiated studies on copper-and iron-mediated oxygenations of nitroalkanes. We could show that isopropyl nitronate, ligated to a copper ion, can be oxygenated to (nitrito)copper species and acetone, [23] and in the presence of copper metal, as a precursor, nitroalkanes are easily transformed to aldehydes or ketones by dioxygen. [24] In this paper we present kinetic and spectroscopic data on this reaction, the X-ray structures of intermediates and propose a plausible mechanism for the oxygenation as a 2-nitropropane dioxygenase mimicking reaction.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics and Mechanism of the Copper-Catalysed Oxygenation of 2-Nitropropane

Balogh-Hergovich

Gréczi

Kaizer

et al. 2002

Eur. J. Inorg. Chem.

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Primary and secondary nitro compounds react with dioxygen in the presence of copper metal and N ligands such as N,N,NЈ,NЈ-tetramethylethylenediamine (tmeda), 2,2Ј-bipyridine (bpy), and 1,10-phenantroline (phen) in various solvents to form aldehydes or ketones. More coordinating solvents as well as donor N ligands accelerate the reaction remarkably. The oxygenolysis of 2-nitropropane (NPH) in the presence of copper and tmeda in DMF results in acetone and acetone oxime. The amount of tmeda influences the chemoselectivity, higher tmeda concentrations preferentially lead to the formation of the oxime. The kinetics of the reaction, measured at 90°C, resulted in a rate equation of first-order dependence on copper and dioxygen and second-order dependence on 2-nitropropane. The rate constant, activation

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Section: Characterisation Of Cu II (Np) 2 (Tmeda)supporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of the Copper-Catalysed Oxygenation of 2-Nitropropane

Balogh-Hergovich

Gréczi

Kaizer

et al. 2002

Eur. J. Inorg. Chem.

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“…The DRIFT spectrum of 1-CH 2 NO 2 also contains a band at 1600 cm –1 assigned as the ν(CN) mode of the nitromethanate ligand. The frequency of this band is consistent with significant CN double-bond character and similar to that reported for κ 2 - O , O -nitromethanate complexes. − The DRIFT spectrum of 1-OPh shows new bands corresponding to ν(C–H) modes of the phenoxide group at 2989 and 3010 cm –1 , ν(CC) modes at 1591 and 1491 cm –1 , and a C–O stretch at 1291 cm –1 . 1-CCPh exhibits a ν(CC) band at 2119 cm –1 that is in good agreement with those observed for related zinc acetylide species generated at the metal nodes of MFU-4 l .…”

Section: Resultssupporting

confidence: 83%

Using Postsynthetic X-Type Ligand Exchange to Enhance CO₂ Adsorption in Metal–Organic Frameworks with Kuratowski-Type Building Units

2021

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Postsynthetic modification methods have emerged as indispensable tools for tuning the properties and reactivity of metal−organic frameworks (MOFs). In particular, postsynthetic Xtype ligand exchange (PXLE) at metal building units has gained increasing attention as a means of immobilizing guest species, modulating the reactivity of framework metal ions, and introducing new functional groups. The reaction of a Zn−OH functionalized analogue of CFA-1 (1-OH, Zn(ZnOH) 4 (bibta) 3 , where bibta 2− = 5,5′-bibenzotriazolate) with organic substrates containing mildly acidic E−H groups (E = C, O, N) results in the formation of Zn−E species and water as a byproduct. This Brønsted acid−base PXLE reaction is compatible with substrates with pK a (DMSO) values as high as 30 and offers a rapid and convenient means of introducing new functional groups at Kuratwoski-type metal nodes. Gas adsorption and diffuse reflectance infrared Fourier transform spectroscopy experiments reveal that the anilide-exchanged MOFs 1-NHPh 0.9 and 1-NHPh 2.5 exhibit enhanced low-pressure CO 2 adsorption compared to 1-OH as a result of a Zn−NHPh + CO 2 ⇌ Zn−O 2 CNHPh chemisorption mechanism. The MFU-4l analogue 2-NHPh ([Zn 5 (OH) 2.1 (NHPh) 1.9 (btdd) 3 ], where btdd 2− = bis(1,2,3-triazolo)dibenzodioxin), shows a similar improvement in CO 2 adsorption in comparison to the parent MOF containing only Zn−OH groups.

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“…Oxidative cleavage of nitronates is a synthetically preferred method of converting nitroalkanes to carbonyl compounds, [57] but with one exception, [58] molecular oxygen has not been used as the oxidant, and the only in vitro reactions of dioxygen with nitronates reported are those of a nitronate-copper com-plex. [59,60] In contrast, oxidative denitrifications of nitroalkanes, catalysed by flavin-dependent enzymes of bacterial, fungal and plant origin [60][61][62][63] consume molecular oxygen, and as we have noted earlier, [44] at least one enzyme-catalysed denitrification involves a deprotonation of the nitroalkane by the carboxylate of an active site aspartate residue. [44] There are interesting parallels here, and perhaps also some warnings for the interpretation of data on deprotonations of nitroalkanes when these have been monitored by UV-Vis spectroscopy.…”

Section: Preparative Considerations and Preliminary Reactivity Studiesmentioning

confidence: 99%

The primary kinetic hydrogen isotope effect in the deprotonation of a nitroalkane by an intramolecular carboxylate group

Backstrom

Burton

Turega

et al. 2008

J of Physical Organic Chem

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The rates of racemization of optically active nitropentanoic acid, and 4-deuteronitropentanoic have been compared. The rate ratio (kie) is k H /k D ¼ 5.68(W0.17) at 31-C, in good agreement with that determined by Lewis et al. for base-catalysed deprotonations using iodine-trapping methods. In a more detailed study, optically active 4-nitro-4-phenylbutanoic acid (NPBA) has also been prepared and rates of racemization measured in dimethoxyethane:water. With less than a full equivalent of triethylamine, rates are proportional to [Et 3 N:]/[NPBA]. For 1 < [Et 3 N:]/[NPBA] < 2, rates are independent of the ratio, consistent with racemization being dominated by deprotonation of the nitroalkane by the intramolecular carboxylate group. The solvent isotope effect is k H 2 O =k D 2 O ¼ 0.73(W0.04) and rates of exchange with D 2 O are equal to rates of racemization. Comparison with rates of racemization by acetate of the methyl ester yielded an effective molarity (EM ¼ 13.7) for the intramolecular carboxylate. The kie for racemizations of NPBA and 4-deutero-NPBA is k H /k D ¼ 5.78 at 25-C, and for 20 < T < 50-C, E D a S E H a ¼ 5.5(W0.1) and A H /A D ¼ 0.63(W1.03). For the acetate catalysed racemizations of the methyl ester, 25-C, k H /k D ¼ 7.43 with E D a S E H a ¼ 5.2 kJ mol S1 and A H /A D ¼ 1.08. In neither case is there any indication of a major tunnelling contribution on the isotopic rate ratio. A hitherto unrecognised mode of decomposition of nitronic acids, involving direct reaction with dissolved oxygen, has been identified.

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Copper-Mediated Oxygenation of Nitronate to Nitrite and Acetone in a Copper(I) Nitronate Complex

Cited by 12 publications

References 48 publications

Kinetics and Mechanism of the Copper-Catalysed Oxygenation of 2-Nitropropane

Kinetics and Mechanism of the Copper-Catalysed Oxygenation of 2-Nitropropane

Using Postsynthetic X-Type Ligand Exchange to Enhance CO₂ Adsorption in Metal–Organic Frameworks with Kuratowski-Type Building Units

The primary kinetic hydrogen isotope effect in the deprotonation of a nitroalkane by an intramolecular carboxylate group

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Copper-Mediated Oxygenation of Nitronate to Nitrite and Acetone in a Copper(I) Nitronate Complex

Cited by 12 publications

References 48 publications

Kinetics and Mechanism of the Copper-Catalysed Oxygenation of 2-Nitropropane

Kinetics and Mechanism of the Copper-Catalysed Oxygenation of 2-Nitropropane

Using Postsynthetic X-Type Ligand Exchange to Enhance CO2 Adsorption in Metal–Organic Frameworks with Kuratowski-Type Building Units

The primary kinetic hydrogen isotope effect in the deprotonation of a nitroalkane by an intramolecular carboxylate group

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Using Postsynthetic X-Type Ligand Exchange to Enhance CO₂ Adsorption in Metal–Organic Frameworks with Kuratowski-Type Building Units