CuO/CaO as a solid reducing reagent for nitroarenes: combined effect of oxygen vacancies and surface basicity

Rajendran, K.; Akash, S.; Roshni, M.; Nanjan, Pandurangan; Jagadeesan, Dinesh

doi:10.1007/s43538-022-00095-0

Cited by 3 publications

(4 citation statements)

References 48 publications

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“…The area under Ov signal is around 51 % of the total O1s signal (includes Ov, O L and O A ) in CaO/CuO as compared to 41 % in the case of bulk CuO [19] . Consistent with earlier observations, the relative concentration of the vacancies were found to be higher on CaO/CuO [36–38] . Analysis of Raman spectra of the bulk CuO (Red) showed bands at 291, 337 and 624 cm −1 corresponding to A 1g , B 1g and B 2g modes of vibrations, respectively (Figure 2c).…”

Section: Resultssupporting

confidence: 90%

“…[19] Consistent with earlier observations, the relative concentration of the vacancies were found to be higher on CaO/CuO. [36][37][38] Analysis of Raman spectra of the bulk CuO (Red) showed bands at 291, 337 and 624 cm À 1 corresponding to A 1g , B 1g and B 2g modes of vibrations, respectively (Figure 2c). The position of bands were in agreement with the reported values of CuO at 296, 340 and 630 cm À 1 .…”

Section: Resultssupporting

confidence: 89%

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Oxygen Vacancy Mediated Reactivity of CaO/CuO Composite for the Synthesis of Amino‐N‐heterocycles

Rajendran,

Madampadi,

Shee

et al. 2023

ChemCatChem

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Utilising the oxygen‐vacancy‐mediated reactivity of CaO/CuO and hydrazine monohydrate in isopropyl alcohol at 353 K, a variety of amino‐derivatives of N‐heterocycles, including pyridine, indole, quinoline, isoquinoline, and benzothiazole, have been selectively synthesised by reducing their nitro analogues. It is demonstrated that CaO/CuO composite is a reusable, solvent‐resilient solid reducing agent that can reduce a variety of nitro‐N‐heterocyclic substrates. The critical role of the structure of CaO/CuO on the nitro‐reduction activity has been studied using spectroscopy and microscopy. DFT simulations indicate the facile formation of oxygen vacancies (EO,vac =‐ 43.4 kJ/mol) on the interface of CaO/CuO surface under reducing environment. The presence of CaO facilitated a stronger interaction of the nitro‐substrate on the oxygen vacant CuO (111) surface, resulting into a significantly lower activation energy (Ea = 21.9 kJ/mol) for N‐O dissociation. The reaction could be scaled up from 1 to 12 mmol of substrate. CaO/CuO is a reusable and a cost‐effective alternative to the conventional catalyst (Pd/C, Pt/C).

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 89%

Oxygen Vacancy Mediated Reactivity of CaO/CuO Composite for the Synthesis of Amino‐N‐heterocycles

Rajendran,

Madampadi,

Shee

et al. 2023

ChemCatChem

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“…There was a loss in the activity though, which correlated well with the loss in the surface V o . Eventually, modified CuO showed better reactivity and stability [39–43] …”

Section: Chemical Processes Associated With the Nitro‐reductionmentioning

confidence: 99%

“…Eventually, modified CuO showed better reactivity and stability. [39][40][41][42][43] Although metal is an important constituent in these oxides, the CuO may stand apart from the classical metal-acid or metal-H 2 -based catalysts (Scheme 1) by the nature of the reactivity of the active sites. The V o -mediated reactive solids present a new scope as a non-noble metal-based reaction system for the synthesis of amines.…”

Section: Catalytic Systemmentioning

confidence: 99%

Harnessing the Oxygen Vacancies in Metal Oxides for Nitroreduction

Rajendran,

Jagadeesan

2024

ChemCatChem

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Oxygen vacancies are one of the prominent types of defects in metal oxides. In addition to their role in modifying the electronic properties in solids, these sites have been shown to activate chemical bonds. As a result, the use of defect‐rich metal oxides in the organic transformations is promising. The article gives an overview of various chemical processes that are in use for the chemical reduction of aromatic nitro compounds to amines. Recently, application of oxygen vacancies in transition metal oxide for the selective reduction of aromatic nitro compounds to the corresponding amines has emerged as a new method of synthesis of amines.

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Reduction of Electron-Rich Nitro Heteroarenes; A Comprehensive Review

Nanjan

Vengatesh

2022

COC

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Amino heterocycles are important in drug design due to their unique intrinsic and physicochemical properties. Though these molecules look simple, their selective reduction is challenging because of their rich electron density in the ring. Additionally, reducing nitro groups in heterocycles is crucial in designing different materials. With this in view, several reduction methods have been developed and applied to various heterocyclic compounds. However, there is no dedicated report on these special types of compounds. With careful analysis, the studies are systematically summarized from conventional methods to advance materials based on their catalytic activity, durability, recyclability, and stability. Further, detailed insights are discussed to motivate chemists working in catalysts.

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CuO/CaO as a solid reducing reagent for nitroarenes: combined effect of oxygen vacancies and surface basicity

Cited by 3 publications

References 48 publications

Oxygen Vacancy Mediated Reactivity of CaO/CuO Composite for the Synthesis of Amino‐N‐heterocycles

Oxygen Vacancy Mediated Reactivity of CaO/CuO Composite for the Synthesis of Amino‐N‐heterocycles

Harnessing the Oxygen Vacancies in Metal Oxides for Nitroreduction

Reduction of Electron-Rich Nitro Heteroarenes; A Comprehensive Review

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