Photocatalytic Selective Reduction by TiO2 of 5-Nitrosalicylic Acid Ethyl Ester: A Mild Route to Mesalazine

Molinari, Alessandra; Mazzanti, Michele; Fogagnolo, Marco

doi:10.1007/s10562-019-02993-3

Cited by 7 publications

(5 citation statements)

References 23 publications

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“…Figure 4 shows the IR spectra of NBA adsorbed on CdS/TiO2 both kept in the dark and irradiated in the visible region (λ ≥ 420 nm). In the infrared spectrum of NBA adsorbed on the material before irradiation (dashed line), two absorption bands at 1541 cm −1 and 1346 cm −1 which are attributable to the asymmetric and symmetric N-O stretching frequencies of the nitro group are recognizable [28,29,33]. This indicates that the nitroaromatic molecule interacted with the TiO2 surface mainly through this functional group, in agreement to what has been previously observed [29].…”

Section: Photocatalytic Properties Of Cds/tio2-(1-4)supporting

confidence: 87%

“…Since amines can be obtained by catalytic hydrogenation of aromatic nitro compounds under harsh reaction conditions and selective reduction of the nitro group in the presence of other reducible functional groups such as carbonyl, halide and cyano, it is difficult to achieve the development of a simple, low impact and highly efficient method for the selective reduction of the nitro group. We and many other researchers demonstrated that photoexcited TiO 2 [28][29][30][31][32][33], doped TiO 2 [34] or composite photocatalysts based on TiO 2 [35][36][37] were able to catalyze the reduction of nitroaromatic compounds to the corresponding anilines. In addition, when two reducible functionalities are simultaneously present in the molecules (e.g., p-nitrobenzaldehyde), the selectivity of the reaction could be controlled by the presence of small alkali metal ions such as Li + and Na + [38].…”

Section: Introductionmentioning

confidence: 93%

“…In the infrared spectrum of NBA adsorbed on the material before irradiation (dashed line), two absorption bands at 1541 cm −1 and 1346 cm −1 which are attributable to the asymmetric and symmetric N-O stretching frequencies of the nitro group are recognizable [28,29,33]. This indicates that the nitroaromatic molecule interacted with the TiO 2 surface mainly through this functional group, in agreement to what has been previously observed [29]. Therefore, visible irradiation should involve the nitro group and, accordingly, the stretching values assigned to the N-O vibrations almost completely disappear in the IR spectrum after the irradiation period (solid line).…”

Section: Photocatalytic Properties Of Cds/tio 2 -(1-4)mentioning

confidence: 99%

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Composite CdS/TiO2 Powders for the Selective Reduction of 4-Nitrobenzaldehyde by Visible Light: Relation between Preparation, Morphology and Photocatalytic Activity

et al. 2022

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A series of composite CdS/TiO2 powders was obtained by nucleation of TiO2 on CdS nanoseeds. This combination presents the appropriate band edge position for photocatalytic redox reactions: visible light irradiation of CdS allows the injection of electrons into dark TiO2, increasing the lifetimes of separated charges. The electrons have been used for the quantitative photoreduction of 4-nitrobenzaldehyde to 4-aminobenzaldehyde, whose formation was pointed out by 1H NMR and ESI-MS positive ion mode. Concomitant sacrificial oxidation of 2-propanol, which was also the proton source, occurred. The use of characterization techniques (XRD, N2 adsorption-desorption) evidenced the principal factors driving the photocatalytic reaction: the nanometric size of anatase crystalline domains, the presence of dispersed CdS to form an extended active junction CdS/anatase, and the presence of mesopores as nanoreactors. The result is an efficient photocatalytic system that uses visible light. In addition, the presence of TiO2 in combination with CdS improves the stability of the photoactive material, enabling its recyclability.

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Section: Photocatalytic Properties Of Cds/tio2-(1-4)supporting

confidence: 87%

Section: Introductionmentioning

confidence: 93%

Section: Photocatalytic Properties Of Cds/tio 2 -(1-4)mentioning

confidence: 99%

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Composite CdS/TiO2 Powders for the Selective Reduction of 4-Nitrobenzaldehyde by Visible Light: Relation between Preparation, Morphology and Photocatalytic Activity

et al. 2022

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“…Although it has already been reported that illuminated TiO 2 is able to reduce nitroaromatic molecules to the corresponding anilines [25][26][27][28][29][30], as far as we know, the one presented here is the first example concerning the possibility of reaching two simultaneous goals by photocatalysis, namely the removal of a waste from water by converting it into useful building blocks.…”

Section: Introductionmentioning

confidence: 88%

Turning Waste into Useful Products by Photocatalysis with Nanocrystalline TiO2 Thin Films: Reductive Cleavage of Azo Bond in the Presence of Aqueous Formate

et al. 2020

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UV-photoexcitation of TiO2 in contact with aqueous solutions of azo dyes does not imply only its photocatalytic degradation, but the reaction fate of the dye depends on the experimental conditions. In fact, we demonstrate that the presence of sodium formate is the switch from a degradative pathway of the dye to its transformation into useful products. Laser flash photolysis experiments show that charge separation is extremely long lived in nanostructured TiO2 thin films, making them suitable to drive both oxidation and reduction reactions. ESR spin trapping and photoluminescence experiments demonstrate that formate anions are very efficient in intercepting holes, thereby inhibiting OH radicals formation. Under these conditions, electrons promoted in the conduction band of TiO2 and protons deriving from the oxidation of formate on photogenerated holes lead to the reductive cleavage of N=N bonds with formation and accumulation of reduced intermediates. Negative ion ESI–MS findings provide clear support to point out this new mechanism. This study provides a facile solution for realizing together wastewater purification and photocatalytic conversion of a waste (discharged dye) into useful products (such as sulfanilic acid used again for synthesis of new azo dyes). Moreover, the use of TiO2 deposited on an FTO (Fluorine Tin Oxide) glass circumvents all the difficulties related to the use of slurries. The obtained photocatalyst is easy to handle and to recover and shows an excellent stability allowing complete recyclability.

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“…The photocatalytic reduction of 5-nitrosalicylic acid ethyl ester results in the transformation of the nitro group into the amino functionality to produce mesalazine (Scheme 53 ). 105 The reaction was carried out under mild reaction conditions using dispersed TiO 2 photocatalyst, a mixture of acetonitrile/2-propanol as solvent, and a light source. The presence of solvent acts as sacrificial hole scavenger as well as proton source.…”

Section: Photocatalytic Reduction Of Nitro Compounds To Valuable Scaf...mentioning

confidence: 99%

Recent Developments in Photocatalytic Reduction of Nitro Compounds to Valuable Scaffolds

Aggarwal

Bala

Malik

et al. 2023

Synlett

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The reduction of nitro compounds is one of the fundamental organic transformations and ascertain wide applicability in industrial chemistry, synthesis of valuable scaffolds, fine chemical synthesis as well as environmental applicability for decontamination process. The transformation involves the conversion of nitro compounds to valuable scaffolds including amino, nitroso, hydroxyl amines, azo and hydrazo compounds. Conventional approaches for the reduction of nitro compounds involves the environmentally harmful stoichiometric reagents, high boiling reaction media, tedious processes, and harsh reaction conditions with high temperature and pressure. Additionally, the selectivity always remains a serious concern associated with the process due to the possibilities of several stable intermediate formation in the reaction pathway of reduction of nitro compounds. Nitro compounds are also of serious environmental concerns being a part of most harmful and high-priority classes of pollutants mainly released from industrial effluents, agricultural waste, and human sewage. A simple degradation of these pollutants bearing nitro group just removes the pollutants, however, the selective reduction of nitro group to valuable functionalities as mentioned above provides the industrially important scaffolds. Herein, the present review article is focused on the recent developments in the photocatalytic reduction of nitro compounds to valuable scaffolds.

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Photocatalytic Selective Reduction by TiO2 of 5-Nitrosalicylic Acid Ethyl Ester: A Mild Route to Mesalazine

Cited by 7 publications

References 23 publications

Composite CdS/TiO2 Powders for the Selective Reduction of 4-Nitrobenzaldehyde by Visible Light: Relation between Preparation, Morphology and Photocatalytic Activity

Composite CdS/TiO2 Powders for the Selective Reduction of 4-Nitrobenzaldehyde by Visible Light: Relation between Preparation, Morphology and Photocatalytic Activity

Turning Waste into Useful Products by Photocatalysis with Nanocrystalline TiO2 Thin Films: Reductive Cleavage of Azo Bond in the Presence of Aqueous Formate

Recent Developments in Photocatalytic Reduction of Nitro Compounds to Valuable Scaffolds

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