Scientific advances in sulfuric acid free toluene nitration

Sreedhar, I.; Singh, Manvendra; Raghavan, K. V.

doi:10.1039/c3cy00337j

Cited by 24 publications

(6 citation statements)

References 71 publications

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“…In this case, the system should be extensively rinsed with water after successful cleaning. In the context of a sustainable technology, the scientific community has been investigating methods to eliminate the use of acid solutions in experimental protocols dedicated to chemical synthesis, purification, or cleaning processes [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO₂ adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Tahir

Pandoli

Zaman³

et al. 2022

J. Phys. Commun.

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The synthesis of metal nanoparticles (NPs) using microfluidic reactors has become a major method for limiting reagent consumption and achieve a precise control of the morphological properties. Failure in realizing the reproducibility of the results is mostly associated with the accumulation of metallic nanostructures on the walls of the microfluidic devices, periodically removed by acid treatment. In this study, we show that ns-pulsed laser ablation (PLA) in water can be a safe, effective, and green method for the regeneration of clogged microfluidic reactors. The effect of the laser-pulse fluence on the removal of metallic nanostructures was studied for the first time on silver (Ag) thin films with a thickness of 50 nm deposited over SiO2 substrates, using 3-mercaptopropyl trimethoxysilane as a chemical adhesion layer. As point of novelty, the experimental results show that at low fluence (F < 0.1 J/cm2), ablation is principally caused by delamination of the thin film associated with the thermoelastic force while thermal processes inducing phase conversion of the metal dominate at higher fluence. Low-fluence regimes are better suited for the single-pulse removal of the nanomaterial, whereas in high F regimes, we observed melting and recondensation of the metal on the SiO2 surface so that multiple pulse interactions were necessary for complete ablation of the thin film. For the delamination and the phase transformation processes, the threshold fluences were 3.7 × 10−2 and 7.0 × 10−2 J/cm2, respectively. The experimental setup in the thermoelastic PLA regime was applied to unclog glass microfluidic devices used for synthesizing citrate-stabilized AgNPs. Using this simple and easily achievable laser-scanning experimental configuration, we demonstrated that PLA in water is a reliable and efficient technique, with results comparable to acidic treatment in terms of efficiency and time necessary for the complete removal of the Ag nanomaterial.

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Section: Introductionmentioning

confidence: 99%

Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO₂ adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Tahir

Pandoli

Zaman³

et al. 2022

J. Phys. Commun.

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“…TEMPO in the presence of cocatalytic NO x is desirable because they offer selective and efficient transformations for practical considerations. ,,, The majority of NO x sources, however, are toxic or corrosive inorganic or gaseous sources. Though MNO x , HNO x , , or NO x are widely used as stoichiometric oxidants or catalysts/cocatalysts in oxidation reactions (Scheme .1), many efforts have sought alternative reagents as NO x sources. ,, …”

Section: Introductionmentioning

confidence: 99%

Flavin Nitroalkane Oxidase Mimics Compatibility with NOx/TEMPO Catalysis: Aerobic Oxidization of Alcohols, Diols, and Ethers

et al. 2020

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Biomimetic flavin organocatalysts oxidize nitromethane to formaldehyde and NO x providing a relatively nontoxic, noncaustic, and inexpensive source for catalytic NO 2 for aerobic TEMPO oxidations of alcohols, diols, and ethers. Alcohols were oxidized to aldehydes or ketones, cyclic ethers to esters, and terminal diols to lactones. In situ trapping of NO x and formaldehyde suggest an oxidative Nef process reminiscent of flavoprotein nitroalkane oxidase reactivity, which is achieved by relatively stable 1,10-bridged flavins. The metal-free flavin/NO x /TEMPO catalytic cycles are uniquely compatible, especially compared to other Nef and NO xgenerating processes, and reveal selectivity over flavin-catalyzed sulfoxide formation. Aliphatic ethers were oxidized by this method, as demonstrated by the conversion of (−)-ambroxide to (+)-sclareolide.

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“…Concentrated mixtures of nitric and sulfuric acids, namely mixed acid, are widely employed in fine and bulk chemical production. − Even though several attempts and studies focused on the adoption of new nitrating agents, − mixed acids are still the most used reaction media in nitration processes . Thus, there is a need to better characterize the behavior of the system in order to predict the equilibrium concentration of the undissociated acids and the ionic species derived from their dissociation.…”

Section: Introductionmentioning

confidence: 99%

Ternary HNO₃–H₂SO₄–H₂O Mixtures: A Simplified Approach for the Calculation of the Equilibrium Composition

Russo

Marotta

Commodo

et al. 2018

Ind. Eng. Chem. Res.

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Concentrated ternary mixture of nitric acid, sulfuric acid, and water are often used in the chemical industry for a wide range of applications. Among these, nitrations of organic substrates are the most common. Nevertheless, there is still a poor understanding of speciation of the acids in the mixtures, and different simplified or semiempirical approaches have been found in the literature to model nitration kinetics by mixed acids. Most of the found investigations are relevant in restricted ranges of experimental conditions, resulting in a fragmentary vision. In this work, most of the approaches found in the literature were reviewed in order to define their limits of validity, and new empirical equations for the estimation of nitronium ion concentration are proposed. Moreover, on the basis of original experimental data, a simplified model is proposed to calculate the dissociation of acids at varying experimental conditions, and the main assumptions reported in the literature were verified. Adopted simplifying assumptions were verified at sulfuric acid concentrations higher than 2.1 mol•L −1 and nitric acid concentrations ranging from 2.0 to 11 mol•L −1 .

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Scientific advances in sulfuric acid free toluene nitration

Cited by 24 publications

References 71 publications

Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO₂ adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO₂ adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Flavin Nitroalkane Oxidase Mimics Compatibility with NOx/TEMPO Catalysis: Aerobic Oxidization of Alcohols, Diols, and Ethers

Ternary HNO₃–H₂SO₄–H₂O Mixtures: A Simplified Approach for the Calculation of the Equilibrium Composition

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Scientific advances in sulfuric acid free toluene nitration

Cited by 24 publications

References 71 publications

Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO2 adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO2 adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Flavin Nitroalkane Oxidase Mimics Compatibility with NOx/TEMPO Catalysis: Aerobic Oxidization of Alcohols, Diols, and Ethers

Ternary HNO3–H2SO4–H2O Mixtures: A Simplified Approach for the Calculation of the Equilibrium Composition

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Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO₂ adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Thermoelastic pulsed laser ablation of silver thin films with organic metal–SiO₂ adhesion layer in water: application to the sustainable regeneration of glass microfluidic reactors for silver nanoparticles

Ternary HNO₃–H₂SO₄–H₂O Mixtures: A Simplified Approach for the Calculation of the Equilibrium Composition