Search results for "Green chemistry"
showing 10 items of 159 documents
Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural in Aqueous Medium over Nb2O5-Based Catalysts
2021
The catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) in water was performed in the presence of pristine Nb2O5 and composites containing Nb and Ti, Ce or Zr oxides. In all experiments, fructose was converted to HMF using water as the solvent. The catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, N2 physical adsorption, infrared and Raman spectroscopy and temperature-programmed desorption of NH3. Experimental parameters such as fructose initial concentration, volume of the reacting suspension, operation temperature, reaction time and amount of catalyst were tuned in order to optimize the catalytic reaction process. The highest selectivit…
Photochemical sample treatment: a greener approach to chlorobenzene determination in sediments.
2014
Abstract Due to worker׳s exposure, solvent and stationary phases׳ consumption, sample purification is one of the most polluting steps in analytical procedures for determination of organic pollutants in real samples. The use of photochemical sample treatment represents a valid alternative methodology for extracts clean up allowing for a reduction of the used amount of organic solvents. In this paper we report the first application on the photolytic destruction of organic substances to eliminate some of the interferences in the analysis of Chlorobenzenes in sediment samples. The method׳s efficiency and robustness were compared with classic silica column purification process currently used in …
DEEP EUTECTIC SOLVENTS E LIQUIDI IONICI: SOLVENTI PER LO SVILUPPO DI PROCESSI ECO-COMPATIBILI
2020
L’obiettivo di questi tre anni di Dottorato è stato lo studio e l’utilizzo nuovi solventi di reazione in grado di sostituire i solventi organici classici. In particolare sono stati studiati i Deep Eutectic Solvent (DES) e le miscele di Liquidi Ionici (IL). I DES sono stati utilizzati come solventi per lo studio di reazioni organiche, usate per la formazione di nuovi legami C-C. Nello specifico sono state studiate la reazione di Diels-Alder, e diverse reazioni di coupling C-C catalizzate da Pd. In seguito, i DES sono stati utilizzati per la formazione di nuovi gel supramolecolari, chiamati eutectogel. Questi gel sono stati formati usando come gelator amminoacidi naturali, consentendo quindi …
22nd International Scientific Conference “EcoBalt 2021”: Book of Abstracts (Riga, Latvia, October 21–23, 2021)
2021
The abstract book contains abstracts of the participants of the 22nd International Scientific Conference "EcoBalt 2021".
Micro(Nano)plastic analysis: a green and sustainable perspective
2022
Within the last years aspects such as green, eco-friendly and sustainable are making their way into analytical chemistry. The field has changed with the introduction of these concepts. Information on the consumption of toxic solvents and energy is now a part of everyday life. This green analytical chemistry could be playing a pioneering role in the analysis of micro(nano)plastics in the environment. We discuss the roles of green analytical and sustainability within micro(nano) plastics determination and its possible applications. We explain its many advantages, like their function to preserve the environment and operator health or their role in the so-called eco-friendly methodologies, but …
New Approach to 1,4-Benzoxazin-3-ones by Electrochemical C-H Amination.
2017
1,4-Benzoxazin-3-ones are important structural motifs in natural products and bioactive compounds. Usually the synthesis of benzoxazinones requires transition metal catalysts and pre-functionalized substrates, e.g. aryl halides. However, the anodic C,H amination of phenoxy acetates offers a very efficient and sustainable access to these heterocycles. The herein presented electrochemical protocol can be applied to a broad scope of alkylated substrates. Even tert-butyl moieties or halogen substituents are compatible with this versatile method.
Electrochemical Amination of Less-Activated Alkylated Arenes Using Boron-Doped Diamond Anodes
2016
The anodic C–H amination of aromatic compounds is a powerful and versatile method for the synthesis of aniline derivatives. By using boron-doped diamond (BDD) anodes, a method initially described by Yoshida et al. for electron-rich arenes was expanded to less-activated aromatic systems e.g., simple alkylated benzene derivatives. Anodes based on sp3 carbon seem to be the key for the electrochemical amination reaction. The corresponding primary anilines are obtained in good yields. Despite the cationic intermediates of the electrolytic reaction tert-butyl moieties are tolerated.
Synthesis of Highly Functionalized N , N ‐Diarylamides by an Anodic C, N ‐Coupling Reaction
2019
We report an innovative, sustainable and straightforward protocol for the synthesis of N,N-diarylamides equipped with nonprotected hydroxyl groups by using electrosynthesis. The concept allows the application of various substrates furnishing diarylamides with yields up to 57 % within a single and direct electrolytic protocol. The method is thereby easy to conduct in an undivided cell with constant current conditions offering a versatile and short-cut alternative to conventional pathways.
A Bipyridine‐Palladium Derivative as General Pre‐Catalyst for Cross‐Coupling Reactions in Deep Eutectic Solvents
2019
A versatile and DES‐compatible bipyridine palladium complex has been developed as a general pre‐catalyst for different cross‐coupling reactions (Hiyama, Suzuki‐Miyaura, Heck‐Mizoroki and Sonogashira) in deep eutectic solvents. Hydrogen bond capacity of the ligand allows to keep the excellent level of results previously obtained in classical organic solvents. Palladium pre‐catalyst showed a high catalytic activity for many cross‐coupling reactions, demonstrating a great versatility and applicability. Also, this methodology employs sustainable solvents as a reaction medium and highlights the potential of DES as alternative solvents in organometallic catalysis. The catalyst and DES were easily…
Electrochemical Synthesis of 5-Aryl-phenanthridin-6-one by Dehydrogenative N,C Bond Formation.
2018
Currently, the general synthesis of 5-aryl-phenanthridin-6-ones relies on the involvement of metal catalysis. Despite the urgent demand for green alternatives, avoiding synthetic routes that require transition metals for key roles is still challenging. Electrochemical efforts employing a constant potential protocol in divided cells revealed a possible alternative to the catalytic approach. A constant current protocol, undivided cells, and a remarkably low supporting electrolyte concentration enable a novel access to N-aryl-phenanthridin-6-ones by anodic N,C bond formation using directly generated amidyl radicals. Easy accessible starting materials, a broad scope of applicable functional gro…