Innocuous Solvents Research Articles

Applications of Choline Chloride-Based Deep Eutectic Solvents as Sustainable Media and Catalyst in the Synthesis of Heterocyclic Scaffolds

Abstract:Deep eutectic solvents (DESs), also referred to as low transition temperature mixtures (LTTMs), have emerged as sustainable and cheap alternatives to conventional organic solvents in organic synthesis. This is attributed to their exceptional characteristics viz. easy preparation with readily available cheap materials, water compatibility, non-flammability, non-toxicity, biocompatibility, biodegradability, etc. All these properties label them as versatile and cost-effective green solvents. The first reported DES, choline chloride urea mixture has appeared as an innocuous solvent and catalyst in many organic transformations. This prospective DES combination has been applied extensively to the synthesis of a wide range of heterocyclic compounds including quinolones, spirooxindoles, etc. The conditions employed are relatively mild and do not require additional acid catalysts or organic solvents. This ecofriendly blend for the synthesis of heterocycles reports excellent yields of products with shorter reaction times and a simple workup procedure. Evaluating these merits, this review focuses on the recent literature published on the use of choline chloride-based DESs in the synthesis of a few important heterocyclic compounds.

Green synthesis of nanoparticles for varied applications: Green renewable resources and energy-efficient synthetic routes

Abstract This study presents an outline of the 12 principles of green relevance in nanomaterial synthesis. The goal of using green renewable resources is to protect the environment from negative effects, which can be achieved via several main directions, including the choice of innocuous solvents, such as supercritical (SC) fluids or water, and/or additives (i.e. stabilizers, capping, and reducing agents) such as polysaccharides, using alternative reaction circumstances, and the development of energy-efficient synthetic methods. This review shows how different green renewable resources routes are reducing the impact of chemical processes on the environment and how their benefit can be achieved in nanotechnology applications such as green energy.

A natural deep eutectic solvent as a novel dispersive solvent in dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of pesticide residues.

Current trends in analytical chemistry encourage the use of innocuous solvents to develop modern methods aligned with green chemistry. In this sense, natural deep eutectic solvents (NADESs) have emerged as a novel generation of green solvents which can be employed in sample treatments as an alternative to the toxic organic solvents commonly used so far. In this work, a new extraction method employs dispersive liquid-liquid microextraction based on a solid floating organic droplet (DLLME-SFO), by using a mixture composed of a less dense than water extraction solvent, 1-dodecanol, and a novel dispersive solvent, NADES. The methodology was proposed to extract and preconcentrate some pesticide residues (fipronil, fipronil-sulfide, fipronil-sulfone, and boscalid) from environmental water and white wine samples before analysis by liquid-chromatography coupled to ultraviolet detection (HPLC-UV). Limits of quantification (LOQs) lower than 4.5μgL-1, recoveries above 80%, and precision, expressed as RSD, below 15% were achieved in both samples showing that the proposed method is a powerful, efficient, and green alternative for the determination of these compounds and, therefore, demonstrating a new application for NADES in sample preparation. In addition, the DLLME-SFOD-HPLC-UV method was evaluated and compared with other reported approaches using the Analytical GREEnness metric approach, which highlighted the greenness of the proposed method.

Dynamic streamlined extraction of iridoids, anthocyanins and lipids from haskap berries

The European Commission recently authorized the placing of haskap (Lonicera caerulea L.) berries as a novel food on the EU market. It has been suggested that these berries have several health beneficial properties, due to their considerable content of highly valuable secondary metabolites, such as anthocyanins, phenolic acids, iridoids and fatty acids. Herein, we report a dynamic streamlined extraction process for iridoids and anthocyanins with supercritical carbon dioxide and ethanol as modifier. In particular, we have focused on the iridoids loganic acid and loganin, as well as on different hydroxylation patterns of the anthocyanins. The developed multiple step extraction process leads to initial separation of lipids at low ethanolic concentrations (1 vol%), followed by partial extraction of iridoids at 10 vol% ethanol and ultimately to combined extraction of iridoids and anthocyanins at higher ethanol amounts (>10 vol%). The sequential extraction can be performed in a closed system by automated variation of two innocuous solvents, but uses higher solvent amounts. In comparison to conventional ethanolic extraction, the dynamic streamlined yielded 97% of iridoids and about 7% more anthocyanins.

In situ formation of SnO2 nanoparticles on cellulose acetate fibrous membranes for the photocatalytic degradation of organic dyes

We present the development of a novel and green porous nanocomposite for photocatalytic applications, i.e. SnO2/cellulose acetate fibrous mats. The electrospinning method is adopted to form cellulose acetate/tin salt fibrous nanocomposite membranes, followed by a thermally activated conversion of the salt into SnO2 nanoparticles (NPs), directly in the solid fibrous matrix. Detailed microscopic investigations show that the porous composite membranes are composed by defect-free fibers (mean diameter 1.09 ± 0.35 μm) and SnO2 NPs (mean diameter 16.3 ± 3.4 nm), homogenously distributed in the whole volume and on the surface of the polymer fibers. The NPs act as oxidation sites under UV light irradiation, and, under the specific experimental conditions of this study, the total photodegradation efficiency is higher than 90 % for both anionic (methylene blue, MB) and cationic (methyl orange, MO) dyes. Data show that 54 % and 79 % of the MO and MB are mineralized, respectively, the rest being products of demethylation and hydroxylation processes. This novel in situ approach for the formation of pure SnO2 NPs directly in the polymeric fibers by using innocuous solvents, a polymer and a precursor agent with nontoxic byproducts, opens up the possibility to use solid SnO2-based polymer porous composites as efficient materials for water remediation of organic pollutants.

Exploitation of new chalcones and 4H-chromenes as agents for cancer treatment

Chalcone and chromene derivatives were synthesized in good yield through simple and effective reactions using innocuous solvents such as water and ethanol and high yielding aldol condensations. Generally, the reactions were performed at room temperature, leading to the isolation of highly pure compounds. These compounds were tested on breast cancer cells (MCF-7 and Hs578T) and breast non-neoplastic cells (MCF-10A). After determination of IC50 value, specific assays were performed to analyze the potential of these compounds, and those bearing halogenated substituents presented enhanced activity comparing to methoxyl or methyl groups. More specifically, the bromine atom was often present in the bioactive molecules that proceeded to the final assays and showed to be promising candidates for further studies. The selected chromene acted as a cell migration inhibitory agent and triggered regulated cell death associated with G2/M cell-arrest and microtubule destabilization. For chalcones, the results suggest an anti-proliferative activity. Also, results for combination-therapy potentiated the antitumor effect of doxorubicin and reduced cytotoxicity in MCF-10A cells.

Evaluation of cell wall damage by dimethyl sulfoxide in Candida species

Studies dealing with the response of microorganisms to oxidative stress require the dissolution of oxidant agents in an appropriate solvent. A commonly used medium is dimethyl sulfoxide, which has been considered as an innocuous polar solvent. However, we have observed significant differences between control, untreated cells and those receiving increasing amounts of the oxidant and hence increasing amounts of DMSO, to the maximum allowed of 1%. Here we show that, while this solvent does not influence yeast cell viability, it does affect expression of cell wall proteins as well as catalase activity. Therefore, its use in future studies of oxidative stress as an innocuous solvent should be reconsidered.

ChemInform Abstract: Green Chemistry for Nanoparticle Synthesis

AbstractReview: 50 refs.

DEVELOPMENT OF QUANTITATIVE HPTLC-DENSITOMETRY METHODS FOR ANALYSIS OF FAKE AND SUBSTANDARD PHARMACEUTICAL PRODUCTS FOLLOWING A MODEL APPROACH FOR TRANSFER OF TLC SCREENING METHODS: ALBENDAZOLE, AMODIAQUIN + ARTESUNATE, ACICLOVIR, AND AMOXICILLIN

A model procedure including sample and standard solution preparation, calibration curve establishment, assay of pharmaceutical products versus the label values, and validation of precision, accuracy, and sample peak purity and identification was applied for development of quantitative HPTLC-densitometry methods to be used in support of regulatory action against substandard and fake drugs. Methods for albendazole and amodiaquin + artesunate combined tablets were transferred from semiquantitative, visual TLC screening methods contained in an FDA Compendium developed by Kenyon and Layloff and GPHF Minilab manuals for use in countries with limited resources. A method for aciclovir was adapted from a previously published HPTLC method. The new methods involve use of a limited number of inexpensive and relatively innocuous solvents, EMD Millipore Premium Purity silica gel 60 F254 glass plates, automated standard and sample solution application with a CAMAG Linomat 4, and automated densitometry for detection, identification, and quantification with a CAMAG Scanner 3. Attempts to transfer Compendium and Minilab TLC methods for amoxicillin according to the model procedure were not successful, but a semiquantitative HPTLC-densitometry method on EMD Millipore cellulose F254 glass plates is described. These new methods can be more fully validated according to International Conference on Harmonization (ICH) guidelines or by interlaboratory studies if their applications require.

A synthesis of copper based metal-organic framework for O-acetylation of alcohols

A novel metal-organic framework, Cu–BDC was synthesized by static hydrothermal method using innocuous solvents and characterized by several techniques such as powder XRD, ESR, TG–DTA, elemental analysis, ICP-AES, SEM, EDXS, FT-IR, BET surface area, pore volume and pore size. The catalytic performance of Cu–BDC was explored for O-acetylation of alcohols under solvent-free conditions at room temperature. The catalyst exhibited remarkable activity and reusability affording the desired products in excellent yields.

Proline-coated gold nanoparticles as a highly efficient nanocatalyst for the enantioselective direct aldol reaction in water

Reported is an efficient approach to the synthesis of water-soluble proline-coated gold nanoparticles through a place exchange reaction between pentanethiolate stabilized gold nanoparticles and a proline-tethered amphiphilic thiol. Preliminary studies show that the nanocatalyst is highly active in an enamine type aldolisation leading to the desired product with nearly perfect diastereoselectivity and enantioselectivity using water as an innocuous solvent.

Ultrasound-promoted iodination of pyrazoles in aqueous medium

Several pharmacological activities have been devoted to pyrazole containing molecules. In particular, 4-iodopyrazoles have been employed as key starting materials in cross-coupling chemistry and metal-iodine exchange reactions that focus on the synthesis of such biologically important compounds. Unfortunately, existing methods for the synthesis of 4-iodopyrazoles are not in agreement with the environmental requirements due to a series of drawbacks including the use of large excess of reagents, the generation of toxic waste and long reaction times. Recently, we developed a fast and mild reaction condition for the iodination of aromatic compounds using an I 2 /H 2 O 2 system water as a nonflammable and innocuous solvent and ultrasonic irradiation as energy source. In this work, we present the application of this methodology for the iodination of pyrazoles (Scheme). Initially, a series of pyrazoles were efficiently prepared starting from 1,3-dicarbonyl compounds and hydrazines under ultrasonic irradiation. Three examples from the pyrazoles were subjected to the iodination condition shown above. Iodopyrazoles were obtained in 63-65% yields.

In situ growth of CdSe/CdS quantum dots inside and outside of MWCNTs

The CdSe/CdS quantum dots were grown in situ inside and outside of the multiwalled carbon nanotubes in an innocuous solvent and at a lower temperature. The CdSe/CdS-CNTs nanoheterostructures were characterized by TEM, HRTEM, EDS, XPS and PL. The CdSe/CdS nanocrystals with diameters about 5nm exhibit an improved PL emission.

Electrically forced coaxial nanojets for one-step hollow nanofiber design.

The outer liquid of a two-liquid coaxial electrified jet is gelled before the onset of natural instabilities to yield hollow nanofibers. By using sol-gel chemistry, innocuous solvents such as glycerol and olive oil, and electrohydrodynamics, it is possible to make such structures in a rather straightforward manner.

Solvent Extraction with Electrokinetic Multicommutation Analysis System

The feasibility of solvent extraction with an electrokinetic flow analysis (EKFA) system should be investigated further because of its non‐aqueous condition. As an example, the pre‐concentration and determination of copper, including on‐line color reaction, solvent extraction, and spectrometric determination were carried out by an electrokinetic multicommutation analysis system in this work. The proposed system consisted of one electroosmotic pump, four solenoid valves which were controlled by a personal computer, and a spectrometric detector. With the electroosmotic pump, sample and reagent solutions were aspirated into the system's color reaction section in small plugs, alternately, and were reacted sufficiently. Then, a plug of chloroform was inserted into the colored zone. The proposed system carried out solvent extraction by moving the sandwiched zone back and forth along its short extraction coil. After phase separation with a T‐shape separator, organic phase was determined in a flow detection cell of the spectrophotometer. The electroosmotic pump is a liquid delivery device with the merits of non‐pulsed and stable flow rate, simple pump structure, high driving efficiency, and facile flow control. Ethanol solution, a relatively high permittivity and innocuous solvent, was adopted as the pump carrier. In this paper, carrier additives were investigated further in order to improve the pump stability and efficiency (3.9 mL min−1 mA−1). The detection limit for copper was 0.03 mg L−1 (K = 3, n = 11) and its recoveries were in the range of 92–96% with a relative standard deviation of 5.2% (n = 3). The proposed method can provide a throughput of 20 samples per hour.

Interference of propylene glycol with the hole-board test.

Experimental drugs and/or plant extracts are often dissolved in solvents, including propylene glycol. Nevertheless, there is evidence for psychoactive properties of this alcohol. In this study we found that in the hole-board test 10% propylene glycol did not modify the head-dipping behavior. However, 30% propylene glycol induced an increase in the number of head-dips (46.92 +/- 2.37 compared to 33.83 +/- 4.39, P<0.05, ANOVA/Student-Newman-Keuls), an effect comparable to that obtained with 0.5 mg/kg diazepam (from 33.83 +/- 4.39 to 54 +/- 3.8, P<0.01, ANOVA/Student-Newman-Keuls). These results demonstrate that 30% propylene glycol has significant anxiolytic effects in this model and therefore cannot be used as an innocuous solvent.

Fluorescence quenching of azoalkanes by solvent-assisted radiationless deactivation involving CH bonds

Apparently innocuous solvents such as methylene chloride and chloroform efficiently quench the fluorescence of azoalkane 1 with rate constants of up to 10 8 M −1 s −1 and deuterium effects of ≈ 3.2. This novel fluorescence quenching mechanism by CH bonds is attributed to radiationless deactivation promoted by covalent hydrogen bonding interactions.