ZnCl2+Urea,the deep eutectic solvent promoted synthesis of the spirooxindolopyrans and xanthenes through a pseudo-three-component approach

Various spirooxindolopyrans and xanthenes were synthesized efficiently through a pseudo-three-component reaction by using deep eutectic solvent (DES) ZnCl₂+Urea. The remarkable advantages of this reaction are the usage of an environmentally benign solvent (DES), simple purification method, operational simplicity, less reaction time, and higher yields making the reaction a green protocol.     

Deep eutectic solvent-assisted one-pot synthesis of 2-aminothiazole and 2-aminoxazole derivatives

Choline chloride–urea-based deep eutectic solvent (DES) has been found to be a highly effective catalyst and reaction medium for the one-pot synthesis of 2-aminothiazole and 2-aminoxazole derivatives. Three-component reactions of active methylene compounds, urea or thiourea and N-bromosuccinimide NBS in deep eutectic solvent furnished structurally diverse 2-aminoxazoles and 2-aminothiazoles in good to excellent yields under mild reaction conditions and short reaction times. DES is inexpensive, biodegradable and more accessible in any laboratory and industry.     

Choline chloride based eutectic solvent for the efficient synthesis of 2-amino-4H-chromen-4-yl phosphonate derivatives via multicomponent reaction under mild conditions

Synthesis of 2-amino-4H-chromen-4-ylphosphonate derivatives has been accomplished by the one-pot three-component reaction of salicylaldehyde, malononitrile/ethylcyanoacetate and dialkyl phosphites in the presence of reusable deep eutectic solvent (DES) under mild conditions. The advantages of this method are mild reaction conditions, simple work-up procedure, use of DES as a green solvent and an economical protocol for the preparation of important biologically active phosphorus-containing compounds.     

Deep eutectic solvents and glycerol: a simple,environmentally benign and efficient catalyst/reaction media for synthesis of N-aryl phthalimide derivatives

Abstract

Deep eutectic solvents (DES) and glycerol have been successfully employed as efficient catalysts/reaction media in the synthesis of N-aryl phthalimide derivatives from phthalic anhydride and primary aromatic amines. The DES prepared from choline chloride and malonic acid proved to be an efficient catalyst whereas glycerol and the DES of choline chloride and urea played a dual role of catalyst and solvent. These mixtures are biodegradable, nontoxic, and cost-effective thereby providing a good industrial alternative to conventional methods. These methods gave products in moderate to high yields with good recyclability of catalyst/solvent at least up to five consecutive runs.     

An atom-economic and odorless thia-Michael addition in a deep eutectic solvent

The first 100% atom-efficient and odorless protocol for carbon–sulfur bond formation in a deep eutectic solvent (DES) as both the reaction medium and catalyst is reported. The biodegradable and inexpensive DES provides an efficient and convenient ionic reaction medium for the thia-Michael addition with in situ generation of S-alkylisothiouronium salts in place of thiols without the urea by-product segment. This protocol offers several advantages including short reaction times, high yields, clean reactions, and inexpensive and commercially available starting materials.     

A sustainable approach to the Ugi reaction in deep eutectic solvent

The Ugi reaction goes fast with high yields in a recyclable and biodegradable low-melting mixture of choline chloride and urea (DES) as a novel and efficient reaction medium. The DES is applicable to a wide range of aldehydes, amines, isocyanides, and acids in good to excellent isolated yields (60–92%) and short reaction times (2–5 h) and can be reused four times without any loss of activity.     

Human telomere sequence DNA in water-free and high-viscosity solvents: g-quadruplex folding governed by kramers rate theory

Structures formed by human telomere sequence (HTS) DNA are of interest due to the implication of telomeres in the aging process and cancer. We present studies of HTS DNA folding in an anhydrous, high viscosity deep eutectic solvent (DES) comprised of choline choride and urea. In this solvent, the HTS DNA forms a G-quadruplex with the parallel-stranded ("propeller") fold, consistent with observations that reduced water activity favors the parallel fold, whereas alternative folds are favored at high water activity. Surprisingly, adoption of the parallel structure by HTS DNA in the DES, after thermal denaturation and quick cooling to room temperature, requires several months, as opposed to less than 2 min in an aqueous solution. This extended folding time in the DES is, in part, due to HTS DNA becoming kinetically trapped in a folded state that is apparently not accessed in lower viscosity solvents. A comparison of times required for the G-quadruplex to convert from its aqueous-preferred folded state to its parallel fold also reveals a dependence on solvent viscosity that is consistent with Kramers rate theory, which predicts that diffusion-controlled transitions will slow proportionally with solvent friction. These results provide an enhanced view of a G-quadruplex folding funnel and highlight the necessity to consider solvent viscosity in studies of G-quadruplex formation in vitro and in vivo. Additionally, the solvents and analyses presented here should prove valuable for understanding the folding of many other nucleic acids and potentially have applications in DNA-based nanotechnology where time-dependent structures are desired.     

Ultrasound mediated efficient ring opening of epoxides by in situ generated dithiocarbamates in green reaction media

Ultrasound accelerated a safe, clean and environmentally benign one-pot, three-component synthesis of 2-hydroxy dithiocarbamate, from amine, carbon disulfide and epoxide in good to excellent yields and short reaction time with excellent chemo-, regio-, and stereoselectivities in green reaction media (water, deep eutectic solvent [DES] and polyethylene glycol [PEG]). The one-pot, three-component condensation of primary and secondary amine with carbon disulfide and epoxides under ultrasonic irradiation was developed as a green and fast protocol for the rapid high-yielding preparation of 2-hydroxy dithiocarbamate in green reaction media without organic solvent and tedious workup.     

Hydrophobic modification of nanocellulose and all-cellulose composite films using deep eutectic solvent as a reaction medium

Cellulose - In this work, deep eutectic solvent (DES) based on imidazole and triethylmethylammonium chloride was used as a reaction medium for the esterification of cellulose nanofiber (CNF) and...     

深共熔溶剂在有机反应中的应用

深共熔溶剂(DES)作为一种低共熔混合物,由于具有廉价易得、蒸汽压低、无毒性、不易燃、可生物降解、可调控以及易循环使用等优点,逐渐成为一种新型的绿色溶剂或催化剂。本文介绍了DES的组成、分类,重点综述了DES作为溶剂或催化剂应用于常见的加成、取代、偶联、缩合、环化、酯化、多组分及解聚等有机反应。最后展望了DES在有机反应中的发展前景。     

Furfural and 5-Hydroxymethylfurfural Production from Sugar Mixture Using Deep Eutectic Solvent/MIBK System

Choline chloride (ChCl) / glycolic acid (GA) deep eutectic solvent (DES) media with high water content but without any additional catalyst are introduced in furfural and 5-hydroxymethylfurfural (HMF) production. The effects of water content, reaction time, and reaction temperature are investigated with two feedstocks: a glucose/xylose mixture and birch sawdust. Based on the results, 10 equivalent quantities of water (32.9 wt.%) were revealed to be beneficial for conversions without rupturing the DES structure. The optimal reaction conditions were 160 °C and 10 minutes for the sugar mixture and 170 °C and 10 minutes for birch sawdust in a microwave reactor. High furfural yields were achieved, namely 62 % from the sugar mixture and 37.5 % from birch sawdust. HMF yields were low, but since the characterization of the solid residue of sawdust, after DES treatment, was revealed to contain only cellulose (49 %) and lignin (52 %), the treatment could be potentially utilized in a biorefinery concept where the main products are obtained from the cellulose fraction. Extraction of products into the organic phase (methyl isobutyl ketone, MIBK) during the reaction enabled the recycling of the DES phase, and yields remained high for three runs of recycling.     

Application of deep eutectic solvents for the extraction of phenolic compounds from extra-virgin olive oil

A HPLC–DAD/ESI–MS method has been developed and validated for the analysis of the most representative phenolic compounds in extra-virgin olive oil (EVOO) samples using a green extraction approach based on deep eutectic solvents (DESs) at room temperature. We examined ten DESs based on choline chloride and betaine in combination with different hydrogen bond donors comprising six alcohols, two organic acids, and one urea. Five phenolic compounds, belonging to the classes of secoiridoids and phenolic alcohols, were selected for the evaluation of extraction efficiency. A betaine-based DES with glycerol (molar ratio 1:2) was found to be the most effective for extracting phenolic compounds as compared to a conventional solvent. The optimization of the extraction method involved the study of the quantity of water to be added to the DES and evaluation of the sample-to-solvent ratio optimal condition. Thirty percent of water added to DES and sample to solvent ratio 1:1 (w/v) were selected as the best conditions. The chromatographic method was validated by studying LOD, LOQ, intraday and interday retention time precision, and linearity range. Recovery values obtained spiking seed oil sample aliquots with standard compounds at 5 and 100 μg/g concentration were in the range between 75.2% and 98.7%.     

Penetration Process of a Hydrated Deep Eutectic Solvent Through the Stratum Corneum and its Application as a Protein Penetration Enhancer

The penetration mechanism of choline chloride-glycerol deep eutectic solvent (DES) through the stratum corneum (SC) as a potential solvent for a novel enhancer of protein penetration into the skin was investigated in a wide and small angle X-ray diffraction study. We found that DES penetrated through intercellular lipids but not the corneocytes. DES seemed to extract a portion of lipids of the short lamellae in the SC. Hydrated DES with a DES to water weight ratio of 9 to 1 (9DES-1H₂O) showed the strongest interaction with the lipids in the SC compared with water, DES, and hydrated DESs with another weight ratio of DES to water (DES : water=8 : 2). In a skin penetration test with a fluorescently labelled lysozyme, 9DES-1H₂O increased the amount of penetration through the SC by two-fold compared with HEPES buffer.     

Synthesis of 14H-dibenzo xanthene derivatives using choline chloride/tin(II) chloride deep eutectic solvent and Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/ƛ-carrageenan/Zn(II)

In this study, various xanthene derivatives have prepared efficiently through a simple method using choline chloride/tin(II) chloride (ChCl·2SnCl₂) deep eutectic solvent (DES), alone, or in the presence of Fe₃O₄/?-carrageenan/Zn(II) magnetic bionanocatalyst. In the employed procedure, 2-naphthol derivatives have mixed with aromatic or aliphatic aldehydes and the reactions have been completed in the presence of DES at 90 °C in 1.5 h. In addition, using DES/Fe₃O₄/?-carrageenan/Zn(II), the reaction time was reduced to 30 min. The employed DES has been recycled four times without important loss of its activity.     

Carbon-SO3H catalyzed expedient synthesis of new spiro-[indeno[1,2-b]quinoxaline-[11,2′]-thiazolidine]-4′-ones as biologically important scaffold

In this report, we have described a convenient and eco-compatible approach for synthesis of new hybrid spiro[indeno[1,2-b]quinoxaline-[11,2′]-thiazolidine]-4′-ones (4a–k) via multi-component reaction of indeno[1,2-b]quinoxalinone, α-mercaptocarboxylic acids and various types of amines using urea-choline chloride as green deep eutectic solvent and carbon-SO₃H as a solid acid catalyst. This new protocol produces a thiazolidine ring attached to indeno[1,2-b]quinoxaline through spiro carbon in good to excellent yields. The advantages of this protocol are avoidance of toxic and harmful catalyst and solvents further both catalyst and DES were recovered from the reaction mixture quantitatively and reused several times. Synthesized compounds were characterized on the basis of spectral and single crystal X-ray analysis. The prepared catalyst was characterized by FT-IR, SEM, and X-ray diffraction method.     

低共熔混合物体系中合成无定型的磷酸氧钒催化剂及应用

以尿素/氯化胆碱形成的离子型低共熔混合物溶剂作为反应介质,采用离子液体热合成法制备磷酸氧钒材料.傅里叶变换红外光谱(IR)、X射线衍射(XRD)、扫描电子显微镜(SEM)、能量弥散X射线谱(EDS)和氧化还原滴定表征结果表明:该材料为无定型的、混合价态的纳米尺寸钒磷酸盐,因此可暴露更多的活性位,从而提高催化活性.将其用于环己醇氧化反应,研究反应时间、温度、反应物配比等因素对反应的影响,最终使环己酮的选择性及收率分别达到93.5%和51.4%.     

A practical multigram-scale method for the green synthesis of 5-substituted-1H-tetrazoles in deep eutectic solvent

A series of 5-substituted-1H-tetrazoles have been efficiently synthesized in moderate to excellent yields (68–90%) under mild reaction conditions by combining aryl aldehydes, hydroxylamine hydrochloride with sodium azide in the presence of catalytic amount of Cu(OAc)₂ in deep eutectic solvent (DES). The new synthetic method has many advantages, such as high conversion, green reaction medium, easy work-up, low cost, and environment friendly.     

Cellulose nanocrystals from bleached rice straw pulp: acidic deep eutectic solvent versus sulphuric acid hydrolyses

The present work aims to investigate the feasibility of oxalic acid-choline chloride deep eutectic solvent (OA-ChCl DES), which serves as a promising green solvent that utilized in the acidic deep eutectic solvent (DES) hydrolysis. Oxalic acid-choline chloride DES cellulose nanocrystal (OA-ChCl DES CNC) was isolated from the bleached DES treated pulp (BP) through the acidic DES hydrolysis using 1:1 molar ratio of OA-ChCl DES. The functional groups, crystallinity index, morphological structure, particle size, zeta potential, thermal stability and surface chemistry of the OA-ChCl DES CNC were compared with the sulphuric acid cellulose nanocrystal (SA-CNC) that prepared via sulphuric acid hydrolysis. The findings revealed the presence of negatively charged carboxyl groups on OA-ChCl DES CNC surface after the acidic DES hydrolysis. The physicochemical analyses verified that the OA-ChCl DES CNC was in nano-sized range with polydispersity index (PdI) of 0.56, indicating slightly monodispersed nanoparticles. A stable OA-ChCl DES CNC colloidal suspension with zeta potential value of ?52.1?±?5.2 mV was obtained. The OA-ChCl DES CNC outweighed the SA-CNC in term of thermal stability (288 °C) despite having a slightly lower crystallinity index (76.7%). In fact, the OA-ChCl DES CNC with a yield of 55.1% was achieved through the acidic DES hydrolysis, suggesting that the OA-ChCl DES was capable of promoting efficient cleavage of strong hydrogen bonds in BP.

Graphic abstract

     

Fructose dehydration to 5HMF in a green self-catalysed DES composed of N,N-diethylethanolammonium chloride and p-toluenesulfonic acid monohydrate (p-TSA)

Due to the increasing concerns about the availability and accessibility of fossil fuel reserves, and the subsequent effect of using them on climate change, production of green energy has recently become a hot area of interest in the research field. As a renewable energy source, biomass conversion to biofuels has shown a great potential towards green fuel production; particularly fructose conversion to 5-hydroxymethylfurfural (5HMF) as a building block material and source of green fuels and other high value chemicals.Herein, we investigate fructose dehydration to 5-hydroxymethylfurfural (5HMF) as a green fuel precursor, using a green self-catalysed environmentally friendly Deep Eutectic Solvent (DES), composed of inexpensive N,N-diethylethanolammonium chloride as organic salt and p-toluenesulfonic acid monohydrate (p-TSA) as a hydrogen bond donor (HBD) and novel medium for the fructose dehydration reaction.The advantage of using this DES is its ability to act as a solvent and catalyst simultaneously. It has shown to actively catalyse the dehydration reaction of fructose under moderate reaction conditions with a high 5HMF yield of 84.8% at a reaction temperature of 80 °C, reaction time of 1 h, DES mixing ratio of 1:0.5 salt to p-TSA (w/w), and initial fructose ratio of 5.     

Copper underpotential deposition at gold surfaces in contact with a deep eutectic solvent: New insights

The electrodeposition of copper on a polycrystalline gold electrode and on Au(hkl) single crystals was investigated in a deep eutectic solvent (DES). The DES employed consisted of a mixture of choline chloride and urea (1:2). The Au(hkl)/DES interface was studied using cyclic voltammetry in the capacitive region. The blank voltammograms showed characteristic features, not previously reported, that demonstrate the surface sensitivity of this solvent. Copper electrodeposition was then studied and it was found that this takes place through the formation of an underpotential deposition (UPD) adlayer, demonstrating the surface sensitivity of this process. Voltammetric profiles showed similarities with those obtained in aqueous solutions containing chloride, suggesting that the copper UPD in this DES is strongly influenced by the presence of chloride.