Advances of responsive deep eutectic solvents and application in extraction and separation of bioactive compounds

In recent years, it has been found that changing ambient conditions (CO₂/N₂, temperature, pH) can trigger a switchable phase transition of deep eutectic solvents, and such solvents are known as responsive deep eutectic solvents. In this work, we present the development history, properties, and preparation of responsive deep eutectic solvents, followed by the application of responsive deep eutectic solvents in the extraction and separation of bioactive compounds are presented. Importantly, the mechanism of responsive deep eutectic solvents in the extraction of bioactive compounds is discussed. Finally, the challenges and prospects of responsive deep eutectic solvents in the extraction and separation of bioactive compounds are proposed. Responsive deep eutectic solvents are considered green and efficient solvents. Some methods for extraction and separation of bioactive compounds by responsive deep eutectic solvents can increase the possibility of recycling the deep eutectic solvents, and provide higher efficiency in the extraction and separation field. It is hoped that this will provide a reference for the green and sustainable extraction and separation of various bioactive compounds.     

Radical polymerization of methyl methacrylate in the presence of stereoregular poly(methyl methacrylate). IV. Influence of solvent type

Methyl methacrylate (MMA) was polymerized by radical initiation at 25°C or 35°C in various solvents in the presence of stereoregular poly(methyl methacrylate) (PMMA). The occurrence of stereospecific replica polymerization appeared to be related to the capability of stereoassociation of isotactic and syndiotactic PMMA. The solvents can be roughly divided into three types. Type A solvents are polar solvents, which promote stereoassociation resulting in gelation and precipitation. Examples are dimethylformamide, dimethyl sulfoxide, and acetone. Type B solvents are nonpolar aromatic solvents like benzene and toluene, wherein stereoassociation is weaker but still leads to gelation. Type C solvents are very good solvents, in which stereoassociation does not occur. Chloroform and dichloromethane belong to this class. In solvents of type A as well as type B, polymerization in the presence of i-PMMA as a polymer matrix was syndiospecific. However, in the presence of s-PMMA as a polymer matrix the polymerization was isospecific only in type A solvents. The syndiotactic or isotactic triad contents of the polymer formed could be as high as ca. 90% at low conversions. In solvents of type C, polymerization in the presence of stereoregular PMMA proceeds according to a normal radical mechanism. Syndiotacticity was always less than 70%. Stereocomplexes formed in situ during replica polymerization were partly crystalline as detected by x-ray diffraction. The highest crystallinity was detected in those formed in type A solvents.     

A mini review on synthesis,properties and applications of deep eutectic solvents

Organic solvents have been of great importance for many chemical synthesis, storage and separation processes. The industries and research laboratories are heavily dependent on organic solvents in bulk; are highly volatile, lipophilic, toxic and causes a number of issues to the human health and the environmental fitness. Neoteric solvents have been proposed as a better substitute to these harmful organic solvents, and scientists have come up with several neoteric solvents in the last three decades, to name a few: ionic liquids (ILs), switchable solvents, bio-based solvents and deep eutectic solvents (DESs). These neoteric solvents attract a great deal of interest from the scientific community due to plenty of possibilities, therefore, they have huge impact and novel studies are reported quite frequently on the same. In this review, we intend to focus to brief on deep eutectic solvents, about their properties, synthesis, promising applications, and how they gradually emerged from ILs and later stood out as a different class of neoteric solvent, which overcomes many shortcomings of ILs. DESs are possibly receptive synthetic compounds and their relationship based on the hydrogen bond donor or acceptor restricts their reactivity and allow to explore in different disciplines of science.     

Influence of physicochemical properties of solvents on swelling behavior of fluoropolymers

The experimental data are available on the swelling of carbon-black-filled fluorine-containing polymers (Viton) in a number of solvents. However, the quantitative relation between the physicochemical parameters of the solvents and the degree of swelling of the polymers is still unclear. It has been shown that this relation may be determined in terms of the linear free energy concept via solvation of linear equations with due regard for various characteristics of solvents. The polarizability and basicity of solvents are factors governing the degree of polymer swelling. This fact makes it possible to assume the existence of donor-acceptor interaction between fluorine atoms and donor solvents.     

Development of deep eutectic solvents applied in extraction and separation

Deep eutectic solvents, as an alternative to ionic liquids, have greener credentials than ionic liquids, and have attracted considerable attention in related chemical research. Deep eutectic solvents have attracted increasing attention in chemistry for the extraction and separation of various target compounds from natural products. This review highlights the preparation of deep eutectic solvents, unique properties of deep eutectic solvents, and synthesis of deep‐eutectic‐solvent‐based materials. On the other hand, application in the extraction and separation of deep eutectic solvents is also included in this report. In this paper, the available data and references in this field are reviewed to summarize the applications and developments of deep eutectic solvents. Based on the development of deep eutectic solvents, an exploitation of new deep eutectic solvents and deep eutectic solvents‐based materials is expected to diversify into extraction and separation.     

Application of deep eutectic solvents in the extraction and separation of target compounds from various samples

Deep eutectic solvents, as a new type of eco‐friendly solvent, have attracted increasing attention in chemistry for the extraction and separation of target compounds from various samples. To summarize the application of deep eutectic solvents, this review highlights some of the unique properties of deep eutectic solvents and deep‐eutectic‐solvent‐based materials, as well as their applications in extraction and separation. In this paper, the available data and references in this field are reviewed to summarize the application developments of deep eutectic solvents. Based on the development of deep eutectic solvents, the exploitation of new deep eutectic solvents and deep‐eutectic‐solvent‐based materials are expected to diversify into extraction and separation.     

Some aspects of green solvents

Chemical solvents constitute around 80% of the total volume of chemicals used in many important chemical processes, especially fine chemical manufacturing. Unfortunately, these solvents are often volatile organic compounds from petroleum resource bearing several health and environmental risks. Numerous researchers take these two aspects as a reason to search for novel green solvents to replace the conventional ones. As a consequence, there are an increasing number of publications dealing with green solvents. In this review, we discuss the definition and accuracy of the term “green solvent”. We explain our urgent request for application-oriented research in this field. Finally, we point out some promising and interesting kinds of solvents, solvent systems and solubilization concepts for a successful research towards “greener solvents”.     

Potential use of deep eutectic solvents to facilitate lignocellulosic biomass utilization and conversion

High reliance on crude oil for energy consumption results in the urgent need to explore and develop alternative renewable sources. One of the most promising routes is the transformation of biomass into biofuels and chemicals. The introduction of deep eutectic solvents in 2004 received a considerable amount of attention across different research fields, particularly in biomass processing. The effectiveness of deep eutectic solvents in breaking down the recalcitrant structure in biomass highlights its impact on the transformation of biomass into various value-added products. In addition, deep eutectic solvents are widely regarded as promising “green” solvents due to their low cost, low toxicity, and biodegradable properties. In this paper, some background information on lignocellulosic biomass and deep eutectic solvents is given. Furthermore, the roles of deep eutectic solvents in biomass processing are discussed, focusing on the impacts of deep eutectic solvents on the selectivity of chemical processes and dissolution of biomass. This review also highlights the advantages and limitations of deep eutectic solvents associated with their usage in biomass valorization.     

Estimations of excited state dipole moments of conformers in some o-substituted acetophenones by solvato-chromic shifts

Ultra violet absorption spectra of o-methylacetophenone, o-fluoroacetophenone and o-hydroxyacetophenone solutions in different solvents are recorded in the region 200-350 nm at room temperature. Excited state dipole moments for three (pi* <-- pi) transitions of the benzene ring for solutions in non-polar and polar solvents are estimated using solvato-chromic shift method [Delta nu against f(epsilon, n)]. The results show that two types of shifts are observed red and blue shifts. The dipole moment values obtained on excitation by red shifted bands in non-polar solvents are much higher than their counterparts both in the ground state and those of the solutions in polar solvents. Those obtained on excitation by blue shifted bands have lower values than ground state, some with same direction and others of reverse direction in both non-polar and polar solvents.     

在非水介质中进行酶促反应的几个重要问题

介绍了在非水介质中酶促反应的最新进展。较深入地讨论了介质性质对酶的催化活性及立体选择性的影响，有机溶剂中必需水含量对酶催化反应的重要性，描述了非缓冲体系中的盐及其它极性添加剂对酶活性的影响，介绍了在非均相的低共熔体系中进行酶促合成肽的研究。     

有机溶剂对酶催化活性和选择性的影响

有机溶剂中酶的结构与功能与在水中有很大的不同, 通过调整反应介质可系统地改善酶针对目标反应的活性和选择性。重点阐述了溶剂对酶催化反应的活性和选择性的影响及其控制策略, 给出了酶催化选择性的热力学预测模型。     

Effect of solvent composition on free release static coating of capillary columns

Summary Three aspects with respect to the selection of solvents for static coating of capillary columns, i.e. coating speed, occurrence of bumping and solubility of stationary phases are discussed. Hypotheses are proposed in an attempt to explain the observed facts that mixed solvents result in much higher coating speeds than those obtained from pure solvents, that a proper choice of solvents together with a good and uniform deactivitation of the column inner wall is needed to prevent bumping. Stationary phase solubility vs. solvent composition is also briefly discussed.     

Effect of solvent nature on intrinsic viscosity of an ethylene-propylene-dicyclopentadiene copolymer

The hydrodynamic behavior of solutions of the ethyleneópropylene-dicyclopentadiene copolymer in hydrocarbon solvents has been studied. It has been shown that the effects of temperature on the thermodynamic affinities of aromatic and aliphatic solvents for copolymer macromolecules are substantially different. The thermodynamic quality of aromatic solvents relative to the copolymer and the hydrodynamic volume of macromolecular coils increase with temperature; the aliphatic solvents show quite a reverse behavior.     

Determination of impurities in high-purity solvents by neutron activation analysis

The determination of impurities in high-purity solvents, (acetone, isopropanol, trichloroethylene and trichlorotrifluoroethane) used in the production of integrated circuits was carried out by reactor neutron activation analysis. A special vacuum evaporation technique was used for the preconcentration of the solvents. The results showed that sodium and iron are the main impurity components in the solvents and on the other hand the quality of the solvents satisfies the specifications required by high-technology standards. The suspended solid particles in solvents were counted by a Microscopic Image Analysis System (MIAS).     

色谱法筛选C_9芳烃萃取精馏溶剂

将萃取精馏溶剂作为气相色谱固定液,利用气－液色谱法对Ｃ９芳烃所用溶剂进行了选择。共测试环丁砜、邻苯二甲酸二甲酯等７种溶剂。其中邻苯二甲酸二甲酯对Ｃ９芳烃异构体的分离效果较好。方法省时省力,消耗少,结果可靠。     

Kinetics and thermodynamics of the blocking reaction of several aliphatic isocyanates

The oxime-blocking reaction of several aliphatic isocyanates, such as 1,6-Hexane diisocyanate (HDI), isophorone diisocyanate (IPDI), and dicyclohexylmethane-4,4′-diisocyanate (H₁₂MDI), is investigated. The reaction is carried on in various solvents that are divided into two categories: aromatic solvents and oxygen-contained solvents. In situ FT-IR is used to monitor the reaction and show the large difference of solvent and the structure of isocyanate. Kinetic studies indicate that the reaction rate appears faster in aromatic solvents although the polarity of aromatic solvents is lower. Then, thermodynamic parameters of the blocking reaction, such as activation energy (E_a), enthalpy (ΔH*) and entropy (ΔS*), are determined from the Arrhenius and Eyring equations. It is found that activation energy in aromatic solvents is higher, but the reaction rate is much faster, all of which are discussed corresponding to the reaction mechanism.     

Poly(MMA-co-MBA-co-MA-POSS)三元共聚物溶液性质的反气相色谱表征

以20种溶剂作为探针分子,采用反气相色谱技术表征了甲基丙烯酸甲酯-甲基丙烯酸丁酯-甲基丙烯酰氧丙基七环戊基倍半硅氧烷三元共聚物[poly(MMA-co-MBA-co-MA-POSS)]的一系列物理化学性质,并分析了溶剂探针分子与共聚物分子间的相互作用以及共聚物在溶剂中的溶解性.结果表明:在实验温度范围内(343～393K),乙酸甲酯、乙酸乙酯、芳烃、二氯甲烷、三氯甲烷是良溶剂,乙酸丙酯、乙酸丁酯、乙酸戊酯、四氯化碳是中等溶剂,烷烃类和醇类是劣溶剂;随着共聚物中POSS含量的增大,溶剂探针分子溶解聚合物的能力增强,但引入POSS对共聚物的溶度参数无明显影响.     

A New Quaternary Mobile Phase System for Optimization of TLC Separations of Alkaloids Using Mixture Designs and Response Surface Modelling

Abstract

A new combination of four organic solvents is proposed for the optimization of TLC separations of basic drugs and alkaloids. The solvents are diethylamine (DEA), methanol (MeOH), chloroform (CHCl₃) and ethylacetate (EtAc). They were selected from a collection of ten solvents used in Normal Phase TLC mobile phases recommended for the separation of alkaloids and basic drugs in the literature. The selection was based on the classification of solvents according to selectivity and solubility parameters. Excluded were apolar and weak solvents that show no selective (polar) properties and are used only for the adjustment of the solvent strength. Polar solvents from different selectivity groups were selected to combine as many as possible selective effects in one solvent system. The final choice was made considering the displacement theory for Liquid Solid Chromatography.