Application Of Green Solvents Research Articles

Furfural production from biomass residues: Current technologies, challenges and future prospects

Hemicellulose-rich lignocellulosic biomass is an ideal source of carbohydrates to produce furfural commercially. Furfural is recognized as a versatile platform chemical with a bright future in many industries, which can be obtained from the hemicellulose fraction via acid hydrolysis followed by recovery and, lastly purification through a distillation system. This review provides a critical analysis of the recent progress of industrial furfural production from lignocellulosic biomass worldwide. Although old-fashioned process technologies are well established and adopted widely, many novel technologies have emerged to overcome several drawbacks that induce sustainability challenges as well as fully utilize other lignocellulosic components, including cellulose and lignin. Furfural forms the natural precursor for many furan-based derivatives that are vital in the biochemicals and biofuels manufacturing sector, with furfuryl alcohol being the most prominent downstream product. Corn cobs and sugarcane bagasse are the most commonly used raw materials by furfural manufacturing companies on a commercial scale. Furfural market analysis is also performed to study the ongoing economic trends. Techno-economic analyses of furfural production are reviewed to provide insights and strategies on improving furfural production. These topics are reviewed, as well as the future technology development opportunities, including extraction techniques using supercritical fluid, the application of green solvent, and the use of heterogeneous acid catalyst to enhance furfural production.

Biomass delignification with green solvents towards lignin valorisation: ionic liquids vs deep eutectic solvents

The use of renewable resources as feedstocks to ensure the production of goods and commodities for society has been explored in the last decades to switch off the overexploited and pollutant fossil-based economy. Today there is a strong movement to set bioeconomy as priority, but there are still challenges and technical limitations that must be overcome in the first place, particularly on biomass fractionation. For biomass to be an appellative raw material, an efficient and sustainable separation of its major components must be achieved. On the other hand, the technology development for biomass valorisation must follow green chemistry practices towards eco-friendly processes, otherwise no environmental leverage over traditional petrochemical technologies will be acquired. In this context, the application of green solvents, such as ionic liquids (ILs) and deep eutectic solvents (DES), in biomass fractionation is envisaged as promising technology that encompasses not only efficiency and environmental benefits, but also selectivity, which is a crucial demand to undertake cascade processes at biorefinery level. In particular, this article briefly discusses the disruptive achievements upon the application of ILs and DES in biomass delignification step towards an effective and selective separation of lignin from polysaccharides. The different physicochemical properties of these solvents, their interactions with lignin and their delignification capacity will be scrutinized, while some highlights will be given to the important characteristics of isolated lignin fractions for further valorisation. The advantages and disadvantages between ILs and DES in biomass delignification will be contrasted as well along the article.

A holistic review on application of green solvents and replacement study for conventional solvents

The knowledge of green chemistry is instrumental in reducing the harmful and toxicity of the environment. The current environment demands that conventionally used petrochemical solvents should be replaced with the recently developed less harmful and less toxic green solvents. The potential applications of green chemical as solvents are required to study based on the green chemistry principles and the separation of solvents. In this review paper, the application of green chemicals was described for five green solvents such as cyclopentyl methyl ether (CPME), 2-methyl tetrahydrofuran (2-MeTHF), propylene carbonate, 1,3-propanediol, and ethyl lactate. The replacement study of conventional petrochemical solvents with these green solvents was discussed here. Based on the comparative studies, the green chemicals were found to be high potential solvents to replaced tetrahydrofuran (THF), dichloromethane (DCM), 1,4-dioxane, and diethyl ether in chemical industry.

Application of Green Solvents: PEG and scCO2 in the Mono- or Biphasic Catalytic Systems for the Repetitive Batch Coupling of Vinylsilanes with Vinyl Boronates toward 1-Boryl-1-silylethenes.

A new method for the repetitive batch silylative coupling (trans-silylation) of vinylsilanes with vinyl boronates in the presence of Ru(CO)Cl(H)(PCy3)2 immobilized in poly(ethylene glycols) (PEGs) has been developed. Three PEGs (PEG600, PEG2000, and MPEG2000) with different molecular weights and end groups (MW = 600–2000) were tested as solvents and immobilization media, while an aliphatic solvent (n-hexane or n-heptane) or supercritical CO2 was used for product extraction. By applying 2 mol % of the Ru–H catalyst, it was possible to carry out up to 15 complete runs, with the predominant formation of 1-boryl-1-silylethenes. This immobilization strategy permitted for catalyst reuse and obtaining higher TON values (approximately 660–734) compared to the reaction in conventional solvents (∼50). Detailed kinetic studies of the most effective catalytic system were performed to determine catalyst activity and stability. Moreover, the reactions were carried out in an MPEG2000/scCO2 biphasic system, positively influencing the process sustainability.

Efficient access to pyrido[1,2-a]pyrimidines and imidazo[1,2-a]pyridines through Knoevenagel reaction/aza–ene addition/intramolecular cyclization

An expeditious metal-free heteroannulation reaction for pyrido[1,2-a]pyrimidines/imidazo[1,2-a]pyridines was developed in green solvent under mild reaction conditions by using three-component reaction of 2-chloroquinoline-3-carbaldehyde, malononitrile and nitroketen aminals, which obtained from the reaction between 1,1-bis(methylthio)-2-nitroethylene and diamines in green solvent under EtOH reflux conditions. This one-pot strategy is very simple and occurs in two steps. The present sequence is visualized as an environmentally benign process with excellent purity and high yields. An efficient, useful and general procedure for the synthesis of pyrido[1,2-a]pyrimidines/imidazo[1,2-a]pyridines via a one-pot three-component reaction of 2-chloroquinoline-3-carbaldehyde, malononitrile/ethyl 2-cyanoacetate and nitroketen aminals under mild and catalyst-free conditions in excellent yields is described. The major advantages of this protocol are high yields, mild and catalyst-free conditions, short reaction times and application of green solvent.

Simultaneous chromatographic analysis of Sofosbuvir/Ledipasvir in their combined dosage form: an application to green analytical chemistry

Application of green solvents for developing green analytical methodologies has grown dramatically in the past few years. The “more hazardous reagents” are replaced by more “environment-friendly solvents” without affecting method performance. In the present study, two simple and accurate chromatographic methods were developed and validated for determination of the new antiviral combination sofosbuvir (SBR) and ledipasvir (LPV). The first adopted method is high-performance thin-layer chromatography coupled to densitometric determination where silica gel 60 F254 plates were used as the stationary phase. Whereas, the running mobile phase used was toluene: ethanol: ammonia (4:1:0.2, v/v/v). Reversed-phase high-performance liquid chromatography with ultraviolet detection was the second method developed. The column used was Inertsil C18 column (150 × 4.6 mm, 5 μm) and the mobile phase was 20 mM potassium dihydrogen orthophosphate (adjusted to pH = 3 using acetic acid): ethanol (60:40, v/v) with a flow rate of 1.0 mL/min. The detection wavelength for both methods was 265 nm. The validation of both methods was done according to ICH guidelines where both methods were found to be accurate, reproducible, and selective. The linearity range for HPTLC and RP-HPLC methods were 0.8–25.6 and 0.4–12.8 μg/band and 6.0–100.0 and 4.0–80.0 μg/mL for sofosbuvir and ledipasvir, respectively. Comparison of the developed methods was done with reported HPLC method where no significant difference was found.

An efficient one-pot synthesis of highly substituted [1,8]naphthyridin-1-phenyl-1-ethanone derivatives via a four-component reaction

An operationally simple one-pot protocol for the synthesis of highly substituted [1,8]naphthyridin-1-phenyl-1-ethanones dealing with 2-chloroquinoline-3-carbaldehyde and 1-phenyl-2-(1,1,1-triphenyl-λ 5-phosphanylidene)ethan-1-one, 1,1-bis(methylthio)-2-nitroethylene or ketene N,S-acetals, and aromatic/aliphatic amine or diamines under mild and catalyst-free conditions in excellent yields is described. The structures of products were corroborated spectroscopically (IR, 1H- and 13C-NMR, and EI-MS) and by X-ray analysis. An efficient, useful and general procedure for the synthesis of [1,8]naphthyridin-1-phenyl-1-ethanones via a one-pot four-component reaction of 2-chloroquinoline-3-carbaldehyde and 1-phenyl-2-(1,1,1-triphenyl-λ 5-phosphanylidene)ethan-1-one, 1,1-bis(methylthio)-2-nitroethylene or ketene N,S-acetals, and aromatic/aliphatic amine or diamines under mild and catalyst-free conditions in excellent yields is described. The major advantages of this protocol are high yields, mild and catalyst-free conditions, short reaction times, and application of green solvent.

ENVIRONMENTAL FRIENDLY BIO-PESTICIDE ROTENONE EXTRACTED FROM Derris sp.: A REVIEW ON THE EXTRACTION METHOD, TOXICITY AND FIELD EFFECTIVENESS

Bio-pesticides are natural occurring substances that control pest and derived either from plants or microorganism. It play a vital role in coping with adverse effect arise due to massive used of synthetic pesticides and development of insecticide resistance of some insect groups in crop productions. Thus, Derris species from Leguminosae (Fabacea) family is a climbing plant of Southeast Asia that was well known for its environmental friendly bioactive compound is used as one of the effective insecticides. Rotenone was one of the bioactive constituents extracted from Derris plant that was used as agricultural pest control due to its strong paralysis action (knock-down effect) on cold blooded animals. Moreover, it has a lethal mechanism in inhibiting respiratory enzyme of insects and easily degrades which makes it environmental friendly. Extraction of rotenone commonly uses organic solvents as extractant either in non-conventional extraction methods or conventional method. Application of green solvents, ionic liquids as extractant is new approach for rotenone extraction. Indeed environmental friendly bio-pesticides have not been studied thoroughly and several approach and further study are required to produce high quality and environmental friendly bio-pesticides. In addition, biological assay such as “Brine Shrimp (Artemia salina) Lethality” study is also vital in order to determine a preliminary safe exposure limit of extracted rotenone prior to be used as pesticides. For that reason, a review of the environmental friendly bio-pesticide rotenone extracted from Derris sp. is presented herewith. This article reviews the up scaling extraction methods, toxicity and its effectiveness against several moth species such as Spodoptera litura and Plutella xylostella.

Tunable solvents: Shades of green

Research into the synthesis and application of green solvents is a developing field of interest relevant to a variety of chemical manufacturers. Tunable solvents utilising carbon dioxide lend themselves to a reduction in work-up solvent and can help avoid the need for energy intensive solvent recovery options such as distillation. This perspective examines the potential benefits of tunable solvents to the chemical manufacturing industry and the environment. Freed from the usual reliance on distillation, high boiling solvents with an inherently lessened potential to cause air emissions can be used as part of a tunable solvent system. The application of bio-based solvents as tunable reaction media is highlighted as an area for further development.