Review

23 pages, 6890 KiB

Open AccessReview

Appealing Renewable Materials in Green Chemistry

by Federico Casti, Francesco Basoccu, Rita Mocci, Lidia De Luca, Andrea Porcheddu and Federico Cuccu

Molecules 2022, 27(6), 1988; https://doi.org/10.3390/molecules27061988 - 19 Mar 2022

Cited by 11 | Viewed by 3364

Abstract

In just a few years, chemists have significantly changed their approach to the synthesis of organic molecules in the laboratory and industry. Researchers are encouraged to approach “greener” reagents, solvents, and methodologies, to go hand in hand with the world’s environmental matter, such [...] Read more.

In just a few years, chemists have significantly changed their approach to the synthesis of organic molecules in the laboratory and industry. Researchers are encouraged to approach “greener” reagents, solvents, and methodologies, to go hand in hand with the world’s environmental matter, such as water, soil, and air pollution. The employment of plant and animal derivates that are commonly regarded as “waste material” has paved the way for the development of new green strategies. In this review, the most important innovations in this field have been highlighted, paying due attention to those materials that have played a crucial role in organic reactions: wool, silk, and feather. Moreover, we decided to focus on the other most important supports and catalysts in green syntheses, such as proteins and their derivates. Different materials have shown prominent activity in the adsorption of metals and organic dyes, which has constituted a relevant scope in the last two decades. We intend to furnish a complete screening of the application given to these materials and contribute to their potential future utilization. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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36 pages, 12207 KiB

Open AccessReview

“Green Is the Color”: An Update on Ecofriendly Aspects of Organoselenium Chemistry

by Juliano B. Azeredo, Filipe Penteado, Vanessa Nascimento, Luca Sancineto, Antonio L. Braga, Eder João Lenardao and Claudio Santi

Molecules 2022, 27(5), 1597; https://doi.org/10.3390/molecules27051597 - 28 Feb 2022

Cited by 28 | Viewed by 3618

Abstract

Organoselenium compounds have been successfully applied in biological, medicinal and material sciences, as well as a powerful tool for modern organic synthesis, attracting the attention of the scientific community. This great success is mainly due to the breaking of paradigm demonstrated by innumerous [...] Read more.

Organoselenium compounds have been successfully applied in biological, medicinal and material sciences, as well as a powerful tool for modern organic synthesis, attracting the attention of the scientific community. This great success is mainly due to the breaking of paradigm demonstrated by innumerous works, that the selenium compounds were toxic and would have a potential impact on the environment. In this update review, we highlight the relevance of these compounds in several fields of research as well as the possibility to synthesize them through more environmentally sustainable methodologies, involving catalytic processes, flow chemistry, electrosynthesis, as well as by the use of alternative energy sources, including mechanochemical, photochemistry, sonochemical and microwave irradiation. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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41 pages, 4817 KiB

Open AccessFeature PaperReview

Recovery Techniques Enabling Circular Chemistry from Wastewater

by Vahideh Elhami, Evelyn C. Antunes, Hardy Temmink and Boelo Schuur

Molecules 2022, 27(4), 1389; https://doi.org/10.3390/molecules27041389 - 18 Feb 2022

Cited by 11 | Viewed by 3453

Abstract

In an era where it becomes less and less accepted to just send waste to landfills and release wastewater into the environment without treatment, numerous initiatives are pursued to facilitate chemical production from waste. This includes microbial conversions of waste in digesters, and [...] Read more.

In an era where it becomes less and less accepted to just send waste to landfills and release wastewater into the environment without treatment, numerous initiatives are pursued to facilitate chemical production from waste. This includes microbial conversions of waste in digesters, and with this type of approach, a variety of chemicals can be produced. Typical for digestion systems is that the products are present only in (very) dilute amounts. For such productions to be technically and economically interesting to pursue, it is of key importance that effective product recovery strategies are being developed. In this review, we focus on the recovery of biologically produced carboxylic acids, including volatile fatty acids (VFAs), medium-chain carboxylic acids (MCCAs), long-chain dicarboxylic acids (LCDAs) being directly produced by microorganisms, and indirectly produced unsaturated short-chain acids (USCA), as well as polymers. Key recovery techniques for carboxylic acids in solution include liquid-liquid extraction, adsorption, and membrane separations. The route toward USCA is discussed, including their production by thermal treatment of intracellular polyhydroxyalkanoates (PHA) polymers and the downstream separations. Polymers included in this review are extracellular polymeric substances (EPS). Strategies for fractionation of the different fractions of EPS are discussed, aiming at the valorization of both polysaccharides and proteins. It is concluded that several separation strategies have the potential to further develop the wastewater valorization chains. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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17 pages, 1946 KiB

Open AccessReview

State of the Art on Green Route Synthesis of Gold/Silver Bimetallic Nanoparticles

by Angela Scala, Giulia Neri, Nicola Micale, Massimiliano Cordaro and Anna Piperno

Molecules 2022, 27(3), 1134; https://doi.org/10.3390/molecules27031134 - 08 Feb 2022

Cited by 15 | Viewed by 2932

Abstract

Recently, bimetallic nanoparticles (BMNPs) blending the properties of two metals in one nanostructured system have generated enormous interest due to their potential applications in various fields including biosensing, imaging, nanomedicine, and catalysis. BMNPs have been developed later with respect to the monometallic nanoparticles [...] Read more.

Recently, bimetallic nanoparticles (BMNPs) blending the properties of two metals in one nanostructured system have generated enormous interest due to their potential applications in various fields including biosensing, imaging, nanomedicine, and catalysis. BMNPs have been developed later with respect to the monometallic nanoparticles (MNPs) and their physicochemical and biological properties have not yet been comprehensively explored. The manuscript aims at collecting the main design criteria used to synthetize BMNPs focusing on green route synthesis. The influence of experimental parameters such as temperature, time, reagent concentrations, capping agents on the particle growth and colloidal stability are examined. Finally, an overview of their nanotechnological applications and biological profile are presented. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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20 pages, 11243 KiB

Open AccessFeature PaperReview

Deep Eutectic Solvents in Solar Energy Technologies

by Chiara Liliana Boldrini, Andrea Francesca Quivelli, Norberto Manfredi, Vito Capriati and Alessandro Abbotto

Molecules 2022, 27(3), 709; https://doi.org/10.3390/molecules27030709 - 21 Jan 2022

Cited by 25 | Viewed by 3262

Abstract

Deep Eutectic Solvents (DESs) have been widely used in many fields to exploit their ecofriendly characteristics, from green synthetic procedures to environmentally benign industrial methods. In contrast, their application in emerging solar technologies, where the abundant and clean solar energy is used to [...] Read more.

Deep Eutectic Solvents (DESs) have been widely used in many fields to exploit their ecofriendly characteristics, from green synthetic procedures to environmentally benign industrial methods. In contrast, their application in emerging solar technologies, where the abundant and clean solar energy is used to properly respond to most important societal needs, is still relatively scarce. This represents a strong limitation since many solar devices make use of polluting or toxic components, thus seriously hampering their eco-friendly nature. Herein, we review the literature, mainly published in the last few years, on the use of DESs in representative solar technologies, from solar plants to last generation photovoltaics, featuring not only their passive role as green solvents, but also their active behavior arising from their peculiar chemical nature. This collection highlights the increasing and valuable role played by DESs in solar technologies, in the fulfillment of green chemistry requirements and for performance enhancement, in particular in terms of long-term temporal stability. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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18 pages, 38662 KiB

Open AccessReview

Electrochemical Organic Synthesis of Electron-Rich Biaryl Scaffolds: An Update

by Fabrizio Medici, Simonetta Resta, Alessandra Puglisi, Sergio Rossi, Laura Raimondi and Maurizio Benaglia

Molecules 2021, 26(22), 6968; https://doi.org/10.3390/molecules26226968 - 18 Nov 2021

Cited by 5 | Viewed by 2276

Abstract

Biaryl scaffolds are widely spread in biologically important natural products, in numerous therapeutic agents, but they are also considered a privileged class of ligands and (organo)catalysts; therefore, the development of efficient alternative methodologies to prepare such compounds is always attracting much attention. The [...] Read more.

Biaryl scaffolds are widely spread in biologically important natural products, in numerous therapeutic agents, but they are also considered a privileged class of ligands and (organo)catalysts; therefore, the development of efficient alternative methodologies to prepare such compounds is always attracting much attention. The present review discusses the organic electrosynthesis of biaryls starting from phenols, anilines, naphthols, and naphthylamines. The most significant examples of the works reported in the last decade are presented and classified according to the single class of molecules: after the introduction, the first three sections relate to the reactions of phenols, naphthols, and anilines, respectively; the other two sections refer to cross-coupling and miscellaneous reactions. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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15 pages, 3256 KiB

Open AccessReview

Metal Nanoparticles as Sustainable Tools for C–N Bond Formation via C–H Activation

by Federica Valentini, Oriana Piermatti and Luigi Vaccaro

Molecules 2021, 26(13), 4106; https://doi.org/10.3390/molecules26134106 - 05 Jul 2021

Cited by 7 | Viewed by 2681

Abstract

The design of highly active metal nanoparticles to be employed as efficient heterogeneous catalysts is a key tool for the construction of complex organic molecules and the minimization of their environmental costs. The formation of novel C–N bonds via C–H activation is an [...] Read more.

The design of highly active metal nanoparticles to be employed as efficient heterogeneous catalysts is a key tool for the construction of complex organic molecules and the minimization of their environmental costs. The formation of novel C–N bonds via C–H activation is an effective atom-economical strategy to access high value materials in pharmaceuticals, polymers, and natural product production. In this contribution, the literature of the last ten years on the use of metal nanoparticles in the processes involving direct C–N bond formation will be discussed. Where possible, a discussion on the role and influence of the support used for the immobilization and/or the metal chosen is reported. Particular attention was given to the description of the experiments performed to elucidate the active mechanism. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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19 pages, 37093 KiB

Open AccessReview

Seaweed Polysaccharide Based Products and Materials: An Assessment on Their Production from a Sustainability Point of View

by Nishith A. Chudasama, Rosy Alphons Sequeira, Kinjal Moradiya and Kamalesh Prasad

Molecules 2021, 26(9), 2608; https://doi.org/10.3390/molecules26092608 - 29 Apr 2021

Cited by 39 | Viewed by 7341

Abstract

Among the various natural polymers, polysaccharides are one of the oldest biopolymers present on the Earth. They play a very crucial role in the survival of both animals and plants. Due to the presence of hydroxyl functional groups in most of the polysaccharides, [...] Read more.

Among the various natural polymers, polysaccharides are one of the oldest biopolymers present on the Earth. They play a very crucial role in the survival of both animals and plants. Due to the presence of hydroxyl functional groups in most of the polysaccharides, it is easy to prepare their chemical derivatives. Several polysaccharide derivatives are widely used in a number of industrial applications. The polysaccharides such as cellulose, starch, chitosan, etc., have several applications but due to some distinguished characteristic properties, seaweed polysaccharides are preferred in a number of applications. This review covers published literature on the seaweed polysaccharides, their origin, and extraction from seaweeds, application, and chemical modification. Derivatization of the polysaccharides to impart new functionalities by chemical modification such as esterification, amidation, amination, C-N bond formation, sulphation, acetylation, phosphorylation, and graft copolymerization is discussed. The suitability of extraction of seaweed polysaccharides such as agar, carrageenan, and alginate using ionic solvent systems from a sustainability point of view and future prospects for efficient extraction and functionalization of seaweed polysaccharides is also included in this review article. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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32 pages, 1527 KiB

Open AccessReview

The Role of Hydrogen Bond Donor on the Extraction of Phenolic Compounds from Natural Matrices Using Deep Eutectic Systems

by Duarte Rente, Alexandre Paiva and Ana Rita Duarte

Molecules 2021, 26(8), 2336; https://doi.org/10.3390/molecules26082336 - 17 Apr 2021

Cited by 30 | Viewed by 3368

Abstract

Recently, deep eutectic systems (DESs) as extraction techniques for bioactive compounds have surfaced as a greener alternative to common organic solvents. In order to study the effect of these systems on the extraction of phenolic compounds from different natural sources, a comprehensive review [...] Read more.

Recently, deep eutectic systems (DESs) as extraction techniques for bioactive compounds have surfaced as a greener alternative to common organic solvents. In order to study the effect of these systems on the extraction of phenolic compounds from different natural sources, a comprehensive review of the state of the art was carried out. In a first approach, the addition of water to these systems and its effect on DES physicochemical properties such as polarity, viscosity, and acidity was investigated. This review studied the effect of the hydrogen bond donor (HBD) on the nature of the extracted phenolics. The effects of the nature of the HBD, namely carbon chain length as well as the number of hydroxyl, methyl, and carbonyl groups, have shown to play a critical role in the extraction of different phenolic compounds. This review highlights the differences between DES systems and systematizes the results published in the literature, so that a more comprehensive evaluation of the systems can be carried out before any experimental trial. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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13 pages, 547 KiB

Open AccessReview

Overcoming the Biological Contamination in Microalgae and Cyanobacteria Mass Cultivations for Photosynthetic Biofuel Production

by Zhi Zhu, Jihong Jiang and Yun Fa

Molecules 2020, 25(22), 5220; https://doi.org/10.3390/molecules25225220 - 10 Nov 2020

Cited by 49 | Viewed by 5176

Abstract

Microalgae and cyanobacteria have shown significant potential for the development of the next biofuels innovation because of their own characteristics as photosynthetic microorganisms. However, it is confronted with a lot of severe challenges on the economic scaling-up of the microalgae- and cyanobacteria-based biofuels [...] Read more.

Microalgae and cyanobacteria have shown significant potential for the development of the next biofuels innovation because of their own characteristics as photosynthetic microorganisms. However, it is confronted with a lot of severe challenges on the economic scaling-up of the microalgae- and cyanobacteria-based biofuels production. One of these major challenges is the lack of a reliable preventing and controlling culture system of biological contamination, which can attack the cell growth or product accumulation causing crashing effects. To increase the commercial viability of microalgae- and cyanobacteria-based biofuels production, overcoming the biological contaminations should be at the top of the priority list. Here, we highlight the importance of two categories of biological contaminations and their controlling strategies in the mass cultivations of microalgae and cyanobacteria, and outline the directions that should be exploited in the future. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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40 pages, 11873 KiB

Open AccessFeature PaperReview

Chitosan: A Natural Biopolymer with a Wide and Varied Range of Applications

by Carmen P. Jiménez-Gómez and Juan Antonio Cecilia

Molecules 2020, 25(17), 3981; https://doi.org/10.3390/molecules25173981 - 01 Sep 2020

Cited by 249 | Viewed by 13008

Abstract

Although chitin is of the most available biopolymers on Earth its uses and applications are limited due to its low solubility. The deacetylation of chitin leads to chitosan. This biopolymer, composed of randomly distributed β-(1-4)-linked D-units, has better physicochemical properties due to the [...] Read more.

Although chitin is of the most available biopolymers on Earth its uses and applications are limited due to its low solubility. The deacetylation of chitin leads to chitosan. This biopolymer, composed of randomly distributed β-(1-4)-linked D-units, has better physicochemical properties due to the facts that it is possible to dissolve this biopolymer under acidic conditions, it can adopt several conformations or structures and it can be functionalized with a wide range of functional groups to modulate its superficial composition to a specific application. Chitosan is considered a highly biocompatible biopolymer due to its biodegradability, bioadhesivity and bioactivity in such a way this biopolymer displays a wide range of applications. Thus, chitosan is a promising biopolymer for numerous applications in the biomedical field (skin, bone, tissue engineering, artificial kidneys, nerves, livers, wound healing). This biopolymer is also employed to trap both organic compounds and dyes or for the selective separation of binary mixtures. In addition, chitosan can also be used as catalyst or can be used as starting molecule to obtain high added value products. Considering these premises, this review is focused on the structure and modification of chitosan as well as its uses and applications. Full article

(This article belongs to the Special Issue Review Papers in Green Chemistry)

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