Concepts on the contribution of chemistry to a sustainable development. Renewable raw materials

Evaluation of Mechanical Energy Consumption in WPC Production from Pine (Pinus sylvestris) and Hemp (Cannabis sativa L.) with ABS Thermoplastic Additions

This study investigates lignocellulosic biocomposites' physicochemical properties and strength parameters with varying thermoplastic content. Biocomposites were prepared using wood (Pinus sylvestris) or hemp shives (Cannabis sativa L.) combined with 25% and 50% ABS regranulate. The research focused on evaluating the mechanical energy consumption during the compaction of wood-ABS biocomposites with different pine fractions pretreated with hot water extraction (HWE) and analyzing the relationship between strength and thermoplastic content. Results indicate that the composition of the mixture and the size of the hemp shives fraction did not significantly influence energy consumption during densification. Energy values ranged from 1.234 × 10⁻8 J to 8.296 × 10⁻8 J. While the densification of pine after HWE was unsuccessful without ABS, preheating the mixtures with ABS facilitated the production of a uniform composite. The work required for densification ranged from 1.404 × 10⁻5 J to 2.711 × 10⁻5 J for fractions without ABS. For mixtures with ABS, the work required was 1.954 × 10⁻5 J for fraction 0 ÷ 0.4 (f1) and 0.042 × 10⁻5 J for fraction 0.4 ÷ 0.8.

Eco-Friendly and High-Performance Bio-Polyurethane Adhesives from Vegetable Oils: A Review

Current petrochemical-based adhesives adversely affect the environment through substantial volatile organic compound (VOC) emissions during production, contributing to air pollution and climate change. In contrast, vegetable oils extracted from bio-resources provide a compelling alternative owing to their renewability, abundance, and compatibility with adhesive formulation chemistry. This review aimed to critically examine and synthesize the existing scholarly literature on environmentally friendly, sustainable, and high-performance polyurethane adhesives (PUAs) developed from vegetable oils. The use of PUAs derived from vegetable oils promises to provide a long-term replacement while simultaneously maintaining or improving adhesive properties. This quality renders these adhesives appropriate for widespread use in various sectors, including construction, automotive manufacturing, packaging, textile, and footwear industries. This review intended to perform a comprehensive assessment and integration of the existing research, thereby identifying the raw materials, strengths, weaknesses, and gaps in knowledge concerning vegetable oil-based PUAs. In doing so, it responded to these gaps and proposes potential avenues for future research. Therefore, this review accomplishes more than merely evaluating the existing research; it fosters the advancement of greener PUA technologies by identifying areas for improvement and innovation towards more sustainable industrial practices by showcasing vegetable oil-based PUAs as viable, high-performance alternatives to their petroleum-based counterparts.

Life Cycle Assessment of the Sustainability of Alkali-Activated Binders

Limiting the consumption of nonrenewable resources and minimizing waste production and associated gas emissions are the main priority of the construction sector to achieve a sustainable future. This study investigates the sustainability performance of newly developed binders known as alkali-activated binders (AABs). These AABs work satisfactorily in creating and enhancing the concept of greenhouse construction in accordance with sustainability standards. These novel binders are founded on the notion of utilizing ashes from mining and quarrying wastes as raw materials for hazardous and radioactive waste treatment. The life cycle assessment, which depicts material life from the extraction of raw materials through the destruction stage of the structure, is one of the most essential sustainability factors. A recent use for AAB has been created, such as the use of hybrid cement, which is made by combining AAB with ordinary Portland cement (OPC). These binders are a successful answer to a green building alternative if the techniques used to make them do not have an unacceptable negative impact on the environment, human health, or resource depletion. The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) software was employed for choosing the optimal materials' alternative depending on the available criteria. The results revealed that AAB concrete provided a more ecologically friendly alternative than OPC concrete, higher strength for comparable water/binder ratio, and better performance in terms of embodied energy, resistance to freeze-thaw cycles, high temperature resistance, and mass loss due to acid attack and abrasion.

Synthesis design using mass related metrics, environmental metrics, and health metrics

The efforts to integrate environmental aspects, health aspects as well as safety aspects into chemical production has led to the development of measurable and thus objectifying metrics. The application of these metrics is considered to be most promising, especially during the earliest phases of synthesis design. However, the operability in daily work suffers from the lack of available data, or a large variety of data, and the complexity of data processing. If a life cycle assessment is not practical in the early development phase, environmental factor and process mass intensity can give a quick and reliable overview. I will show that this often says the same in advance as a subsequently prepared life cycle assessment. Readers will realise that, based on preparative descriptions, they can quickly determine these metrics for individual syntheses or extensive synthesis sequences applying the available software support. Environmental relevance in terms of persistence, bioaccumulation and toxicity (PBT) can be presented using a modification of the European ranking method ‘DART’ (Decision Analysis by Ranking Techniques). Based on corresponding PBT data, readers can determine a hazard score between 0 and 1 for any substance using the spreadsheet file provided, with which the mass of (potentially emitted) substances can be weighted. Occupational health can be represented using a modification of the recognized ‘Stoffenmanager’. Both concepts are presented and spreadsheet files are offered. This article is based on a presentation which was given at the Green Chemistry Postgraduate Summer School in Venice, 6th–10th July 2020.

Sustainable Oxidation of Cyclohexane and Toluene in the Presence of Affordable Catalysts: Impact of the Tandem of Promoter/Oxidant on Process Efficiency

The oxygenation of cyclohexane and toluene by O₂ and H₂O₂ catalyzed by VO(acac)₂ and Co(acac)₂ was studied at 40-100 °C and 1-10 atm. Upon such conditions, the process can be remarkably (30× times) enhanced by the minute (6-15 mM) additives of oxalic acid (OxalH) or N-hydroxyphthalimide (NHPI). The revealed effect of OxalH on H₂O₂-piloted oxidation is closely associated with the nature of the catalyst cation and boosted by VO(acac)₂. Whereas the effectiveness of Co(acac)₂-based systems was curbed by the addition of OxalH and remained much below the one displayed with the previous system. The observed conspicuous difference in activity was attributed to the substantially higher solubility of in situ formed VO(IV)oxalate compared to that of Co(II)oxalate. The exploration of H₂O₂ for the NHPI-promoted process leads to the decisively lower (5-7 times) yield in comparison to the O₂-driven reaction. Similarly, for the O₂-operated protocol, the yield cannot be improved by addition of OxalH either to VO(acac)₂ + NHPI or to Co(acac)₂ + NHPI mixture. By contrast, the combination of NHPI with VO(acac)₂ or Co(acac)₂ and particularly with the above two mixtures in O₂-piloted oxidation enhances the yield of the aimed products 3-6 times regardless of the substrate used. The revealed significant synergetic effect of the cobalt + vanadyl bicomponent catalyst was due to the participation of each of its moiety in the different stages of the process mechanism. Only benzyl alcohol and benzaldehyde were identified in VO(acac)₂- or Co(acac)₂-catalyzed toluene oxidation, while cyclohexane oxidation yields cyclohexylhydroperoxide in line with cyclohexanol and cyclohexanone. The putative mechanism of investigated processes is highlighted and discussed.

Development of an Innovative and Eco-Friendly UV Radiation Absorber, Based on Furan Moieties

The increasing concern about the environmental impact of ingredients largely used as sunscreens today is pushing research towards new frontiers for the synthesis and degradation potential of innovative sun protection structures. This study deals with the design, synthesis, efficacy evaluation, and environmental impact of new photo-stable molecules at extended electronic conjugation and which have the ‘charge-transfer’ type of optical transition (push and pull). They efficiently perform absorption of electro-magnetic radiation in the UVB and UVA regions. A preliminary screening, dealing with a whole series of aromatic donors, led to the selection of a key substrate derived from waste material, provided with low environmental impact and largely available on the market. As far as the acceptor was concerned, an ester with cyan-acrylic structure and functionalized with aliphatic chains emerged as the most suitable. This allowed a shift of the λ of absorption in the range of the ultraviolet wavelengths. The synthesis procedures include an acid-catalyst-fitted esterification, condensation, and cold crystallization. It was continuously monitored with suitable characterization instruments (GC-MS, 1H NMR, 13C NMR), in order to avoid by-products and parasitic reactions. The resulting structures (patent pending) are composed by a furan core condensed with cyano-acrylic esters, derivatized with branched chains of hydrocarbons of medium length. The obtained structures are capable of good absorption in the range of wavelengths between 300 and 400 nm. Because of their structures, the new molecules are largely soluble in many common oils and cosmetic ingredients. The new molecules have been successively evaluated in terms of photo-stability, biodegradability, compatibility, and UVB-UVA protection capability, both in-vivo and in-vitro, in comparison with existing sunscreens.

Lipid-Based Quaternary Ammonium Sophorolipid Amphiphiles with Antimicrobial and Transfection Activities

Twelve new quaternary ammonium sophorolipids with long alkyl chains on the nitrogen atom were synthesized starting from oleic and petroselinic acid-based sophorolipids. These novel derivatives were evaluated for their antimicrobial activity against selected Gram-negative and Gram-positive bacteria and their transfection efficacies on three different eukaryotic cell lines in vitro as good activities were demonstrated for previously synthesized derivatives. Self-assembly properties were also evaluated. All compounds proved to possess antimicrobial and transfection properties, and trends could be observed based on the length of the nitrogen substituent and the total length of the sophorolipid tail. Moreover, all long-chain quaternary ammonium sophorolipids form micelles, which proved to be a prerequisite to induce antimicrobial activity and transfection capacity. These results are promising for future healthcare applications of long-chained quaternary ammonium sophorolipids.

Simple efficient one-pot synthesis of 5-hydroxymethylfurfural and 2,5-diformylfuran from carbohydrates

A one-pot procedure for the synthesis of DFF starting from mono-, di- or polysaccharides or from primary biomass has been developed. HMF is formed as intermediate and can also be isolated.

H-ZSM-5 Zeolite Synthesis by Sourcing Silica from the Wheat Husk Ash: Characterization and Application as a Versatile Heterogeneous Catalyst in Organic Transformations including Some Multicomponent Reactions

ZSM-5 zeolite was synthesized by sourcing silica from wheat husk ash and was converted into its protonated form following careful, conventionally accepted ion-exchange method and calcinations. The H-ZSM-5 zeolite (Si/Al ratio = 30) prepared was appropriately characterized by XRD, FT-IR, SEM, TEM, TG-DTA, CV, and so forth, and evaluated as recyclable catalyst in selective organic transformations including three- and four-component reactions. The catalytic activity of the zeolite sample supposedly relates to increased density of the accessible acid sites.

Biolubricant basestocks from chemically modified plant oils: ricinoleic acid based-tetraesters

Background

Plant oils have been investigated as a potential source of environmentally favorable biolubricants because of their biodegradability, renewability and excellent lubrication performance. Low oxidation and thermal stability, poor low-temperature properties and a narrow range of available viscosities, however, limit their potential application as industrial lubricants. The inherent problems of plant oils can be improved by attaching functional groups at the sites of unsaturation through chemical modifications. In this article, we will demonstrate how functionalization helps overcome these disadvantages.

Results

In this work, mono-, tri- and tetra-esters have been synthesized, including 10,12-dihydroxy-9-(stearoyloxy)octadecanoic acid 3; 9,10,12-tris(stearoyloxy)octadecanoic acid 4; and 18-(4-ethylhexyloxy)-18-oxooctadecane-7,9,10-triyl tristearate 5. Pour-point and cloud-point measurements have shown that these derivatives have improved low-temperature properties as compared to the precursor. The tetra ester compound, 18-(4-ethylhexyloxy)-18-oxooctadecane-7,9,10-triyl tristearate 5, had the lowest pour point (PP) (−44.37°C) and the lowest cloud point (CP) (−41.25°C). This derivatization also improved the compound’s thermo-oxidative stability, measured using pressurized differential scanning calorimetry (PDSC) and thin-film micro-oxidation (TFMO) testing. 18-(4-Ethylhexyloxy)-18-oxooctadecane-7,9,10-triyl tristearate 5 also had the highest onset temperature (OT) (282.10°C) and the lowest volatile loss and insoluble deposit (37.39% and 50.87%, respectively). Furthermore, the compounds’ tribological behaviors were evaluated using the four-ball method. 18-(4-Ethylhexyloxy)-18-oxooctadecane-7,9,10-triyl tristearate 5 also had the lowest coefficient of friction (μ) (0.44).

Conclusions

The results showed that, in general, these derivatives have good anti-wear and friction-reducing properties at relatively low concentrations under all of the test loads. Overall, the data indicates that these derivatives have significant potential to be used as biolubricant basestocks.

New biobased high functionality polyols and their use in polyurethane coatings

High-functionality polyols for application in polyurethanes (PUs) were prepared by epoxide ring-opening reactions from epoxidized sucrose esters of soybean oil-epoxidized sucrose soyates-in which secondary hydroxyl groups were generated from epoxides on fatty acid chains. Ester polyols were prepared by using a base-catalyzed acid-epoxy reaction with carboxylic acids (e.g., acetic acid); ether polyols were prepared by using an acid-catalyzed alcohol-epoxy reaction with monoalcohols (e.g., methanol). The polyols were characterized by using gel permeation chromatography, FTIR spectroscopy, (1)H NMR spectroscopy, differential scanning calorimetry (DSC), and viscosity measurements. PU thermosets were prepared by using aliphatic polyisocyanates based on isophorone diisocyanate and hexamethylene diisocyanate. The properties of the PUs were studied by performing tensile testing, dynamic mechanical analysis, DSC, and thermogravimetric analysis. The properties of PU coatings on steel substrates were evaluated by using ASTM methods to determine coating hardness, adhesion, solvent resistance, and ductility. Compared to a soy triglyceride polyol, sucrose soyate polyols provide greater hardness and range of cross-link density to PU thermosets because of the unique structure of these macromolecules: well-defined compact structures with a rigid sucrose core coupled with high hydroxyl group functionality.

Lithium salt of tetrahydroxybenzoquinone: toward the development of a sustainable Li-ion battery

The use of lithiated redox organic molecules containing electrochemically active C=O functionalities, such as lithiated oxocarbon salts, is proposed. These represent alternative electrode materials to those used in current Li-ion battery technology that can be synthesized from renewable starting materials. The key material is the tetralithium salt of tetrahydroxybenzoquinone (Li(4)C(6)O(6)), which can be both reduced to Li(2)C(6)O(6) and oxidized to Li(6)C(6)O(6). In addition to being directly synthesized from tetrahydroxybenzoquinone by neutralization at room temperature, we demonstrate that this salt can readily be formed by the thermal disproportionation of Li(2)C(6)O(6) (dilithium rhodizonate phase) under an inert atmosphere. The Li(4)C(6)O(6) compound shows good electrochemical performance vs Li with a sustained reversibility of approximately 200 mAh g(-1) at an average potential of 1.8 V, allowing a Li-ion battery that cycles between Li(2)C(6)O(6) and Li(6)C(6)O(6) to be constructed.

From biomass to a renewable LixC6O6 organic electrode for sustainable Li-ion batteries

Li-ion batteries presently operate on inorganic insertion compounds. The abundance and materials life-cycle costs of such batteries may present issues in the long term with foreseeable large-scale applications. To address the issue of sustainability of electrode materials, a radically different approach from the conventional route has been adopted to develop new organic electrode materials. The oxocarbon salt Li2C6O6 is synthesized through potentially low-cost processes free of toxic solvents and by enlisting the use of natural organic sources (CO2-harvesting entities). It contains carbonyl groups as redox centres and can electrochemically react with four Li ions per formula unit. Such battery processing comes close to both sustainable and green chemistry concepts, which are not currently present in Li-ion cell technology. The consideration of renewable resources in designing electrode materials could potentially enable the realization of green and sustainable batteries within the next decade.

Alcohols as Electrophiles in CC Bond-Forming Reactions: The Hydrogen Autotransfer Process

The hydrogen autotransfer process involves an initial oxidative hydrogen elimination, followed by different types of reactions, and is completed with a reductive hydrogen addition to give the final product. The sequence allows the alkylation of different nucleophilic agents using environmentally benign alcohols as electrophiles, mild conditions, and soft bases, with water produced as the only waste material. Recent examples of modulating the organometallic catalyst have also lent themselves to expansion of the range of available substrates, as described in this Minireview.