Highly Efficient Process for the Conversion of Glycerol to Acrylic Acid via Gas Phase Catalytic Oxidation of an Allyl Alcohol Intermediate

Evaluation of Chemical and Physical Triggers for Enhanced Photosynthetic Glycerol Production in Different Dunaliella Isolates

The salt-tolerant marine microalgae Dunaliella tertiolecta is reported to generate significant amounts of intracellular glycerol as an osmoprotectant under high salt conditions. This study highlights the phylogenetic distribution and comparative glycerol biosynthesis of seven new Dunaliella isolates compared to a D. tertiolecta reference strain. Phylogenetic analysis indicates that all Dunaliella isolates are newly discovered and do not relate to the D. tertiolecta reference. Several studies have identified light color and intensity and salt concentration alone as the most inducing factors impacting glycerol productivity. This study aims to optimize glycerol production by investigating these described factors singularly and in combination to improve the glycerol product titer. Glycerol production data indicate that cultivation with white light of an intensity between 500 and 2000 μmol m-2 s-1 as opposed to 100 μmol m-2 s-1 achieves higher biomass and thereby higher glycerol titers for all our tested Dunaliella strains. Moreover, applying higher light intensity in a cultivation of 1.5 M NaCl and an increase to 3 M NaCl resulted in hyperosmotic stress conditions, providing the highest glycerol titer. Under these optimal light intensity and salt conditions, the glycerol titer of D. tertiolecta could be doubled to 0.79 mg mL-1 in comparison to 100 μmol m-2 s-1 and salt stress to 2 M NaCl, and was higher compared to singularly optimized conditions. Furthermore, under the same conditions, glycerol extracts from new Dunaliella isolates did provide up to 0.94 mg mL-1. This highly pure algae-glycerol obtained under optimal production conditions can find widespread applications, e.g., in the pharmaceutical industry or the production of sustainable carbon fibers.

Perspectives for the Upgrading of Bio-Based Vicinal Diols within the Developing European Bioeconomy

The previous decade has witnessed a drastic increase of European incentives aimed at pushing forward the transition from an exclusively petro-based economy toward a strong and homogeneous bio-based economy. Since 2012, numerous programs have been developed to stimulate and promote research and innovation relying on sustainable and renewable resources. Terrestrial biomass is a virtually infinite reservoir of biomacromolecules, the biorefining of which provides platform molecules of low complexity yet with tremendous industrial potential. Among such bio-based platform molecules, polyols and, more specifically, molecules featuring vicinal diols have gained tremendous interest and have stimulated an increasing research effort from the chemistry and chemical engineering communities. This Review revolves around the most promising process conditions and technologies reported since 2012 that specifically target bio-based vicinal diols and promote their transformation into value-added molecules of wide industrial interest, such as olefins, epoxides, cyclic carbonates, and ketals.

Transition metal-catalyzed deoxydehydration: missing pieces of the puzzle

Deoxydehydration (DODH) is a transformation that converts a vicinal diol into an olefin with the help of a sacrificial reductant.

Multistep batch-flow hybrid synthesis of a terbinafine precursor

A three-step batch-flow hybrid process has been developed for an expeditious synthesis of the enynol key intermediate of antifungal terbinafine. This procedure involves consecutive organometallic steps without the necessity of any in-line purification: after a metalation by n-butyllithium, a selective addition of the lithium salt was elaborated followed by a Grignard reaction resulting in a high yield of 6,6-dimethylhept-1-en-4-yn-3-ol. Moreover, as an alternative to tetrahydrofuran, cyclopentyl methyl ether was used as solvent implementing a safe, sustainable, yet selective synthetic process. Even on a laboratory-scale, the optimized batch-flow hybrid process had a theoretical throughput of 41 g/h. Furthermore, the newly developed process provides an efficient synthesis route to the key-intermediate, while making acrolein obsolete, minimizing side-products, and enabling safe and convenient scale-up.

Advances in catalytic production processes of biomass-derived vinyl monomers

This review provides a summary and perspective for three bio-derived vinyl monomers – acrylic acid, methacrylic acid and styrene.

Polymers Based on Cyclic Carbonates as Trait d'Union Between Polymer Chemistry and Sustainable CO2 Utilization

Given the large amount of anthropogenic CO₂ emissions, it is advantageous to use CO₂ as feedstock for the fabrication of everyday products, such as fuels and materials. An attractive way to use CO₂ in the synthesis of polymers is by the formation of five-membered cyclic organic carbonate monomers (5CCs). The sustainability of this synthetic approach is increased by using scaffolds prepared from renewable resources. Indeed, recent years have seen the rise of various types of carbonate syntheses and applications. 5CC monomers are often polymerized with diamines to yield polyhydroxyurethanes (PHU). Foams are developed from this type of polymers; moreover, the additional hydroxyl groups in PHU, absent in classical polyurethanes, lead to coatings with excellent adhesive properties. Furthermore, carbonate groups in polymers offer the possibility of post-functionalization, such as curing reactions under mild conditions. Finally, the polarity of carbonate groups is remarkably high, so polymers with carbonates side-chains can be used as polymer electrolytes in batteries or as conductive membranes. The target of this Review is to highlight the multiple opportunities offered by polymers prepared from and/or containing 5CCs. Firstly, the preparation of several classes of 5CCs is discussed with special focus on the sustainability of the synthetic routes. Thereafter, specific classes of polymers are discussed for which the use and/or presence of carbonate moieties is crucial to impart the targeted properties (foams, adhesives, polymers for energy applications, and other functional materials).

General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis

In this review paper, we have assembled the main characteristics of partial oxidation reactions (oxidative dehydrogenation and selective oxidation to olefins or oxygenates, as aldehydes and carboxylic acids and nitriles), as well as total oxidation, particularly for depollution, environmental issues and wastewater treatments. Both gas–solid and liquid–solid media have been considered with recent and representative examples within these fields. We have also discussed about their potential and prospective industrial applications. Particular attention has been brought to new raw materials stemming from biomass, as well as to liquid–solid catalysts cases. This review paper also summarizes the progresses made in the use of unconventional activation methods for performing oxidation reactions, highlighting the synergy of these technologies with heterogeneous catalysis. Focus has been centered on both usual catalysts activation methods and less usual ones, such as the use of ultrasounds, microwaves, grinding (mechanochemistry) and photo-activated processes, as well as their combined use.

Highly Selective Synthesis of Acrylic Acid from Lactide in the Liquid Phase

A new reaction system for the highly selective, hydrobromic acid catalyzed conversion of lactide into acrylic acid under mild conditions is reported. The applied liquid reaction system consists of a temperature-stable bromide-containing ionic liquid and 2-bromopropionic acid as a source of dry HBr, with no volatile organic solvent being used. This allows for the in situ removal of the formed acrylic acid, leading to an unmatched acrylic acid selectivity of over 72 % at full lactide conversion. Accounting for leftover reaction intermediates on the way to acrylic acid, which could be recycled in an elaborate continuous process, the proposed reaction system shows potential for acrylic acid yields well above 85 % in the liquid phase. This opens new avenues for the effective conversion of biogenic lactic acid (e.g., obtained by fermentation from starch) to acrylic acid. The resulting bio-acrylic acid is a highly attractive product for, for example, the diaper industry, where we expect consumers to be especially sensitive to aspects of sustainability.

Catalytic Transformation of Cellulose and Its Derivatives into Functionalized Organic Acids

Cellulose is a promising renewable and abundant resource for the production of high-value chemicals, in particular, organic oxygenates, because of its high oxygen/carbon ratio. The sustainable production of hydroxycarboxylic acids and dicarboxylic acids, such as gluconic/glucaric acid, lactic acid, 2,5-furandicarboxylic acid, adipic acid, and terephthalic acid, most of which are monomers of key polymers, have attracted much attention in recent years. The synthesis of these organic acids from cellulose generally involves several tandem reaction steps, and thus, multifunctional catalysts that can catalyze the selective activation of specific C-O or C-C bonds hold the key. This review highlights recent advances in the development of efficient catalytic systems and new strategies for the selective conversion of cellulose or its derived carbohydrates into functionalized organic acids. The reaction mechanism is discussed to offer deep insights into the regioselective cleavage of C-O or C-C bonds.

Bio-based acrylic acid from sugar via propylene glycol and allyl alcohol

Propylene glycol is converted to acrylic acid via dehydration to allyl alcohol. A process flow scheme is proposed, based on distillation resistance.

A Simple and Mild Approach for the Synthesis of p-Xylene from Bio-Based 2,5-Dimethyfuran by Using Metal Triflates

The production of aromatic platform chemicals from biomass-derived feedstocks is of considerable importance in biomass conversion. However, the development of effective routes with simple steps and under mild conditions is still challenging. In this work, we report an original route for the direct synthesis of p-xylene from 2,5-dimethylfuran and acrylic acid catalyzed by scandium(III) triflate (Sc(OTf)₃ ) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim]NTf₂ ) under mild conditions. An overall 63 % selectivity towards p-xylene and 78 % selectivity towards aromatics were obtained at 90 % conversion of 2,5-dimethylfuran by enhancing the dehydration and introducing an extra one-pot decarboxylation step. Furthermore, various dienes and dienophiles were employed as reactants to extend the substrate scope. The aromatic compounds were obtained in moderate yields, which proved the potential of the method to be a generic approach for the conversion of bio-based furanics into renewable aromatics.