Methyl Lactate Research Articles

Simultaneous strengthening and toughening of PLA with full recyclability enabled by resin-microsphere-modified L-lactide oligomers

Various strategies have been developed to improve the brittleness of poly (lactic acid) (PLA), most of which still suffer from the toughness-strength trade-off dilemma. Herein, we prepared phenol–formaldehyde-resin microspheres (PFM) with aliphatic hydroxyl groups to initiate L-lactide polymerization and synthesized a series of PFM-modified L-lactide oligomers (PFM-OLLA) bearing different arm lengths. PFM-OLLA were then physically blended with commercial PLA in different weight ratios to prepare synchronously strengthened and toughened PFM-OLLA/PLA composites. After blending with 4 % PFM2.5-OLLA (PFM content: 2.5 %), the mechanical properties of the PFM2.5-OLLA/PLA composites were best. PFM2.5-OLLA efficiently improved the crystallization behaviors of the PFM2.5-OLLA/PLA composites, thereby significantly enhancing their strength and toughness. The maximum tensile yield strength (40.2 MPa), elongation at break (85.7 %), and impact strength (20.8 kJ/m2) of PFM2.5-OLLA/PLA composites could respectively increase by 44.2 %, 465.7 %, and 100 %, compared to the values of neat PLA. The microscopic strengthening and toughening mechanisms were attributed to the rigidity of PFM, and the heterogeneous nucleating ability as well as larger free volume of PFM2.5-OLLA, whereas the visual toughening effects were attributed to multiple crazing and shear yielding phenomena. After simple alcoholysis and filtration, the polymer components were completely converted into methyl lactate. The recycled PFM, exhibiting excellent chemical stability, were reused to synthesize a new PFM-OLLA for strengthening and toughening PLA. This study provides a sustainable strategy for the development of high-performance PLA engineering materials showing great application potentials in the automotive, electronics and housing fields.

Unraveling the Dual Anti-inflammatory and Antioxidant Mechanisms of Acteoside: Computational Insights and Experimental Validation.

Acteoside (ACT) is one of the primary bioactive ingredients in Cistanche tubulosa (Schenk). Its remarkable efficacy in treating immune-related and inflammatory disorders has garnered significant interest among scientific circles. However, the anti-inflammatory and antioxidant effects of ACT and its underlying molecular mechanisms require further investigation. In this study, pharmacophore-based reverse docking and molecular dynamics simulations identified potential anti-inflammatory targets in silico. Studies conducted in vitro with lipopolysaccharide (LPS)-induced RAW264.7 cells validated the anti-inflammatory properties of ACT. Methyl thiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) assays indicated ACT's non-toxic and growth-promoting effects on cells. ACT significantly reduced nitric oxide (NO) and reactive oxygen species (ROS) production and restored levels of antioxidant enzymes. It also decreased pro-inflammatory cytokines. Western blotting assays indicated that ACT inhibited p38, TNF-α, PI3K/AKT, and NF-κB signaling pathways. These findings underscore ACT's ability to mitigate acute inflammation in RAW264.7 cells by modulating key signaling pathways and provide the scientific basis for enhancing the medicinal value of ACT and future drug development.

Zinc {ONO} complexes for the chemical recycling of PET and PLA

Nine {ONO} ligands were prepared and treated with ZnEt2 to form a range of complexes. The resulting complexes were characterised in solution through 1H and 13C{1H} NMR spectroscopy, and in the solid state through single-crystal XRD and elemental analysis. Moderate reactivity towards lactide polymerisation was demonstrated, with hydroxyl complexes reaching high conversion in 1–2 minutes at 300: 1: 1. All complexes successfully degraded PLA to methyl lactate and the effect of reaction time, temperature and catalyst loading was explored. Zn(4)2 successfully produced ethyl and n-butyl lactate and was shown to work in ambient conditions, albeit with reduced yield and selectivity. The production of BHET from waste PET was demonstrated with a selection of the most active catalysts. Zn(4)2 was shown to be capable of sequential PLA/PET degradation and to be tolerant of HDPE/PVC contaminants.

Catalytic recycling of polylactic acid over zirconium phosphate supported WOx active sites

Chemical upcycling of end-of-life plastics is an economically and environmentally feasible way to tackle plastics crisis. Among them, methanol alcoholysis of polylactic acid (PLA) is a promising approach, which can produce methyl lactate (MLA) that can be further converted to lactide to achieve a sustainable development. In this work, a series of WOx/ZrP catalysts with WOx active sites in low coverage and high surface area were synthesized via anchoring WOx species on the surface of zirconium phosphate (ZrP). Characterizations indicated that the strong interaction between WOx and ZrP promoted the formation of WOx active sites in low coverage. In particular, 10 %WOx/ZrP catalyst was highly active and stable for the alcoholysis of PLA plastics under mild conditions due to the abundant WOx active sites and strong acidity. The yield of MLA over 10 %WOx/ZrP catalyst reached 94.5 % within 4 h at 160 °C, which was superior to the performance of traditional solid acids (α-ZrP, HZSM-5, Hβ and Amberlyst-45). In addition, 10 %WOx/ZrP was versatile for the alcoholysis of discarded PLA-based products and could be recycled at least five times. The prominent performance of 10 %WOx/ZrP catalyst and the possible reaction mechanism were discussed.

New reaction pathways for high selectivity synthesis of methyl lactate via SnClx(OH)2-x-catalyzed cellulose conversion in water-containing methanol solution

Catalytic conversion of cellulose into lactic acid (LA) is paramount for the emerging biomass-based chemical industry. With emphasis on the reaction mechanism, the catalytic cellulose conversion to methyl lactate (ML) was systematically investigated in water-containing methanol solution. The role that water plays and catalytic mechanism of the acidic and basic sites were analyzed and discussed. It was found that water played an important role in modulating hydrolysis of SnCl2 to release H+ protons and basic SnClx(OH)2-x species. These basic species are very efficient for the isomerization and [3+3] retro aldol condensation in terminal glucose units of cellulose chain, while H+ protons facilitate the ring-opening of the ends of cellulose chains to trioses rather than hydrolysis of the glucoside bonds to form glucose. Based on advanced characterization techniques including ESI-MS, GPC, FT-IR, XRD, XPS and CP-MAS 13C NMR as well as DFT calculations, two new reaction pathways were disclosed for the first time, which are distinct from the well-known traditional pathway that goes through the formation of glucose. Owing to the exclusion of the formation of glucose during the cellulose conversion, the selectivity towards ML can be greatly enhanced. Under optimal conditions, the total selectivity could reach to 91.5 % with a ML and LA yield of 66.3 %. These findings provide new insights into the catalytic conversion of cellulose into value-added chemicals and help explore effective catalysts.

Conversion of sugars into methyl lactate over poly (ionic liquid)s functionalized Sn/beta zeolites

Methyl lactate (MLA) is a versatile high value platform chemical prepared from biomass carbohydrates, with widely application in the pharmaceutical, food, pesticide, and cosmetics. The current study presented a one-pot catalytic conversion of sugars to MLA over poly (ionic liquid)s functionalized Sn/Beta zeolites under mild conditions. The Sn/Beta zeolites were prepared by an impregnation method, followed by modification with poly (vinyl imidazole) ([PVIM]) via an in-situ free radical polymerization method. Dosages of polymer and Sn, calcination temperature, reaction temperature, catalyst amount, substrate concentration, and reaction times were optimized. Results showed that an MLA yield of 61.4 % was obtained over 3[PVIM]-Sn/Beta with complete conversion of fructose at 140 °C for 8 h. The physicochemical properties were characterized by XRD, BET, FTIR, CO-DRIFTS, NH3-TPD and pyridine-FTIR analysis, indicating the coexistence of Lewis and Brønsted acid sites. Finally, a possible reaction mechanism was proposed that the weak Lewis acidity of imidazole rings of [PVIM] effectively regulated the local microenvironment of active sites, thus promoting the interaction of the active sites with electronegative oxygens of sugars. This study can provide as a reference for the development of solid acid catalysts for the catalytic conversion of biomass to platform chemicals.

Sustainable fabrication of solvent resistant biodegradable cellulose membranes using green solvents

The paradigm of the polymer industry is confronting an inevitable transition from fossil-based to bio-derived sources. The membrane-based separation process, generally regarded as a sustainable technology, mostly employs fossil-based polymeric membranes. In order to become an entirely carbon–neutral technology, all of the materials and chemicals employed during membrane fabrication must be scrutinized from a sustainability perspective. In this work, we report a versatile strategy to fabricate solvent-resistant cellulose membranes using bio-derived green solvents. The thermodynamic and kinetic aspects of the membrane fabrication process were systematically investigated. It was found that well-known green solvents such as Cyrene and PolarClean were not suitable due to high dope viscosity, whereas bio-derived methyl lactate and triethyl phosphate exhibited desirable properties to yield excellent cellulose membranes. The membrane performance could be tailored from the ultrafiltration to nanofiltration range by controlling the fabrication parameters. Importantly, the thermal treatment step prior to the deacetylation reaction was necessary to improve the solute rejection profile. The cellulose membranes displayed adequate compression resistance against pressure. However, their shear resistance was insufficient compared to that of commercial membranes. Nevertheless, the prepared cellulose membranes exhibited excellent solvent resistance in strong aprotic solvents such as N-methylpyrrolidone and N,N-dimethylacetamide, potentially allowing them to enter niche membrane markets such as the organic solvent nanofiltration (OSN).

Exploring green solvents for the sustainable fabrication of bio-based polylactic acid membranes using nonsolvent-induced phase separation

Green and sustainable membrane technology has recently gained attention from the membrane community to minimize the negative environmental impacts associated with conventional membrane production in industries, which rely on petrochemical engineering plastics and toxic organic solvents. While the fabrication of biobased and biodegradable polymeric membranes using common organic solvents has been reported, eco-friendly membrane-fabrication techniques using greener solvents are required to improve sustainability and reduce the negative environmental impact of the membrane industry. For the first time, this study comprehensively investigates the potential use of green solvents for preparing polylactic acid (PLA) membranes via the phase separation technique. PLA solubility and phase separation experiments, employing various green solvents were conducted to examine the potential applicability of these solvents for membrane fabrication. Porous PLA membranes exhibit different surface and pore structures depending on the thermodynamic and kinetic parameters of the green solvents. Based on the phase separation study, both fine PLA ultrafiltration membranes with controllable molecular weight cut-off and mechanically robust PLA microfiltration membranes with bi-continuous pore structure were successfully prepared using methyl lactate. The prepared green membranes showed a competitive filtration performance implying that the fully bio-based PLA membranes could substitute the conventional engineering plastic-based membranes in versatile membrane filtration and separation processes, especially single-use or consumable membrane products in environmental and healthcare industries.

Solvent-controlled assembly of helical coordination polymers based on lactate synthon from two-dimensional layer to three-dimensional framework

Compound (R)-4-(1-carboxyethoxy)-2-methylbenzoic acid ((R)-H2cma) was prepared from (S)-methyl lactate and 4-hydroxy-2-methylbenzoic acid. (R)-H2cma as chiral synthon assembled with 1,3-di(pyridin-4-yl)propane (1,3-dpp) and Ni2+ ions to obtain helical chiral complexes {[Ni2((R)-cma)2(1.3-dpp)2]·H2O}n (HU18-R) and {[Ni2((R)-cma)2(1.3-dpp)2(H2O)]·3H2O}n (HU19-R) in different solvent systems. Single crystal tests revealed that HU18-R is a two-dimensional (2D) structure with two independent Ni2+ centers and HU19-R is a three-dimensional (3D) framework containing dinuclear [Ni2(CO2)2(H2O)]2+ clusters. Four types of helices were formed in HU18-R and HU19-R by chiral transfer or induction. In HU18-R, small right-handed (R)-cma-Ni chain and large right-handed (R)-cma-Ni-1.3-dpp chain were constructed by chiral transfer. For HU19-R, helical nano-channel based on achiral 1.3-dpp ligands and Ni2+ ions was obtained from chiral induction method and small (R)-cma-Ni chain was built from chiral transfer. As semi-conducting materials, HU18-R and HU19-R indicate strong absorption capacity for UV–vis light and low-impedance properties. Under UV light, they have noticeable catalytic effects for degradation of methylene blue (MB). Moreover, magnetic tests confirmed that HU18-R and HU19-R have ferromagnetic and antiferromagnetic properties, respectively.

Insights into the Methyl Lactate and C4–C7 Alkanol Interactions from Densities, Viscosities, and CPA Modeling

Insights into the Methyl Lactate and C4–C7 Alkanol Interactions from Densities, Viscosities, and CPA Modeling

Antifungal Pseuboyenes A-J, Bergamotene-Derived Sesquiterpenoids from a Cold-Seep-Derived Pseudallescheria boydii.

A chemical investigation of a cold-seep-sediment-derived fungus, Pseudallescheria boydii CS-793, resulted in characterization of 10 novel bergamotene-derived sesquiterpenoids, pseuboyenes A-J (1-10). Their structures were elucidated by spectroscopic and X-ray crystallographic analyses as well as using the modified Mosher's method. Compound 1 represents the first example of a β-bergamotene containing a 6-oxobicyclo[3.2.1]octane nucleus adducted with a methyl lactate unit, while 8-10 involve a skeletal rearrangement from bergamotene. Compounds 2-5 showed significant antifungal activities against Colletotrichum gloeosporioides Penz. and Fusarium oxysporum with MICs ranging from 0.5 to 8 μg/mL. Compound 4 exhibited an in vitro anti-F. proliferatum effect with an EC50 value of 1.0 μg/mL.

One-pot catalytic conversion of sugars to methyl lactate over acid-base bifunctional Sn/MgO catalysts

Alkyl lactates represent such green added-value chemicals that commonly used as biodegradable green solvents, detergents, pharmaceutical intermediates et al. Catalytic conversion of carbohydrates to methyl lactate (MLA) is a representative way for high-value utilization of biomass and the key lies in the development of highly efficient catalysts. In methanol, strong acid or alkaline catalysts are usually used under high temperature and high pressure, suffering from problems such as low selectivity, high cost or contamination of environment. This study aims to develop an acid-base bifunctional heterogeneous catalyst for the one-pot conversion of sugars to MLA under mild conditions. Sn/Mg composite oxides was synthesized by a coprecipitation method and further modified by poly (vinyl imidazole) ([PVIM]) to tune the hydrophilicity. Effect of polymer and Sn amount, calcination temperature, reaction temperature, catalyst dosage, and substrate concentration were investigated. The acid-base properties were characterized by NH3-TPD, pyridine-FTIR and CO2-TPD analysis. It was found that the presence of medium acid sites and medium base sites played an important role to the cascade reactions of carbohydrates to MLA. An optimum MLA yield of 55.4% was achieved over 10[PVIM]-5Sn/MgO (0.05 g) with complete conversion of glucose (28 mM) at 140 ℃, 2 MPa N2 for 10 h. The reaction conditions are mild and no strong acid or strong base catalyst is required. Furthermore, a possible reaction mechanism was proposed that the introduction of [PVIM] effectively regulated the local microenvironment of active sites and the acid base synergism greatly promoted the retro-aldol condensation, dehydration and hydrogen transfer reactions during the conversion of glucose to MLA.

Synthesis of acrylic acid from methyl lactate over calcium phosphate catalysts in a fixed bed reactor: time-on-stream behavior and kinetic analysis

Transformation of methyl lactate to acrylic acid was investigated over Ca3(PO4)2, Ca2(P2O7) and their mixture in the temperature range of 250-425 °C. The initial concentration of methyl lactate in water was varied from 2 wt% to neat methyl lactate. The results showed that these phosphate catalysts did not contain any measurable amounts of either acid sites or basic sites. The best catalyst was Ca3(PO4)2 giving 62% selectivity to acrylic acid at 75% conversion at 400 °C using GHSV of 95280 h−1 and 2 wt% methyl lactate in the initial feed. This catalyst exhibited larger surface area in comparison to Ca2(P2O7). Elemental analysis revealed that some Ca leaching occurred during reaction, while in case of Ca2(P2O7) the calcium leaching was 3.4 fold higher than observed for Ca3(PO4)2. Long-term results over Ca3(PO4)2 showed that extensive catalyst deactivation occurred during the first 11 h time-on-stream, after which the activity dropped only slightly. In addition to kinetic studies with different parameters, also, kinetic modeling was performed and the activation energies for formation of different products were determined over different catalysts.

Glucose conversion process to methyl lactate catalyzed by SnCl4-based homogeneous catalysis

Biomass is a renewable alternative to fossil fuels and a valuable source of chemicals. In this study, a facile and efficient method was established to improve the selectivity of methyl lactate (MLA) for the homogeneous Lewis acid catalyzed chemical conversion of glucose and methanol. The effects of catalyst dosage, reaction temperature, and reaction time were systematically investigated, with an emphasis on the variation trends of MLA and other by-products. Through process optimization, the best catalyst molar ratio was 0.075 to 0.1, the reaction temperature was 170 to 180 °C, and the reaction time was 3 h. Under these conditions, the conversion of glucose in methanol exceeded 98%, and the yield of MLA was greater than 40%.

Ultrafast and selective chemical recycling of PLA to methyl lactate by using MHMDS as simple catalysts

The depolymerization of waste plastics into high-value products is a promising solution to address the plastic crisis. Among this field, catalytic activity and selectivity of depolymerization catalyst are of great concerns. Accordingly, in this work, a simple catalytic system was explored in detail to achieve the fast and selective chemical recycling of PLA into methyl lactate. Using commercially available M[bis(trimethylsilyl)amide] (MHMDS, M = Li, Na, K) as catalysts, the depolymerization of PLA was completed within a few minutes at room temperature. The selectivity and optical purity of the depolymerized product methyl lactate are greater than 99 %. The effect of conditions such as metal center, catalyst form, and solvent on depolymerization was investigated. Moreover, the gram-grade depolymerization, selective depolymerization of blended or mixed PLA plastic, and the recyclability of catalyst were further explored. This work accomplishes the path of highly selective and active depolymerization of PLA under mild conditions, thereby promoting sustainable development of PLA.

Production of Methyl Lactate with Sn-USY and Sn-β: Insights into Real Hemicellulose Valorization.

Potassium exchanged Sn-β and Sn-USY zeolites have been tested for the transformation of various aldoses (hexoses and pentoses), exhibiting outstanding catalytic activity and selectivity toward methyl lactate. Insights into the transformation pathways using reaction intermediates-dihydroxyacetone and glycolaldehyde-as substrates revealed a very high catalytic proficiency of both zeolites in aldol and retro-aldol reactions, showcasing their ability to convert small sugars into large sugars, and vice versa. This feature makes the studied Sn-zeolites outstanding catalysts for the transformation of a wide variety of sugars into a limited range of commercially valuable alkyl lactates and derivatives. [K]Sn-β proved to be superior to [K]Sn-USY in terms of shape selectivity, exerting tight control on the distribution of produced α-hydroxy methyl esters. This shape selectivity was evident in the transformation of several complex sugar mixtures emulating different hemicelluloses-sugar cane bagasse, Scots pine, and white birch-that, despite showing very different sugar compositions, were almost exclusively converted into methyl lactate and methyl vinyl glycolate in very similar proportions. Moreover, the conversion of a real hemicellulose hydrolysate obtained from Scots pine through a simple GVL-based organosolv process confirmed the high activity and selectivity of [K]Sn-β in the studied transformation, opening new pathways for the chemical valorization of this plentiful, but underutilized, sugar feedstock.

Fluorescent Zn(II) coordination polymer constructed by (R)-2-(1-carboxyethoxy)terephthalic acid as a probe for selective identification of Cr2O7 2− and MnO4 −

Ligand (R)-2-(1-carboxyethoxy)terephthalic acid ((R)-H3CTA) with excellent fluorescence has been prepared from (S)-methyl lactate and 2-hydroxyterephthalic acid. With the help of 4,4′-bipyridine (4,4′-BIP), (R)-H3CTA assembled with Zn2+ to obtain {[Zn((R)-CTA)(4,4′-BIP)2] · H2O} n (HU13-R ) under hydrothermal conditions. In HU13-R , (R)-CTA3− anions and Zn(II) centers resulted in a (R)-CTA-Zn layer, and then adjacent (R)-CTA-Zn layers and 4,4′-BIP ligands further formed a typical pillared-layer structure with a (3,5)-connected net. Besides excellent water stability, HU13-R has strong solid-state fluorescence. As a bright luminescent material, detection limit from HU13-R is up to 3.22 × 10−6 M for Cr2O7 2− and 5.92 × 10−6 M for MnO4 −, showing high sensitivity for anions. The presence of different anions does not interfere with its recognition ability for Cr2O7 2− and MnO4 −.

An encapsulation strategy to design an In-TS-1 zeolite enabling high activity and stability toward the efficient production of methyl lactate from fructose

Encapsulated In-TS-1 zeolite, demonstrating outstanding catalytic activity and stability, were effectively synthesized and utilized for the efficient one-pot conversion of fructose into methyl lactate (MLA).

Bifunctional Au-Sn-SiO2 catalysts promote the direct upgrading of glycerol to methyl lactate.

Valuable alkyl lactates can be obtained from (waste) glycerol, through a two-step process that entails (i) the oxidation of glycerol to dihydroxyacetone (DHA) catalyzed by support Au nanoparticles and (ii) a rearrangement of DHA with an alcohol effectively catalyzed by Sn-based heterogeneous catalysts. To solve selectivity and processing issues we propose to run the process as a cascade reaction, in one step, and with a single bifunctional catalyst. Tackling the challenge associated with the preparation of such bifunctional catalysts, here, an aerosol-assisted sol-gel route is exploited. The catalysts feature small Au nanoparticles (3-4 nm) embedded at the surface of mesoporous Sn-doped silica microspheres. The preparation successfully leads to insert both active sites in their most active forms, and in close proximity. With the bifunctional catalysts, the yield for the final product of the cascade reaction (methyl lactate) is higher than the DHA yield when only the first reaction is carried out. This highlights a beneficial substrate channeling effect which alleviates side reactions. Interestingly, the bifunctional catalysts also markedly outcompeted mechanical mixtures of the corresponding monofunctional Au- and Sn-based catalysts. Thus, the spatial proximity between the two active sites in bifunctional catalysts is identified as a key to stir the cascade reaction towards high lactate yield.

Probing microhydration-induced effects on carbonyl compounds.

Characterizing the microhydration of organic molecules is a crucial step in understanding many phenomena relevant to atmospheric, biological, and industrial applications. However, its precise experimental and theoretical description remains a challenge. For four organic solutes containing a CO bond, and included in the recent HyDRA challenge [T. L. Fischer, M. Bödecker, A. Zehnacker-Rentien, R. A. Mata and M. A. Suhm, Phys. Chem. Chem. Phys., 2022, 24, 11442-11454.], we performed a detailed study of different monohydrate isomers and their properties; these were cyclooctanone (CON), 1,3-dimethyl-2-imidazolidinon (DMI), methyl lactate (MLA), and 2,2,2-trifluoroacetophenone (TPH) molecules. As reported in the literature, the O-H elongation shift of the water molecule appears to be a good candidate for characterizing complexation-induced effects. We also show that CO elongation shift and UV-vis spectroscopy can be successfully used for these purposes. Besides, we present a comparative analysis of the strengths of non-covalent interactions within these monohydrated complexes based on interpretative tools of quantum chemistry, including topological analysis of electron density (ρ), topological analysis of electron pairing function, and analysis of the core-valence bifurcation index (CVBI), which exhibits a close linear dependency on ρ. Accordingly, a classification of intermolecular water-solute interactions is proposed.