Glycidyl Ether Research Articles

Analysis of the mechanical behavior of polyurethane thermoset elastomers based on hydrogen bonding between different crosslinking point structures

To reveal the effect of polyurethane crosslinking point structures on the mechanical properties of polyurethane thermoset elastomers, using amorphous prepolymer poly (azide glycidyl ether) (GAP) as a binder, polyisocyanate cross-linker N100 and hexamethylene diisocyanate (HDI) as curing agents, trimethylolpropane (TMP) as a crosslinking agent, two GAP polyurethane thermoset elastomers that have similar chemical crosslinking network density, elastomer S0 prepared from GAP and N100 and elastomer S4 prepared from GAP and HDI/TMP, were selected to study in detail. DSC and XRD analysis indicated that two GAP polyurethane thermoset elastomers both exhibit stable amorphous aggregation structure below 80 °C. Mechanical properties test showed that thermoset elastomer S0 gives higher tensile modulus, lower tensile strength and elongation rate, while thermoset elastomer S4 gives lower tensile modulus, higher tensile strength and elongation rate. In-situ FTIR and low field nuclear magnetic resonance (LF-NMR) analysis suggested that there exists stronger urea carbonyl hydrogen bonding structure within thermoset elastomer S0, while weaker urethane carbonyl hydrogen bonding structure within thermoset elastomer S4. The different strength of the hydrogen bonding between crosslinking points imparts different segment mobility to S0 and S4. Dynamic thermodynamic analysis (DMA) indicated that, stronger urea carbonyl hydrogen bonding has suppressed segments mobility and thermoset elastomer S0 present lower loss modulus and loss factor, while thermoset elastomer S4 present higher loss modulus and loss factor because there just exist weaker urethane carbonyl hydrogen bonding interaction between crosslinking points.

Influence of polymers with surfactant properties as pour point depressants on the cold flow properties of diesel fuel

Polymers and surfactants are increasingly applied to improve the cold flow properties of diesel fuel. However, their depressive effects are closely related to the molecular structure of the structuring units. In this study, the structural properties of surfactants were applied to synthesise a series of polymers consisting of tetradecyl methacrylate and ether compounds as structural units, with the long alkyl chain and ether compounds acting as hydrophobic and hydrophilic groups, respectively. The polymers consisting of tetradecyl methacrylate and ether compounds combined the advantages of polymers and surfactants in improving the cold flow properties of diesel. Besides, the effects of different functional groups, molar ratios and additive amounts on the improvement of diesel fuel low–temperature fluidity were investigated. The results indicated that 1500 ppm polymer with tetradecyl methacrylate and allyl glycidyl ether as structural monomers at a molar ratio of 6:1 as polymer pour point depressant (PPD) showed a greater enhancement of cold filter plugging point and solid point of diesel (ΔCFPP = 12 ℃, ΔSP = 17 ℃). The molecular structures of efficient pour point depressants were screened and the polymer composition was broadened. Finally, differential scanning calorimeter, rheological and polarising optical microscopy were used to analyse the changes in wax crystals size and morphology in pure diesel and diesel treated with polymer PPDs, and a mechanism for polymer PPDs with surfactant structural properties to change the crystallisation and aggregation behaviour of wax crystals was inferred.

Unraveling the ablative behavior through the design of a POSS-Benzoxazine/EPDM network under harsh environments

In order to meet the demands of the insulation layer in the swiftly advancing aerospace thermal protection system and enhance the ablation resistance of ethylene propylene diene rubber (EPDM) insulation layer, a novel EPDM ablation resistance composite was designed by integrating benzoxazine fine-tuned with octal (propyl glycidyl ether) polyhedral oligomeric silsesquioxane (BA-POSS) into the network structure of EPDM. The resulting composite exhibited a more densely cross-linked EPDM/BA-POSS network, consequently augmenting both the mechanical and ablation properties of the EPDM ablation resistance composite. The cross-linking density and tensile strength of EPDM/BA-POSS composite with 18 phr (parts per hundred rubber) BA-POSS increased by 78.4% and 30.7%, respectively, and the linear ablation rate significantly reduced by 47.7%, compared with EPDM composite without BA-POSS. Additionally, the ablation mechanism of EPDM/BA-POSS composites was elucidated through an investigation of the thermo-chemical transformation and analysis of the ablated carbon layer. This study contributes novel insights and methodologies for the future design of low-density rocket motor insulation compounds that offer cost efficiency, enhanced functionality, and wider applicability.

The synthesis of multifunctional cellulose graft alternating copolymers of 3,4-dihydrocoumarin and epoxides in DBU/DMSO/CO2 solvent system

Cellulose graft copolymers having well-defined structures could incorporate the characteristics of both the cellulose skeleton and side chains, providing a new method for the preparation functionalised cellulose derivatives. Herein, a series of multifunctional cellulose grafted, alternating 3,4-dihydrocoumarin (DHC) and epoxide (EPO) copolymers (cell-g-P(DHC-alt-EPO)) were prepared in a metal-free DBU/DMSO/CO2 solvent system without adding additional catalyst. Four examples of cell-g-P(DHC-alt-EPO) with tunable thermal and optical properties were synthesized by copolymerization of DHC with styrene oxide (SO), propylene oxide (PO), cyclohexene oxide (CHO) or furfuryl glycidyl ether (FGE) onto cellulose. The nonconjugated cell-g-P(DHC-alt-EPO) showed UV absorption properties with the maximum absorption peak at 282 nm and 295 nm and photoluminescence performance. A clustering-triggered emission mechanism was confirmed and consistent with DFT theoretical calculations. In DMSO solution, the copolymer (DHCSO5) with DP of 11.64 showed ACQ behaviour as the concentration increased. In addition, DHCSO5 had good antioxidant capacity with an instantaneous radical scavenging activity of 2,2-diphenyl-1-picrylhydrazine (DPPH) up to 65 % at a concentration of 40 mg/ ml and increased to 100 % after 30 min. Thus, the multifunctional cell-g-P(DHC-alt-EPO) materials had a variety of potential applications in the fields of fluorescent printing, bio-imaging, UV- shielding and antioxidants.

High-Performance Reversible Furan-Maleimide Resins Based on Furfuryl Glycidyl Ether and Bismaleimides.

Two reversible furan-maleimide resins, in which there are rigid -Ph-CH2-Ph- structures and flexible -(CH2)6- structures in bismaleimides, were synthesized from furfuryl glycidyl ethers (FGE), 4,4'-diaminodiphenyl ether (ODA), N,N'-4,4'-diphenylmethane-bismaleimide (DBMI), and N,N'-hexamethylene-bismaleimide (HBMI). The structures of the resins were confirmed using Fourier transform infrared analysis, and the thermoreversibility was evidenced using differential scanning calorimetry (DSC) analysis, as well as the sol-gel transformation process. Mechanical properties and recyclability of the resins were preliminarily evaluated using the flexural test. The results show the Diels-Alder (DA) reaction occurs at about 90 °C and the reversible DA reaction occurs at 130-140 °C for the furan-maleimide resin. Thermally reversible furan-maleimide resins have high mechanical properties. The flexural strength of cured FGE-ODA-HBMI resin arrives at 141 MPa. The resins have a repair efficiency of over 75%. After being hot-pressed three times, two resins display flexural strength higher than 80 MPa.

Sustainable synthesis of cyclic carbonates from CO2 using zinc adeninium bromide as a biorenewable catalyst

The design of green catalysts for CO2 utilization purposes is considered a great challenge and a motivation for a sustainable future. In this work, a first-time zinc adeninium bromide (Zn-AHBr) was synthesized and fully characterized using far and mid ATR-FTIR, 1D and 2D NMR spectroscopy, including 1H, 13C and [1H,15N] correlation spectroscopy (HMBC/HSQC), cyclic voltammetry and further supported with theoretical calculations involving energetics using Density functional theory (DFT). The Zn-AHBr was exploited as an unprecedented biorenewable, sustainable catalyst for CO2/epoxide coupling at ambient reaction conditions (1 atm, 80 °C over 8 to 16 h) with quantitative conversion of epichlorohydrin, epibromohydrin, glycidol, glycidyl ether, and 1,2-epoxy-3-phenoxypropane. Moreover, other Zn-AHX (X: Cl and I) showed excellent up to quantitative conversions toward epichlorohydrin cycloaddition. Furthermore, a plausible mechanism for the cycloaddition reaction was investigated using DFT calculations which indicated a relatively low activation energy (1.1 kcal.mol−1) for the epoxide ring opening, and a much higher value (9.4 kcal.mol−1) for the cyclic carbonate ring closure as a rate determining step for the reaction.

A novel CO2 based UV-induced peelable adhesive for wafer dicing

Poly (propylene carbonate) diol with double-bonds on the side chains (PPCAGE) was synthesized form CO2, propylene oxide (PO), polyether diol (PPG) and allyl glycidyl ether (AGE). Then, three kinds of CO2 based polyurethane oligomers (PPCAGE-PU) (PPCAGE-PUA, PPCAGE-PUB and PPCAGE-IPDI, respectively) with different contents of double bond were prepared through the reaction of PPCAGE, isophorone diisocyanate (IPDI) and hydroxyethyl acrylate (HEA). The content of -NCO was adjusted by varying the ratio of -NCO terminated prepolymer and HEA. Acrylate copolymer with side double bonds and hydroxyl groups (GMA-PSA) was synthesized by the ring-opening reaction of glycidyl methacrylate (GMA) and acrylate copolymer (PSA) containing -COOH and -OH. CO2 based UV-induced peelable adhesive was prepared by mixing PPCAGE-PU, GMA-PSA, active diluent and photoinitiator. The structure of PPCAGE was confirmed by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H NMR). The reaction of PPCAGE-PUB and GMA-PSA was monitored by FT-IR, companied by the titration of -NCO and epoxide. The molecular weight of PSA and GMA-PSA was determined by gel permeation chromatography (GPC). The surface morphology of the adhesive was observed by scanning electron microscopy (SEM). The viscoelasticity of adhesive was measured by real-time rheology. The 180° peel strength, micro-surface morphology, gel content, unsaturation conversion and glass transition temperature of UV-induced peelable adhesive were characterized. The results showed that the peel strength of adhesive was 17.82 N/25 mm before UV curing. After UV curing, the surface morphology changed from smooth to rough, the peel strength decreased to 0.08 N/25 mm and the modulus of the PSA increased due to the cross-linking. DSC results showed that the glass transition temperature increased after UV curing.

Comparative study of reactive diluents with different molecular structures on the curing properties of epoxy adhesives and the interface bonding properties with mortar

Epoxy adhesives for concrete cracks repair may necessitate the addition of reactive diluent to decrease their viscosity. However, research on the effect of different reactive diluents on the various properties of epoxy adhesives remains insufficient. In this paper, three reactive diluents, including monofunctional alkyl C12–C14 glycidyl ether (AGE), butyl glycidyl ether (BGE) and difunctional 1,4-butanediol diglycidyl ether (BDDE) are utilized to comparatively study the different effects on the viscosity, exothermic temperature, mechanical properties, and bond strength with cement mortar of the adhesives. The results show that the addition of BDDE increases the maximum curing temperature of the adhesives, whereas AGE and BGE both causes a decrease. The epoxy adhesive with AGE or BGE shows greater ultimate tensile strain, but a more obvious reduction in Young's modulus than that with BDDE at the same concentration. BDDE improves the bond strength of the adhesive-mortar interface whereas AGE and BGE both decrease it. Moreover, the bond strength shows a positive correlation with the hydroxyl content on the surface of cured epoxy. Comparing with AGE and BGE, BDDE increases the hydroxyl content, resulting in the strongest bond strength.

Construction and evaluation of environment-friendly POSS multi-crosslinked mulch film based on bone gelatin

The non-degradable traditional polyethylene (PE) mulch film has caused great harm to both the ecological environment as well as human health. Therefore, the biodegradable bone gelatin (B-Gel) was innovatively selected to build the mulch film. To further enhance the toughness of the B-Gel mulch films, a POSS star-shaped polymer/bone gelatin (P(POSS-AGE-HEA)/B-Gel) composite was prepared by introducing POSS star-shaped polymer into B-Gel via in situ polymerization using polyhedral oligomeric silsesquioxane (POSS), allyl glycidyl ether (AGE) and hydroxyethyl acrylate (HEA) as raw material, and then was cast to obtain the P(POSS-AGE-HEA)/B-Gel mulch film. The epoxy group of POSS star-shaped polymer with the -COOH and -NH2 of B-Gel forms a covalent bond, and the hydroxyl group with the active groups of B-Gel forms hydrogen bonds. Meanwhile, the multiple side chains of POSS star-shaped polymer are intertwined with B-Gel. These covalent and hydrogen bonds as sacrificial bonds for effective energy dissipation giving the bone gelatin-based film excellent mechanical properties with a tensile strength of 7.56 ± 0.64 MPa and elongation at break of 197.49 ± 17.63 %. Additionally, it also demonstrated sound water vapor barrier, surface hydrophobicity, light transmittance and the effect of facilitating the growth and germination ratio (93.75 %) of wheat.

The effect of modification of gelcoat based on unsaturated polyester resin with polysiloxanes on icephobicity, hydrophobicity and durability

Ice accumulation on aerodynamic surfaces is a well-known aspect in various industries, including wind turbines. Many solutions have been developed for several years to deal with this problem, but until now no suitable and energy-sufficient method available for industrial applications has been found. A potential solution is using hydrophobic and/or icephobic coatings, which would allow one to reduce ice adhesion to surfaces. In this study, modifications of a gelcoat based on unsaturated polyester resin with in-house synthesized polysiloxanes dual-functionalized with allyl glycidyl ether (AGE) and hexyl (HEX) or octyl (OCT) groups were used. Most of the chemical modifications used resulted in an increase in surface hydrophobicity (an increase in water contact angle and a decrease in contact angle hysteresis) and an improvement in icephobicity - a reduction in ice adhesion. The lowest ice adhesion achieved a value equal to 221 kPa (the decrease in ice adhesion was 36 % compared to the unmodified surface). The highest water contact angle exhibited a value of 96 °C. Furthermore, correlations were observed between roughness/wettability and ice adhesion: as roughness and wettability decrease, ice adhesion is reduced. The study also determined the durability of the produced surfaces after 100 icing/deicing cycles and the zeta potential surface.

One-step synthesis of ferrocenyl glycidyl ethers as combustion catalysts for the thermal decomposition of ammonium perchlorate

As an oxidant, the pyrolysis behavior of ammonium perchlorate is the key to the combustion of composite solid propellants. Seeking a suitable catalyst to promote AP decomposition has drawn much attention. Ferrocene-based compounds are often used as burning rate catalysts because of their excellent catalytic effect. However, ferrocene-based burning rate catalysts are prone to migration during storage of propellants. In this study, six ferrocenyl glycidyl ethers were designed and synthesized to improve the anti-migration properties, and the related spectra characterization techniques were adopted to confirm their molecular structures. Furthermore, their related properties and mechanisms were also studied. As a result, they showed good redox performance, positive promotion on AP decomposition, excellent combustion and mechanical performance. Meanwhile, they had a higher anti-migration behavior compared with catocene and ferrocene. This study demonstrates that ferrocenyl glycidyl ethers have great potential to be applied as multifunctional burning rate catalysts in composite solid propellants.

Thermal Stable and Flexible Bio‐Based Polybenzoxazine with Epoxy‐Functionalized Poly(dimethylsiloxane) Hybrids

AbstractIn this study, a monofunctionalized bio‐based benzoxazine monomer (VAnBZ‐CN) is synthesized by condensation of vanillin, formaldehyde, and aniline, and a bifunctional epoxy‐functionalized poly(dimethylsiloxane) (PDMS‐epoxy) is also prepared through hydrosilylation reactions with allyl glycidyl ether. By blending the inorganic PDMS‐epoxy with the VAnBZ‐CN benzoxazine monomer, an organic/inorganic hybrid material is formed, which exhibited enhanced thermal stability after thermal curing polymerization. The improved thermal stability observed in the hybrid material can be attributed to a combination of the formation of the triazine structure by VAnBZ‐CN and the presence of the inorganic part of PDMS‐epoxy on the surface. For example, the PDMS‐epoxy/VAnBZ‐CN = 1/1 hybrid showed the thermal decomposition temperature (Td10) of 309 °C, the glass transition temperature (Tg) of 165 °C, and the char yield of 54 wt.% after the thermal curing polymerization process conducted at 240 °C based on thermogravimetric (TGA) and dynamic mechanical analyses (DMA). Furthermore, the char yield of the hybrid material with PDMS‐epoxy/VAnBZ‐CN = 1/3 is higher than that both of pure VAnBZ‐CN and PDMS‐epoxy after the thermal curing polymerization process. This result indicates that the addition of PDMS‐epoxy resin can improve the formation of a char residue and then enhance the resistance to thermal decomposition for their overall thermal stabilities.

Synthesis of Polyethylene Glycol-Poly(glycerol carbonate) Block Copolymeric Micelles as Surfactant-Free Drug Delivery Systems.

We report the synthesis of block copolymers of monomethoxylated polyethylene glycol and poly(glycerol carbonate) (mPEG-b-PGC) via the ring-opening polymerization of benzyl glycidyl ether, monomethoxylated polyethylene glycol, and carbon dioxide using a cobalt salen catalyst. The resulting block copolymers display high polymer/cyclic carbonate selectivity (>99%) and, if two oxirane monomers are used, random incorporation into the polymer feed. The resulting diblock mPEG-b-PGC polymer shows promise as a nanocarrier for surfactant-free, sustained chemotherapeutic delivery. mPEG-b-PGC, with paclitaxel conjugated to the pendant primary alcohol of the glycerol polymer backbone, readily forms 175 nm diameter particles in solution and contains 4.6 wt % paclitaxel (PTX), which is released over 42 days. The mPEG-b-PGC polymer itself is noncytotoxic, whereas the PTX-loaded nanoparticles are cytotoxic to lung, breast, and ovarian cancer cell lines.

Synthesis and characterization of chitosan-polyacrylamide cryogels for the purification of human IgG by IMAC

The performance of polyacrylamide-chitosan monolithic cryogels functionalized with iminodiacetic acid (IDA) was evaluated for the chromatographic separation of Immunoglobulin G (hIgG) from human serum using immobilized metal ion affinity chromatography (IMAC). Monoliths were prepared using the cryopolimerization technique, varying the type of chitosan (CS) used, and final concentrations of allyl glycidyl ether (AGE) and glutaraldehyde (GA), keeping the amount of acrylamide (AAm) and bisacrylamide (MBAm) constant. Cryogels were characterized by their surface area, SEM, FTIR, porosity, ligand density, mechanical resistance, and flow rate. Purification of hIgG was investigated using the PAAm-CS-GA-AGE-IDA cryogel chelated with Cu(II) and Ni(II) ions. The analysis demonstrated isolation of hIgG from human serum in a sodium phosphate buffer at pH 7.0 containing 2 mmol/L imidazole on PAAm-CS-GA-AGE-IDA-Ni(II) cryogel, with purity of 96% and purification factor of 12.4 (based on total protein concentration and radial immunodiffusion). The hIgG adsorption equilibrium data on the IDA-Ni(II) cryogel followed the Langmuir–Freundlich isotherm model, showing maximum hIgG binding capacity of 31.19 mg hIgG/g dry cryogel and a dissociation constant in the order of 10−7 to 10−8 mol/L. These results demonstrate the potential of PAAm/CS-based cryogels with chelated Ni(II) ions for the purification of hIgG from human serum using IMAC.

Cardanol derivatives as compatibilizers for strengthening and toughening polylactic acid/bamboo fiber bio‐composites

AbstractThe application of bamboo fibers (BFs) as a reinforcing filler in polylactic acid (PLA) is hindered by their poor compatibility owing to the intrinsic hydrophilia of BFs and the hydrophobicity of PLA. To solve this issue, cardanol (CD) and epoxidized cardanol glycidyl ether (ECGE) were used as compatibilizers to strengthen and toughen PLA/BF bio‐composites, to the best of our knowledge, preparing PLA/BF/CD and PLA/BF/ECGE bio‐composites. The impact strengths of the synthesized bio‐composites increased from 7.75 to 23.75 and 7.75 to 23.95 kJ/m2, respectively, compared with that of a PLA/BF composite without compatibilizer. The investigation of the mechanical properties, crystallization, fractured surface morphology, and solvent stress‐cracking resistance properties revealed that the toughening mechanism of the PLA/BF/CD bio‐composites are mainly based on the plasticization of CD, which results in high impact toughness but low tensile strength. Moreover, the modification with ECGE improves the impact and tensile strengths of the bio‐composite owing to the following factors: (1) the epoxy groups of ECGE generate strong interactions with the BF surface and PLA to form an enhanced interfacial structure; (2) when present at high concentrations, chain extension reaction between ECGE and PLA to increase the molecular chain entanglement of PLA; and (3) upon curing and crosslinking, ECGE forms an entangled network structure that toughens the matrix.

Ring Opening Copolymerization of Boron-Containing Anhydride with Epoxides as a Controlled Platform to Functional Polyesters.

Boron-functionalized polymers are used in opto-electronics, biology, and medicine. Methods to produce boron-functionalized and degradable polyesters remain exceedingly rare but relevant where (bio)dissipation is required, for example, in self-assembled nanostructures, dynamic polymer networks, and bio-imaging. Here, a boronic ester-phthalic anhydride and various epoxides (cyclohexene oxide, vinyl-cyclohexene oxide, propene oxide, allyl glycidyl ether) undergo controlled ring-opening copolymerization (ROCOP), catalyzed by organometallic complexes [Zn(II)Mg(II) or Al(III)K(I)] or a phosphazene organobase. The polymerizations are well controlled allowing for the modulation of the polyester structures (e.g., by epoxide selection, AB, or ABA blocks), molar masses (9.4 < Mn < 40 kg/mol), and uptake of boron functionalities (esters, acids, "ates", boroxines, and fluorescent groups) in the polymer. The boronic ester-functionalized polymers are amorphous, with high glass transition temperatures (81 < Tg < 224 °C) and good thermal stability (285 < Td < 322 °C). The boronic ester-polyesters are deprotected to yield boronic acid- and borate-polyesters; the ionic polymers are water soluble and degradable under alkaline conditions. Using a hydrophilic macro-initiator in alternating epoxide/anhydride ROCOP, and lactone ring opening polymerization, produces amphiphilic AB and ABC copolyesters. Alternatively, the boron-functionalities are subjected to Pd(II)-catalyzed cross-couplings to install fluorescent groups (BODIPY). The utility of this new monomer as a platform to construct specialized polyesters materials is exemplified here in the synthesis of fluorescent spherical nanoparticles that self-assemble in water (Dh = 40 nm). The selective copolymerization, variable structural composition, and adjustable boron loading represent a versatile technology for future explorations of degradable, well-defined, and functional polymers.

Multi-Armed Star-Shaped Block Copolymers of Poly(ethylene glycol)-Poly(furfuryl glycidol) as Long Circulating Nanocarriers.

Multi-arm star-shaped block copolymers with precisely tuned nano-architectures are promising candidates for drug delivery. Herein, we developed 4- and 6-arm star-shaped block copolymers consisting of poly(furfuryl glycidol) (PFG) as the core-forming segments and biocompatible poly(ethylene glycol) (PEG) as the shell-forming blocks. The polymerization degree of each block was controlled by adjusting the feeding ratio of a furfuryl glycidyl ether and ethylene oxide. The size of the series of block copolymers was found to be less than 10 nm in DMF. In water, the polymers showed sizes larger than 20 nm, which can be related to the association of the polymers. The star-shaped block copolymers effectively loaded maleimide-bearing model drugs in their core-forming segment with the Diels-Alder reaction. These drugs were rapidly released upon heating via a retro Diels-Alder step. When the star-shaped block copolymers were injected intravenously in mice, they showed prolonged blood circulation, with more than 80% of the injected dose remaining in the bloodstream at 6 h after intravenous injection. These results indicate the potential of the star-shaped PFG-PEG block copolymers as long-circulating nanocarriers.

Enantiocomplementary synthesis of β-adrenergic blocker precursors via biocatalytic nitration of phenyl glycidyl ethers

Enantiopure β-nitroalcohols, as an important class of nitro-containing compounds, are essential building blocks in pharmaceutical and organic chemistry, particularly for the synthesis of β-adrenergic blockers. In this study, we present the successful protein engineering of halohydrin dehalogenase HHDHamb for the enantioselective bio-nitration of various phenyl glycidyl ethers to the corresponding chiral β-nitroalcohols, using the inexpensive, commercially available, and safer nitrite as a nitrating agent. The chiral (R)- and (S)-1-nitro-3-phenoxypropan-2-ols were synthesized by the several enantiocomplementary HHDHamb variants through the whole-cell biotransformation, which showed good catalytic efficiency (up to 43% isolated yields) and high optical purity (up to >99% ee). In addition, we also demonstrated that the bio-nitration method was able to tolerate the substrate at a high concentration of 1000 mM (150 g/L). Furthermore, representative synthesis of two optically active enantiomers of the β-adrenergic blocker metoprolol was successfully achieved by utilizing the corresponding chiral β-nitroalcohols as precursors.

Asymmetric Synthesis of Methoxylated Ether Lipids: Total Synthesis of a Triene C18 : 3 Omega‐8 MEL Derivative

AbstractThe asymmetric synthesis of a triene C18 : 3 n‐8 methoxylated ether lipid (MEL) of the 1‐O‐alkyl‐sn‐glycerol type is described by two different routes. The C18 : 3 hydrocarbon chain is attached by an ether linkage to the pro‐S hydroxymethyl group of the glycerol backbone, and constitutes an all‐cis methylene skipped triene framework, along with a methoxyl group in the 2’‐position and R‐configuration at the resulting chiral centre. The initial synthesis was based on the polyacetylene approach involving a semi‐hydrogenation of the resulting triyne. A modified approach based on a combined polyacetylene‐Wittig strategy was also successfully executed and an attempt made to compare and evaluate these strategies. Both syntheses were started from our previously described enantio‐ and diastereomerically pure isopropylidene‐protected glyceryl glycidyl ether, a double‐C3 building block designed as a head group synthon for synthesis of various types of MELs which was shown to suit the Wittig‐based approach very well.

Pilot-Scale Production of Hemicellulose Ethers from Softwood Hemicelluloses Obtained from Compression Screw Pressate of a Thermo-Mechanical Pulping Plant.

Bio-derived materials are becoming increasingly sought-after as a sustainable alternative to petrochemical-derived polymers. In the present pilot-scale study, a hemicellulose-rich compression screw pressate, obtained from the pre-heating stage of thermo-mechanical pulping (TMP) of radiata pine, was purified by treatment with adsorbent resin (XAD7), then ultrafiltered and diafiltered at 10 kDa to isolate the high-molecular weight (MW) hemicellulose fraction (yield 18.4% on pressate solids), and, finally, reacted with butyl glycidyl ether to plasticise the hemicelluloses. The resulting light brown hemicellulose ethers (yield 102% on the isolated hemicelluloses) contained ca. 0.5 butoxy-hydroxypropyl side chains per pyranose unit and had weight- and number-average MWs of 13,000 Da and 7200 Da, respectively. The hemicellulose ethers may serve as raw material for bio-based products such as barrier films.