The formation and extractive desulfurization (EDS) mechanisms of aromatic acid based deep eutectic solvents (DESs) were studied experimentally and through quantum chemistry calculations. Hydrogen ...bonding and van der Waals forces were investigated as the driving forces for the formation of aromatic acid based DESs by means of 1H NMR and FTIR spectroscopy, and DFT calculations. The driving forces of EDS were also studied. The results showed that van der Waals forces and other weak interactions were the main diving forces for EDS, and the structures of the aromatic acid based DESs did not change after EDS. The interaction energy between the aromatic acid based DESs and thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT) were calculated by DFT to understand the EDS order: TH<BT<DBT. Moreover, the optimal EDS conditions were studied. The amount of BT (500 ppm) was reduced to below 10 ppm under the optimal conditions of using triethylamine/o‐hydroxybenzoic acid (TEA/OHBA). The desulfurization efficiency of TEA/OHBA was stable after ten cycles, and the mechanical loss of TEA/OHBA could be ignored.
The forces that bind: The formation and extractive desulfurization mechanisms of aromatic acid based deep eutectic solvents (DESs; see figure) have been studied through experimental and theoretical methods. Hydrogen bonding and van der Waals forces have been investigated as the driving forces for the formation of these DESs
The functions of the materials composed of small molecules are highly dependent on their ordered molecular arrangements in both natural and artificial systems. Without ordered structure, small ...molecules hardly gain complicated functions, due to the absence of intermolecular covalent bond connection or strong network. Here, a low molecular weight spiropyran that could exhibit attractive photochromism and powerful adhesion property in disordered solid state is demonstrated. With maximum up to ∼8 MPa, the adhesion strength could be photoregulated in multiple levels, which also shows one‐to‐one correspondence to the specific color state. The working mechanism analysis on the photoregulated adhesion reveals that the isomer ratio of merocyanine form and the molecular packing density of spiropyran are the determining factors for the adhesion ability. The discovery of photoregulated adhesion from pure spiropyran provides a new strategy for developing functional materials by employing low molecular weight compounds.
Photoresponsive adhesives are attractive functional materials. Differentiating from the reported azobenzene‐containing adhesives with photoswitched adhesion‐on or off property, a low molecular weight spiropyran that could exhibit photoregulated adhesion ability in multiple levels is disclosed in this work. In disordered solid state, the reported spiropyran could also gain photochromism with five different color states, which show one‐to‐one correspondence to the adhesion ability. This work provides a new strategy for developing functional materials by employing low molecular weight compounds.
Epoxidation of α-Pinene Catalyzed by Amphiphilic Catalyst TS-1@Si/C Xing, Chen; Xie, Congxia
Qingdao Keji Daxue Xuebao. Ziran Kexue Ban = Journal of Qingdao University of Science and Technology. Natural Science Edition,
01/2022, Letnik:
43, Številka:
6
Journal Article
Amphiphilic mesoporous core-shell material TS-1@Si/C was prepared by hydrothermal method, and the morphology and structure of TS-1@Si/C were characterized by SEM, TEM, XRD and ammonia temperature ...programmed desorption. By using TS-1@Si/C as catalyst, 2,3-epoxypinane was synthesized from α-pinene with hydrogen peroxide as oxidant. When the n（Si）/n（Ti） molar ratio is 30 and the n（Si）/n（C） molar ratio is 14, the catalyst has the highest activity. The reaction conditions are as follows: α-pinene 3 mmol, catalyst（7.1% of the mass ratio of α-pinene）, hydrogen peroxide 50 mmol, acetonitrile 10 mL, water 4 mL, potassium carbonate 2 mmol, 50 ℃, and 4 h. The conversion of α-pinene was 81.41%, and the selectivity of 2,3-epoxypinane was 82.80%. The catalyst could be reused for 4 times, and the catalytic activity decreased. Amphiphilic catalyst can form stable water-oil-solid interface, increase the concentration of reaction substrate in the aqueous phase, and significantly improve the catalytic performance of epoxidation
Lycopene is increasing in demand due to its widespread use in the pharmaceutical and food industries. Metabolic engineering and synthetic biology technologies have been widely used to overexpress the ...heterologous mevalonate pathway and lycopene pathway in Escherichia coli to produce lycopene. However, due to the tedious metabolic pathways and complicated metabolic background, optimizing the lycopene synthetic pathway using reasonable design approaches becomes difficult. In this study, the heterologous lycopene metabolic pathway was introduced into E. coli and divided into three modules, with mevalonate and DMAPP serving as connecting nodes. The module containing the genes (MVK, PMK, MVD, IDI) of downstream MVA pathway was adjusted by altering the expression strength of the four genes using the ribosome binding sites (RBSs) library with specified strength to improve the inter-module balance. Three RBS libraries containing variably regulated MVK, PMK, MVD, and IDI were constructed based on different plasmid backbones with the variable promoter and replication origin. The RBS library was then transformed into engineered E. coli BL21(DE3) containing pCLES and pTrc-lyc to obtain a lycopene producer library and employed high-throughput screening based on lycopene color to obtain the required metabolic pathway. The shake flask culture of the selected high-yield strain resulted in a lycopene yield of 219.7 mg/g DCW, which was 4.6 times that of the reference strain. A strain capable of producing 219.7 mg/g DCW with high lycopene metabolic flux was obtained by fine-tuning the expression of the four MVA pathway enzymes and visual selection. These results show that the strategy of optimizing the downstream MVA pathway through RBS library design can be effective, which can improve the metabolic flux and provide a reference for the synthesis of other terpenoids.
(R)-(+)-perillyl alcohol is a naturally oxygenated monoterpene widely used as the natural flavor additives, insecticides, jet fuels and anti-cancer therapies. It was also readily available ...monoterpene precursors. However, this natural product is present at low concentrations from plant sources which are not economically viable. Therefore, alternative microbial production methods are rapidly emerging as an attractive alternative to make (R)-(+)-perillyl alcohol production more sustainable and environmentally friendly.
We engineered Escherichia coli to possess a heterologous mevalonate (MVA) pathway, including limonene synthase, P-cymene monoxygenase hydroxylase and P-cymene monoxygenase reductase for the production of (R)-(+)-perillyl alcohol. The concentration of (R)-(+)-limonene (the monoterpene precursor to (R)-(+)-perillyl alcohol) reached 45 mg/L from glucose. Enhanced (R)-(+)-perillyl alcohol production was therefore achieved. The strain produced (R)-(+)-perillyl alcohol at a titer of 87 mg/L and a yield of 1.5 mg/g glucose in a 5 L bioreactor fed batch system.
These datas highlight the efficient production of (R)-(+)-perillyl alcohol through the mevalonate pathway from glucose. This method serves as a platform for the future production of other monoterpenes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
(R)‐(+)‐perillyl alcohol is widely used in agricultural and anticarcinogenic fields. Microbial production of (R)‐(+)‐perillyl alcohol was investigated in this study. We optimized biosynthesis of ...(R)‐(+)‐perillyl alcohol in Escherichia coli by using neryl pyrophosphate synthase and NADPH regeneration. Engineering neryl pyrophosphate (NPP)‐supplied pathway resulted in a 4‐fold improvement of (R)‐(+)‐perillyl alcohol titer. Subsequently, combined engineering of p‐cymene monooxygenase (CymA) expression and module for NADPH regeneration exhibited a 15.4‐fold increase of titer over the initial strain S02. Finally, 453 mg/L (R)‐(+)‐perillyl alcohol was achieved in fed‐batch fermentation, which is the highest (R)‐(+)‐perillyl alcohol titer in E. coli.
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•Clean benzylation achieved by a lignin-based biomass solid acid.•The biomass sulfonated carbon presented superior acid strength and density.•The lignin-based solid acid catalysts ...have similar activities to molecular sieves.
Low-temperature carbonization–sulfonation two-step process or one-step sulfonation process was employed to draft sodium lignosulfonate (SLS), the primary biological macromolecule ingredient of papermaking black liquor, into lignin-based sulfonated carbon. The two-step lignin-based sulfonated carbon named SLC400,1S was found to be an efficient catalyst for clean Benzyl-alcohol (BA) route Friedel-Crafts (F-C) benzylation of benzene ring compounds. FT-IR, XRD, Raman spectra, XPS, SEM with EDX-mapping, TGA-DSC, acid-base titration, and n-butylamine–acetonitrile titration characterizations demonstrated that the specific two-step process could introduce porous properties and a large number of surface sulfonic, hydroxyl, and carboxyl active groups into the structure of the prepared material, which was found to account for the good catalytic performance for benzylation. Similar to that of hierarchical mesoporous ZSM-5 under optimal conditions, the apparent activation energy for benzylation of paraxylene (PX) with BA over SLC400,1S was estimated to be 119 kJ·mol−1. The common by-product of BA route benzylation, dibenzyl ether (DBE), was almost inhibited because of the extraordinary activity of SLC400,1S and the optimized reaction conditions. A 12-run recycling test demonstrated easy recovery and steady reusability of the above lignin-based sulfonated carbon catalyst.
Lactate and isoprene are two common monomers for the industrial production of polyesters and synthetic rubbers. The present study tested the co-production of D-lactate and isoprene by engineered
in ...microaerobic conditions. The deletion of alcohol dehydrogenase (
) and acetate kinase (
) genes, along with the supplementation with betaine, improved the co-production of lactate and isoprene from the substrates of glucose and mevalonate. In fed-batch studies, microaerobic fermentation significantly improved the isoprene concentration in fermentation outlet gas (average 0.021 g/L), compared with fermentation under aerobic conditions (average 0.0009 g/L). The final production of D-lactate and isoprene can reach 44.0 g/L and 3.2 g/L, respectively, through fed-batch microaerobic fermentation. Our study demonstrated a dual-phase production strategy in the co-production of isoprene (gas phase) and lactate (liquid phase). The increased concentration of gas-phase isoprene could benefit the downstream process and decrease the production cost to collect and purify the bio-isoprene from the fermentation outlet gas. The proposed microaerobic process can potentially be applied in the production of other volatile bioproducts to benefit the downstream purification process.
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