Catalysts
·
2018
·Vol. 8
·期 6
·249
·
IF 3.465
Nani Zhou,Le Shen,Zhen Dong,Jiahong Shen,Lihua Du,Xiping Luo
The preparation of thioesters through the lipase-catalysed transesterification reaction of thiols with vinyl carboxyl esters is described. The reactions were carried out by Lipase TL IM fromThermomyces lanuginosusas a catalyst and performed under a continuous flow microreactor. We first found that lipase TL IM can be used in the reaction of thioester synthesis with high efficiency. Various reaction parameters were investigated including substrate molar ratio, reaction time, and temperature. Maximum conversion (96%) was obtained under the optimal condition of a substrate molar ratio of 1:2 (4-methylbenzyl mercaptan:vinyl esters) at 50 °C for about 30 min. Compared with other methods, the salient features of this work include mild reaction conditions (50 °C), short reaction times (30 min), high yields, and environment-friendliness.Keywords:enzymatic synthesis;thioester synthesis;flow chemistry;microreactor
研究领域:
生物化学
·
有机化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2025
·
IF 3.6
Zelin Zhao,Wenping Li,Qiujie Shan,David J. Young,Zhi-Gang Ren,Hong-Xi Li
We herein disclose a visible-light-induced synthesis of O-aryl esters through the cross-dehydrogenative coupling of aldehydes with phenols using BrCCl3, in which phenolate functions as both a substrate and a photosensitizer. This transition-metal- and photocatalyst-free visible-light-induced esterification is suitable for a wide range of substrates and gives moderate to excellent yields (up to 95%). Mechanistic studies provided evidence of a self-propagating radical reaction involving homolytic cleavage of the aldehydic C–H bond and the formation of acyl bromides. BrCCl3 serves as an oxidant and a hydrogen atom transfer (HAT) agent.
研究领域:
有机化学
·
光化学
✓ 已验证
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Xuan Fei,Yingjie Wang,Penglei Guo,Jinggang Wang,Guyue Wang,Guangming Lu,Weiwei Zhao,Xiaoqing Liu
Polyethylene terephthalate (PET) is one of the most widely used polymers for beverage packaging and fibers, with antimony-based catalysts currently dominating its synthesis. However, concerns about potential safety hazards associated with antimony leaching necessitate the development of environmentally benign catalysts free from heavy metals. In this work, we report the first-time utilization of Ti3C2Tx MXene as a polycondensation catalyst of PET. The intrinsic viscosity of Ti3C2Tx MXene-catalyzed PET could reach 0.78 dL/g within 2.1 h, which demonstrated a superior catalytic efficiency compared to antimony trioxide (Sb2O3). Moreover, Ti3C2Tx MXene exhibited a satisfactory performance not only in PET synthesis but also in the production of polypropylene terephthalate (PPT) and polybutylene terephthalate (PBT), thereby confirming its universality in polyester catalysis. The catalytic activity of Ti3C2Tx MXene in polycondensation reactions was attributed to the presence of strong Lewis acid sites, as supported by surface examinations and computational studies. Notably, Ti3C2Tx MXene-catalyzed PET exhibited satisfied crystallizability, as confirmed by the short crystallization half-time of only 6.9 s at 185 °C, signifying a high crystallization rate. This work highlights the potential applications of this thriving 2D material in polyester catalysis and, more importantly, provides a new perspective for the exploration and design of efficient and environmentally friendly catalyst/nucleation agents for polyester synthesis.
研究领域:
材料科学
·
催化化学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2015
·Vol. 5
·期 5
·2959-2972
·
IF 5.426
Ran Zhang,Li Guo,Chen Chen,Jizhong Chen,Angjun Chen,Xiuge Zhao,Xuerui Liu,Yuhe Xiu,Zhenshan Hou
A novel highly active Mn-doping ceria heterogeneous catalyst (MnOx–CeO2) was prepared and dedicated to the catalytic synthesis of aliphatic carbamates from CO2, aliphatic amines and methanol in one step. The as-obtained catalyst can attain a high yield of carbamate up to 82%, and can also be recycled at least four times through a simple procedure. It was observed that the Mn doping to ceria can alleviate the catalyst deactivation in consecutive catalytic recycles. In this regard, the role of Mn doping in the ceria in the synthesis of the aliphatic carbamates was investigated by means of X-ray diffraction (XRD), Raman spectra, specific surface areas (BET), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), CO2-temperature programmed desorption (CO2-TPD) and in situ diffuse reflectance infrared Fourier transform (DRIFT). The characterization demonstrated that the presence of MnOx in the ceria can not only inhibit the formation of stable carbonate species on the surface of the catalyst but also promote the decomposition/consuming of the carbonaceous species during the synthesis of aliphatic carbamates so as to allow improvement of the recyclability of the catalyst.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
GREEN CHEMISTRY
·
2019
·Vol. 21
·期 11
·3013-3022
·
IF 9.405
Han Hu,Ruoyu Zhang,Jinggang Wang,Wu Bin Ying,Lei Shi,Chenkai Yao,Zhengyang Kong,Kai Wang,Jin Zhu
The melt polycondensation of glycolic acid based copolymers with high molecular weights remains a big challenge. In this work, poly(butylene furandicarboxylate-co-glycolate) (PBFGA) and poly(butylene furandicarboxylate)-b-poly(glycolic acid) (PBF-b-GA) copolyesters were synthesized via melt oligomer polycondensation and melt bulk transesterification, respectively. Herein, melt oligomer polycondensation is a better method with mild preparation conditions and products with higher molecular weights (Mw). The analysis of GPC demonstrated that PBFGAs possessed a Mw of up to 8.95 × 104 g mol−1. The PBFGAs also possessed excellent thermal stability (>320 °C), which endowed the copolymers with a wider processing window than thermolabile PGA. DSC analyses displayed that PBFGA40–PBFGA10 were semi-crystalline materials that melted between 84.5 and 156 °C, while PBFGA50–60 were amorphous. Tensile tests indicated a high elastic modulus of 524–1262 MPa, tensile strength of 16–44 MPa and good elongation at break over 220% of PBFGAs, exceeding most biodegradable packaging materials. The increase of GA units slightly impacted the barrier properties, with reduced CO2 (53×) and O2 (15×) permeability coefficients than those of commercial PBAT films, and also better than those of PET. The hydrolysis of the glycolate was restrained by steric hindrance of furan rings, while in enzymatic degradation PBFGAs displayed obvious weight loss with GA units >20 mol%. With superior thermal, tensile, barrier and degradable properties, PBFGAs have the potential to serve as promising and innovative bio-based polymers for eco-friendly and sustainable plastic packaging.
研究领域:
材料科学
·
环境科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2013
·
IF 2.77
Weidong Zhou,Xiaowei Wang,Bing Yang,Ying Xu,Wei Zhang,Yajie Zhang,Junhui Ji
A series of bio-based poly(butylene adipate-co-butylene furandicarboxylate) (PBAFs) copolyesters were synthesized from 2,5-furandicarboxylic acid (FDCA), adipic acid (AA), and 1,4-butanediol (BDO) through a two-step polycondensation reaction. The copolyesters were characterized by 1 H NMR, GPC , DSC , XRD and tensile tests, and their enzymatic degradation behaviors were also investigated. They were random copolymers whose composition was well controlled and the weight average molecular weight ( M w ) ranged from 54,100 to 76,800 g/mol. By combining the results of DSC and XRD, with increasing FDCA content, PBAFs changed from semi-crystalline polymers to nearly amorphous polymers, then to semi-crystalline polymers again. Specifically, the crystallizability and melting temperature ( T m ) decreased with FDCA content 0–50 mol%, but rose again at FDCA content 75–100 mol%. And, the glass transition temperature ( T g ) increased continuously with increasing FDCA content. Consequently, the tensile modulus and strength decreased but the ultimate elongation increased at lower FDCA content (0–50 mol%), which were converse at higher FDCA content (75–100 mol%). Especially, the P(BA-40 mol% BF) shows outstanding elasticity and rebound resilience. In addition, the influences of FDCA content on the enzymatic degradation by lipase from porcine pancreas were studied in terms of the weight loss and morphological change. At FDCA content of 0–50 mol%, the copolyesters showed biodegradability but only the degradation rate of P(BA-10 mol% BF) was faster than PBA. When the FDCA content were 75–100 mol%, they were actually un-degradable. Thus, depending on their composition, PBAFs might find applications from biodegradable elastomers to thermoplastics .
研究领域:
材料科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER SCIENCE SERIES A
·
2023
·Vol. 64
·期 6
·641-652
·
IF 1
Caixia Zhao,Xu Yuan,Yang Sheng,Zou Guoxiang,Li Jinchun,Dai Junming,Pan Xiaodi
Abstract The novel flexible and resilient poly(butylene succinate- co -butylene oxybisbenzoic) esters were synthesized by a two-step reaction of esterification and polycondensation. The obtained copolyesters were characterized using gel permeation chromatography, 1 H NMR spectroscopy, wide-angle X-ray diffraction, and dynamic thermomechanical analyzer. The mechanical properties were also investigated by the tensile, cyclic tensile, creep and recovery, and stress relaxation testing. The copolyesters have the amorphous nature, excellent flexibility. The elongation at break lies in the range of 510–2870%. In addition, several theoretical models were used to describe the creep and recovery behavior of the copolyesters for a better understanding of the mechanisms.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
CATALYSIS COMMUNICATIONS
·
2019
·
IF 3.674
Wei Wang,Feng Xu,Wenqiao Du,Long Zhang
A facile and efficient one-pot synthesis of methyl carbamate (MC) by urea and methanol was studied using metal modified fluorapatite as a catalyst. M 5 Ca 5 (PO 4 ) 6 F 2 (M 5 FAP, M = Co, Ni, Cu, Zn) was synthesized by co-precipitation. Among the catalysts, Zn 5 Ca 5 (PO 4 ) 6 F 2 (Zn 5 FAP) displayed the higher activity, selectivity and excellent stability after five times of reuse. A possible synthesis reaction mechanism over Zn 5 FAP catalyst was discussed.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2019
·
IF 3.78
Guoqiang Wang,Yin Liang,Min Jiang,Qiang Zhang,Rui Wang,Honghua Wang,Guangyuan Zhou
Six kinds of 2,5-thiophenedicarboxylic acid-based polyesters were synthesized using a two-step melt polycondensation method from 2,5-thiophenedicarboxylic acid (TFDCA) and aliphatic diols . For all polyesters synthesized, weight-average molecular weight was higher than 1.8 × 10 4 g mol −1 . For poly(hexylene 2,5-thiophenedicarboxylate) (PHTF), poly(octylene 2,5-thiophenedicarboxylate) (POTF), and poly(decylene 2,5-thiophenedicarboxylate) (PDTF), they were crystalline polymers due to long crystallizable polyethylene-like hydrocarbon segments in the backbone. However, for poly(2-methyl-1,3-trimethylene 2,5-thiophenedicarboxylate) (PMTF), poly(neopentyl glycol 2,5-thiophenedicarboxylate) (PNTF), and poly(pentylene 2,5-thiophenedicarboxylate) (PPeTF), the melting temperature was not observed. PMTF was a brittle material (elongation at break∼2%). However, other TFDCA-based polyesters were ductile materials (elongation at break>110%). For PNTF, the highest tensile strength (∼63 MPa) and moderate elongation at break (113%) were observed, which were comparable with that of polyethylene terephthalate (PET). The polyesters prepared could be very significant for the development of bio-based polyesters.
研究领域:
材料科学
·
生物基材料
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL PHYSICS
·
2017
·Vol. 30
·期 3
·339-342
·
IF 0.498
Chen Zi-jian,Zhong Wei-qiang,Tang Dong-lin,Zhang Guang-zhao
Metal-free catalysts are preferred during these days in organic synthesis or in polymerizations. Sulfonic acid is reported to be efficient in catalyzing reactions between isocyanates and alcohols. In this work, synthesis of sulfonic acid immobilized organic nanoparticles (nanoacid) and its application in catalyzing urethane formation, are elaborated. The nanoacid can be simply prepared by miniemulsion polymerization with a reactive surfactant, namely sodium 4-((perfluoronon-8-en-1-yl)oxy)benzenesulfonate, followed by an acidification. From the images of scanning electron microscope, the nanoacid obtained is found to be narrowly dispersed and the average diameter is around 90 nm. The measured sulfur content is 0.5%, from which the content of sulfonic acid in the nanoparticles is calculated to be 0.16 mmol/g. When catalyzing urethane formation based on hexamethylene diisocyanate and n -butanol, the nanoacid catalyst exhibits considerable efficiency.
研究领域:
有机化学
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2025
·
IF 4.7
ZhangHe Wang,Chao Zeng,YuHao Wu,ChaoChen Xu,ShengMing Zhang,Peng Ji,ChaoSheng Wang,HuaPing Wang
Polyester (PET) has become the focus of research in the shrink film industry due to its good heat resistance, high transparency, and excellent mechanical properties. In order to improve the shrinkage rate of the film, amorphous PET (PETG) is usually obtained by copolymerization modification using some flexible diols and so on. However, introducing flexible structures reduces the glass transition temperature (Tg) and mechanical strength, and importantly, the gas barrier properties of most PETGs are weak. Here, a series of poly(terephthalic acid-naphthalene dicarboxylic acid-ethylene glycol-neopentyl glycol) (PENTN) were prepared by melt polymerization using different contents of 1,4-naphthalene dicarboxylic acid (1,4-NDA) or 2,6-naphthalene dicarboxylic acid (2,6-NDA). The results show that the introduction of 1,4-NDA does not enhance the Tg of the copolyesters significantly, whereas the Tg of the copolyesters increases linearly with the increase in the content of 2,6-NDA. The Tg of 2,6-PENTNs ranges from 82.2 to 90.5 °C. The crystallization is inhibited effectively due to the neopentyl glycol and exhibits good transparency (>85%) and low haze value (<4%), which results in the preparation of copolyesters that are all amorphous polymers. The differences in the effects of 2,6-NDA and 1,4-NDA on the thermal properties of the copolyesters were analyzed. Meanwhile, the copolyesters were prepared into films, and the gas barrier properties were analyzed in detail. The rheological analysis reveals the free volume of the copolyester is rapidly decreasing with the introduction of the naphthalene group structure. The gas barrier property of the copolyesters can be improved to a high level. This work provides an idea for the functionalized modification of packaging materials.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Reaction Chemistry & Engineering
·
2021
·Vol. 6
·期 11
·2159-2169
·
IF 4.239
Zifei Yan,Chencan Du,Guangsheng Luo,Jian Deng
Glycidyl esters are synthesized through the epoxide ring-opening reactions, and the reaction efficiency must be greatly improved for green and efficient production. In this work, the structure of the side product that caused the decline of selectivity was confirmed by GC-MS and 1H NMR. The formation mechanism of the side product was unraveled, indicating that the relative rates of the parallel competing reactions towards the conversion of an intermediate was a key factor in selectivity. It was found that water as a proton transfer carrier can effectively facilitate the conversion of the intermediate to the target product, thus successfully suppressing the side reactions. The water content of 8–10 wt% in the reaction system was proved to be the optimized range. Relying on the function of water, the ring-opening reaction can be performed at 100 °C instead of 70 °C, and epichlorohydrin (ECH) could be directly fed in the reaction system once instead of dripping for 1 hour. Thus, the reaction time could be reduced from 6 hours to 1 hour, and the product selectivity could be maintained higher than 98%. The industrial production process further proved the effectiveness of this strategy in terms of broadening the temperature range for the highly selective synthesis of glycidyl esters and reducing the scale-up effect.
研究领域:
化学工程
·
绿色化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）