ACS Sustainable Chemistry & Engineering
·
2023
·
IF 8.4
Zhenlong Song,Yuzhen Hu,Song Li,Jianguo Liu,Xinghua Zhang,Longlong Ma,Lungang Chen,Qi Zhang
Valorizing lignin into valuable chemicals requires the selective breaking of a large number of C–O bonds found in the β–O–4 structure. In this study, we present a one-pot strategy that utilizes two NiO/TiO2 catalysts for the photocatalytic depolymerization of β–O–4 alcohols. The S-1.6%NiO/TiO2 catalyst is used for the dehydrogenation of β–O–4 alcohols at 450 nm. Then, the L-0.8%NiO/TiO2 catalyst is employed for the hydrogenolysis of β–O–4 ketones at 365 nm. Remarkably, the dehydrogenation–hydrogenolysis tandem reaction can be conducted in one pot, which affords high yields of ketones and phenols (up to 89%) from β–O–4 alcohols. Additionally, the L-0.8%NiO/TiO2 catalyst prepared in this article is the smallest NiO/TiO2 photocatalyst reported to date, and the size of NiO in the S-1.6%NiO/TiO2 catalyst is even small enough to enter the lattice of TiO2. We successfully regulated the reaction selectivity by controlling the loading method and the amount of NiO. Our work offers a promising solution for efficiently cleaving target bonds in lignin and provides insights into the design of efficient photocatalysts.
研究领域:
化学工程
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材料科学
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可再生资源转化
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DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 39
·21926-21932
·
IF 2.936
Jie Liu,Xiaodong Fan,Xin Min,Xiuzhong Zhu,Na Zhao,Zichao Wang
This work explores the synthesis of polybutadiene (PB) with high cis-1,4 unit content and narrow molecular weight distribution using a neodymium-based complex, consisting of neodymium(III) trifluoromethane sulfonate (Nd(CF3SO3)3) and coordinated with tris(2-ethylhexyl)phosphate (TOP). The complex's composition and structure are characterized by elemental analysis, XPS and FT-IR. Combined with Al(i-Bu)3, a binary catalyst is obtained and then applied to initiate the polymerization of butadiene. Results indicate that the catalyst system displays a high catalyst activity and the product polymer (PB) features a high cis-1,4 content (98.8%) and a remarkably narrow molecular weight distribution (Mw/Mn = 1.32). Compared with PB initiated by the current well-studied catalyst Nd(CF3SO3)3*3TBP/Al(i-Bu)3, the Nd(CF3SO3)3*3TOP allows significantly narrowing the molecular weight distribution of the PB, because the Nd(CF3SO3)3*3TOP is more easily dissolved in hexane. Therefore, butadiene was polymerized in a homogenous system and each monomer's polymerization was initiated in the single molecular state.
研究领域:
材料科学
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催化化学
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产品关联
DOI
PubMed
高影响因子
PROGRESS IN ORGANIC COATINGS
·
2022
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IF 6.206
Yujie Qi,Xing Huang,Haoqi Zhai,Mengquan Shi,Yuxi Zhang,Yunlong Zhang,Yuxia Zhao
Lignin could generate active free radicals under light irradiation and be directly used as photoinitiator (PI). However, the photoinitiation unit is unclear due to its complex molecular structure. Some previous studies indicate that the photoyellowing of lignin is due to the photosensitivity of Cα‑carbonyl β-O-4 unit in its molecular structure. Herein, four lignin model compounds D2 , S3 , G4 and F4 containing Cα‑carbonyl β-O-4 structure unit were synthesized and characterized. Among them, F4 was obtained by introducing co-initiator 4-(dimethylamino) benzoic acid ethyl ester (EDAB) to the lignin structural unit. The results demonstrated that under 365 nm LED irradiation, the four model compounds all could directly initiate the polymerization of acrylate monomer PEGDA but their photoinitiation efficiency was quite different. F4 exhibited the best photoinitiation performance compared with the other three PIs. As a one-component photoinitiator (PI), the photoinitiation efficiency of F4 was equal to that of a commercial two-component system benzophenone (BP)/EDAB. In addition, when combined with a hydrogen donor triethanolamine (TEOA), the photoinitiation efficiency of the two-component system F4 /TEOA was higher than that of BP/TEOA. Furthermore, the photolysis mechanism of F4 was clarified through identifying the generated active species under light irradiation by electron spin resonance and laser flash photolysis.
研究领域:
材料科学
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有机化学
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产品关联
DOI
高影响因子
JOURNAL OF ORGANOMETALLIC CHEMISTRY
·
2015
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IF 2.173
Shuai Lv,Suyun Jie,Bo-Geng Li
A series of bis{[2-(4,5-diphenylimidazolyl)phenylimino]phenolate}cobalt(II) complexes ( C1 – C4 ) has been synthesized and characterized. Single-crystal X-ray analysis demonstrated that the cobalt center was coordinated by two [NNO – ] ligands and adopted a slightly distorted octahedronal geometry. The type of cocatalyst had a remarkable influence on the catalytic properties and ethylaluminum sesquichloride (EASC) was proved to be more efficient for the polymerization of 1,3-butadiene to produce higher conversion of butadiene and cis -1,4 content of polybutadienes . On activation with EASC, all the cobalt complexes displayed high catalytic activity for the polymerization of 1,3-butadiene. The microstructure determined by FT-IR and NMR spectra demonstrated that high cis -1,4 contents in the resulting polymers were obtained. The conversion of butadiene , microstructure, molecular weight and molecular weight distribution of polybutadienes were influenced by the reaction parameters and ligand structure .
研究领域:
高分子化学
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配位化学
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产品关联
DOI
高影响因子
Frontiers in Bioengineering and Biotechnology
·
2025
·
IF 4.8
Fei Jiang,Zhiming Dong,Xiaoli Lou,Zhuonan Zhang,Li Shuai,Chengke Zhao
Secondary benzyl alcohols (α-OH) in lignin β-O-4 linkages are reactive sites that can trigger undesirable condensation reactions during lignin valorization processes. The selective oxidation of α-OH groups can effectively inhibit lignin condensation reactions, thereby promoting lignin depolymerization. Meanwhile, this approach increases the functionalities, which is beneficial for the design of lignin-derived functional materials. In this study, we report a chemoselective oxidation method using 2-iodoxybenzoic acid (IBX) to selectively convert α-OH groups into ketones. The reaction proceeds under ambient conditions with green DMSO as the sole solvent. Oxidation of β–O–4 model compound (veratrylglycerol-β-guaiacyl ether, VG) revealed exceptional selectivity of this oxidation process, achieving 92% substrate conversion with 90% yield of the corresponding α-ketone product after 48 h. When applied to cellulolytic enzyme lignin, this protocol significantly increased the α-ketone content from 1.2% to 20.5% (relative to total interunit linkages), as identified and quantified by 2D HSQC NMR. The straightforward α-OH oxidation protocol demonstrates significant potential for precise lignin structure modification and rational design of lignin-derived functional materials in sustainable polymer systems.
研究领域:
高分子化学
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绿色化学
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生物质转化
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天然产物化学
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可持续材料
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有机合成方法学
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产品关联
DOI
PubMed
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Jiangwen Guo,Songbo Zhang,Juntao Ren,He Li,Shuwei Wang,Yanming Hu,Guangyuan Zhou
A series of pyridylbenzotriazole iron (II) complexes with general formula (L 2 FeCl 2 ) were synthesized and characterized by IR, ESI-MS, and elemental analysis . Determined by single-crystal X-ray crystallography, complex Fe1 adopts a distorted octahedral geometry. Upon activation with methylaluminoxane (MAO), the activity of the complex for isoprene polymerization decreased as the bulkiness of the substituent at 6-position of the pyridyl ring of the ligand increased. Notably, Fe1 exhibited excellent activity of 4.1 × 10 6 g/(mol (Fe)•h), affording polymers with ultra-high molecular weight ( M n = 2380 × 10 3 g/mol) and narrow distributions ( M w / M n = 1.72). The resulting polyisoprenes possessed predominantly cis -1,4/3,4 alternating structure and short cis -1,4 and 3,4 sequences, irrespective of the reaction conditions, indicating high thermal stability of the catalyst. Moreover, the prepared polyisoprene composite showed higher mechanical properties compared to SSBR-2466 and SSBR-5025 which are the key components of current commercial tread rubber, and had comparable wet traction and superior rolling resistance.
研究领域:
催化
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高分子科学
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材料科学
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产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2025
·Vol. 155
·期 8
·1-13
·
IF 2.4
Zhou Jing,Zhang Gongguo,Si Chongdian,Jin Manman,He Aihua,Niu Qingtao
Series of isoprene polymerizations with different polymerization time were performed by TiCl 4 /MgCl 2 type Ziegler-Natta catalysts. Polymerization kinetics showed catalytic activity had two-stage polymerization feature and the polymer chain microstructure gradually changed from the trans -1,4 and cis -1,4 mixed structure with low molecular weight ( M w ) as well as broad molecular weight distribution ( M w / M n ) at the early stage, to the final high trans -1,4 structure with high M w and narrow M w / M n . The high trans -1,4 units can enhance the tensile strength and hardness of the synthetic polyisoprenes, which are widely used for golf ball cover, medicinal material and shape memory material. Polymers were mainly isolated into Fraction C, D and G by the stepwise isothermal crystallization fractionation method. Fraction C and D had high trans -1,4 content, high trans -1,4-[II] dyad sequence concentration, high trans - trans unit linkage content and high crystallinity, which were generated by high trans -1,4 stereoselective active centers. While G fraction had low trans -1,4 content, low trans -1,4-[II] dyad sequence concentration, low trans - trans unit linkage content and low crystallinity, which were formed by the active center with low trans -1,4 stereoselectivity. The stereoselective transformation of active centers as well as trans -1,4 stereospecific polymerization mechanism of isoprene with TiCl 4 /MgCl 2 -AlEt 3 catalyst system was discussed. Graphical
研究领域:
高分子化学
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有机合成
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材料科学
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催化
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大分子化学
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物理化学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）