JOURNAL OF ORGANOMETALLIC CHEMISTRY
·
2016
·
IF 2.336
Xiang-Xin Zheng,Zhong-Xia Wang
Di(aminomethylpyrrolyl)methane derivatives [2-{5-R′ 2 NCH 2 (C 4 H 2 NH)}] 2 CR 2 ( 2a R = Et, R′ = Me; 2b R = Ph, R′ = Me; 2c R = Ph, R′ = Et; 2d R 2 = 1,1′-biphenyl-2,2′-diyl, R′ = Me; 2e R 2 = 1,1′-biphenyl-2,2′-diyl, R′ 2 = (CH 2 ) 4 ) were prepared through reaction of di(1 H -pyrrol-2-yl)methane derivatives (2-C 4 H 3 NH) 2 CR 2 ( 1a R = Et; 1b R = Ph; 1c R 2 = 1,1′-biphenyl-2,2′-diyl) with formaldehyde and amines. Treatment of 2a with 3 equiv. of ZnEt 2 in toluene afforded trinuclear zinc conplex 3a , while respective reaction of 2b - 2e with 3 equiv. of ZnEt 2 in toluene or THF produced dinuclear zinc complexes 3b - 3e . Each of the complexes was characterized by 1 H and 13 C NMR spectroscopy and elemental analysis . Structures of complexes 3a and 3b were additionally characterized by single crystal X-ray diffraction. Catalysis of complexes 3a - 3e toward the ROP of rac -lactides was evaluated in both toluene and THF. Each complex was active in the catalysis in the presence of benzyl alcohol (BnOH). 3a showed the highest activity in toluene and 3c was the most active in THF. Kinetic study of complexes 3a and 3e was carried out and the results showed that the polymerization catalyzed by 3e /BnOH follows a first-order kinetics, while 3a /BnOH-catalyzed polymerization followed neither first-order nor second-order kinetics.
研究领域:
有机化学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2017
·Vol. 36
·期 2
·149-156
·
IF 1.692
Shi Tong,Zheng Quan-De,Zuo Wei-Wei,Liu Shao-Feng,Li Zhi-Bo
Two types of bifunctional bis(salicylaldimine) ligands ( syn - L and anti - L ) were designed and synthesized to support bimetallic aluminum complexes. Owing to the rigid anthracene skeleton, syn - L and anti - L successfully locked two Al centers in close proximity ( syn - Al2 ) and far apart ( anti - Al2 ), respectively. The distance between two Al centers in syn - Al2 was defined by X-ray diffraction as 6.665 Å, which is far shorter than that in anti - Al2 . In the presence of stoichiometrical BnOH, syn - Al2 and anti - Al2 were both efficient for ring-opening polymerization (ROP) of rac -LA with the former being more active. In the presence of excess BnOH, syn - Al2 showed an efficient and immortal feature, consistent with high conversions, matched M n s, narrow molecular weight distributions and end group fidelity, while anti - Al2 had a much lower activity or even became entirely inactive due to rapid decomposition, indicated by in situ 1 H-NMR experiments of Al complexes with BnOH.
研究领域:
化学
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高分子科学
✓ 已验证
DOI
高影响因子
POLYMER TESTING
·
2015
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IF 2.24
Xinchao Bian,Lidong Feng,Gao Li,Zhiming Chen,Xuesi Chen
An analytical method has been developed to quantitatively determine the residual lactide monomer in polylactide (PLA) using an internal standard method of gas chromatography (GC). The experimental results showed that diphenyl ether (DPE) was an appropriate internal standard for quantitative analysis of residual lactide in PLA. PLA and DPE were dissolved in dichloromethane and precipitated in hexane . At the same time, the residual lactide in PLA and DPE as an internal standard were extracted to hexane from the polymer solution . The resulting solution could be directly injected into a GC system. Therefore, the residual lactide was determined quantitatively using an internal standard method of GC. This method is practical for measuring the residual lactide content in PLA. When the lactide content is 5.0%, the relative standard deviation ( RSD ) of the measurements is 1.7%, while RSD is 6.9% at the low level of 0.4%, which indicates that the method is sufficiently precise.
研究领域:
分析化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2017
·
IF 0
Jie Wang,Guodong Yao,Fangming Jin
With the wide application of lactic acid/alkyl lactates in food, cosmetic, chemical, and biodegradable plastic, much attention has been paid to efficiently convert carbohydrates to lactic acid/alkyl lactates. In this study, an efficient and one-pot Lewis acid-catalyzed conversion of carbohydrates to alkyl lactate in alcohols was proposed. Zn(II) gave the highest yield of ethyl lactates, 47.7% for glucose, 51.7% for fructose and 47.5% for sucrose, respectively, which are the best yields so far. The presence of a small amount of water (about 3%) improved the yield of alkyl lactate and the counter anion had a great effect on the yields of alkyl lactates. According to the intermediates detected and the coordination of Zn(II) with various substrates proved by infrared spectroscopy, the reaction mechanism was proposed and the activation energies were calculated step by step.
研究领域:
生物化学
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催化化学
✓ 已验证
产品关联
DOI
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2024
·Vol. 100
·期 1
·243-254
·
IF 2.8
Cui Quan,Yingying Zhou,Hua Chu,Xiaolei Fan,Ningbo Gao
BACKGROUND Ethyl lactate produced via esterification between lactic acid and ethanol can be used in plastics, polymers and food industries and renowned for its biodegradability and low toxicity. However, lactic acid self-catalyzed esterification presents a slow reaction process, and acid catalysts are needed to improve the catalysis. Homogeneous acid catalysts like H 2 SO 4 are corrosive, as well as being difficult to be seperated from the reaction media; therefore, advanced heterogeneous catalysts are more ideal. In this study, two kinds of heteropolyacid–zeolite catalysts, involving loading silicotungstic acid and phosphotungstic acid onto Y zeolite, were synthesized, characterized using X-ray diffraction, NH 3 temperature-programmed desorption and scanning electron microscopy and analyzed for their catalytic efficiency in the catalytic esterfication. RESULTS Results showed that the Keggin structures of heteropolyacids were retained during the preparation process and strong acid sites of Y zeolite were enriched, which made the main contribution to the esterification of lactic acid and ethanol. Furthermore, the initial-stage reaction rate of esterification was significantly enhanced. During the first hour of esterification, the conversion of lactic acid increased from 18% to 65%. Exp Dec1 index model was employed to determine the activation energies of 60HSiW-Y and 60HPW-Y, which exhibit values of 29.3 and 28.2 kJ mol −1 , respectively. CONCLUSION This study indicates that Keggin structures of heteropolyacids play a key role in the esterification and heteropolyacid–zeolite catalysts can effectively catalyze the esterification. Meanwhile, the results of the kinetic experiments can be of reference significance for large-scale industrial processes involving esterification. © 2024 Society of Chemical Industry (SCI).
研究领域:
化学工程
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 139
·期 45
·e53109
·
IF 3.057
Zheming Zhang,Pingping Jiang,Phyu Thin Wai,Xinxin Gao,Shan Feng,Minjia Lu,Pingbo Zhang,Yan Leng,Qingkui Song,Yong Zhao
Poly(vinyl chloride) (PVC) is one of the most widely applied plastics in the world, with inherent mechanical brittleness and inflexibility in room temperature. With the growing concern for health and safety, especially in some fields (children's toys, food packaging, medical supplies) that require high-safety plastics, there is an urgent need to develop phthalate-free high-performance green PVC products. Herein, by blending novel green oligomeric lactate plasticizers 1, 4-cyclohexane dimethanol oligomeric lactate-levulinate (CDOL-L) and 1,4-cyclohexane dimethanol oligomeric lactate-levulinic acid ketal ester (CDOL-LKE), highly stretchable and highly stable PVC-based plastics were prepared successfully. CDOL-L and CDOL-LKE were synthesized by a green route of esterification and ketalization using biomass as the main raw material, and their structures were jointly confirmed by Fourier transform infrared spectroscopy, 1 H NMR and TOF-MS. Through performance testing, CDOL-L or CDOL-LKE plasticized PVC material were determined to have triple high stability (thermal, mechanical and migration stability) superior to DOP, DOTP and ATBC plasticized PVC. The PVC plasticized by CDOL-L exhibited break at elongation as high as 833.0% at 50 phr addition and 877.1% at 60 phr addition. Moreover, PVC plasticized by 50 phr CDOL-LKE exhibited relatively better thermal stability ( T i ,CDOL-LKE = 271.4°C) for the special ketal structure on the plasticizer. In conclusion, CDOL-L and CDOL-LKE showed potential to substitute traditional plasticizers and pointed a new direction for the preparation of high-performance PVC-based plastics.
研究领域:
材料科学
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化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2020
·
IF 3.862
Yuejia Zhu,Yongzhu Hu,Zhenjiang Li,Bo Liu,Yuanyuan Qu,Zhihao Zhang,Tianfo Guo,Yongqiang Li,Luoyu Gao,Kai Guo
Hydrogen bond donor (HBD) and organic base binary cocatalyst established a gold standard in organocatalytic ring-opening polymerizations (ROPs). In depth probe of the mechanisms revealed that proton abstraction of the acidic H on the HBDs by the bases do occur frequently. A truly simple HBD and Lewis base (LB) cocatalysis, however, was elusive. We proposed genuine HBD/LB cocatalyst for ROPs by introducing 3-amino-1,2,4-benzothiadiazine-1,1-dioxide (ABTD) as a bidentate H-bond donor and triethylamine (TEA) as a mild Lewis base. ROPs of lactide (LA) and trimethylene carbonate (TMC) in solutions at room temperature were success. The mild ROPs produced polylactide (PLA) of predictable molecular weights (from 1.6 to 26.7 kg mol −1 ) and extremely narrow dispersities (Đ 1.01 to 1.06). Furthermore, well-defined diblock copolymers PTMC-b-PLA were synthesized. NMR titration experiments verified exclusive H-bond donor activation of the monomer and TEA activation of the hydroxyl chain end without trace of proton abstraction.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Xiaolong Liu,Jiaxing Zhang,Xue Liu,Kaixuan Yang,Ting Su,Hongying Lü,Peng Wu,Zhiguo Zhu
Catalytic conversions of cyclic ketones into lactones by the Baeyer–Villiger oxidation are particularly attractive for practical applications because catalytic transformations minimize reactant use as well as waste production while simplify processing conditions. Understanding the unique behaviors of highly mesoporous Sn-Beta zeolite catalyst during Baeyer–Villiger oxidation is a challenging research topic. Herein, highly mesopore single-crystalline Sn-Beta zeolite (Sn-Beta-2s) is hydrothermally synthesized via our developed two-step interzeolite transformation strategy. The synthesis mechanism obeys dissolution–recrystallization process, where the degradation step is essential to prepare Sn-Beta-2s zeolite with abundant mesoporous and relatively high hydrophobicity. This single-crystalline Sn-Beta zeolite is adopted to the Baeyer-Villiger oxidation of cyclic ketones as heterogeneous Lewis acid catalyst. Structure-performance relationship reveals that the diffusion performance dominates the product selectivity over three Sn-Beta zeolites. Through the investigation of catalytic mechanism by in-situ FT-IR spectra and DFT calculations, it is found that carbonyl group is activated by zeolitic framework Sn. As for the bulky tert -butyl hydroperoxide oxidant, the reaction can be only triggered on the zeolite surface due to the severe steric constraints within zeolite channels, accounting for the excellent catalytic activity of Sn-Beta-2s zeolite with nanocrystalline nature.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2016
·
IF 3.611
Zhenhuan Xiao,Huacong Zhou,Jianmin Hao,Hailong Hong,Yinmin Song,Runxia He,Keduan Zhi,Quansheng Liu
As the fast depletion of coal resources, exploring the value-added utilization approaches of low rank coals or their components and, in parallel, promoting the conversion of sustainable resources (such as biomass) into useful chemicals are critical issues facing human society. In this work, we used humic acids (HAs), an abundant material in nature (mainly derived from low rank coals), and the transition metal zirconium (Zr) to prepare a novel Zr-containing hydrogen transfer catalyst. The prepared catalyst was applied into the conversion of biomass-derived ethyl levulinate (EL) into gamma-valerolactone (GVL) via hydrogen transfer reaction. Both the preparation conditions of the catalysts and the reaction parameters during the conversion of EL into GVL were systematically investigated. The catalyst was characterized by SEM, TEM, FTIR, powder XRD, and TG analysis. The results demonstrated that the as-prepared catalyst was highly efficient for the conversion of EL into GVL. Under optimized conditions, EL could be completely converted and the GVL yield could reach up to 88.3%. The catalyst could be used at least 11 times without notable changes in both activity and structures, indicating an excellent stability. As far as we know, this is the first work using HAs to prepare Zr-containing catalyst and its application to the conversion of EL into GVL in biomass utilization.
研究领域:
化学工程
·
可再生能源
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
FOOD RESEARCH INTERNATIONAL
·
2022
·
IF 7.425
Wei Jia,Chenna Di,Rong Zhang,Lin Shi
The presence of ethyl carbamate in traditional fermented food is a public health concern for the FDA. The effect of forced photoirradiation (0–150,000 lx) and thermal stress (4, 25, 40 °C) on ethyl carbamate (0–150 μg/L) on physiological characteristics of Baijiu, such as esters content, photochemical degradation, and hydrogen-bond interaction efficiency were monitored by ultra high performance liquid chromatography quadrupole-orbitrap and the dynamic changes by digital foodomics analysis. Furthermore, 748 trace components covering 11 subclasses were identified in Baijiu and 71 esters were screened by Spearman’s correlation, fold changes, P values and VIP values. A forward stepwise multiple regression and discriminant analysis were performed for predicting the content of esters from appearance characteristics obtained by foodomics analysis, reaching R-square values up to 0.91. A reduction of the present variation in ethyl lactate, ethyl caproate, diethyl succinate, ethyl oleate and ethyl linoleate concentration could possibly result in a better understanding of the ethyl carbamate effects. Ethyl carbamate was found to cause esters hydrolysis through inter-molecular interaction in various species of alcoholic drinks . It was demonstrated that the light exposure level and thermal intensity applied for ethyl carbamate-spiked Baijiu samples did not unambiguously influence esters concentration in Baijiu. Future research should focus on moderate light exposure level and thermal stress and should aim at reducing natural ethyl carbamate by more closely controlling the esters content of the ripening degree.
研究领域:
食品科学
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发酵工程
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2021
·Vol. 97
·期 1
·240-253
·
IF 3.174
Zhihang Huang,Songyuan Hao,Hong Yuan
BACKGROUND A novel double acid site solid catalyst (Al-OCS-0.1) having an ordered mesoporous structure was synthesized by grafting sulfonic acid groups on an oxidized ordered mesoporous carbon (OOMC) support and loading 10% Al 2 (SO 4 ) 3 . RESULT Assessments using Field emission scanning electron microscopy, Transmission electron microscopy and X-ray diffraction showed that the OMC structure remained unchanged after the chemical modification and Al 2 (SO 4 ) 3 loading. The Brunauer–Emmett–Teller surface area and average pore size of Al-OCS-0.1 decreased to 181 m 2 g −1 and 7.1 nm after loading Al 2 (SO 4 ) 3 , respectively. Ammonia temperature-programmed desorption (NH 3 -TPD) and Pyridine adsorption infrared spectroscopy (Py-IR) demonstrated that Al-OCS-0.1 had abundant Brønsted and Lewis acid sites. The ammonia desorption of Al-OCS-0.1 increased from 2.0 to 7.2 mmol g −1 after loading Al 2 (SO 4 ) 3 . CONCLUSION The Al-OCS-0.1 was used to catalyze the synthesis of ethyl levulinate from cellulose in ethanol and gave an extremely high yield of 50.8 mol% after 5 h at 200 °C. © 2021 Society of Chemical Industry (SCI).
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
Gels
·
2022
·Vol. 8
·期 11
·714
·
IF 4.432
Yongqiang Gong,Tingting Gu,Tiantian Zhang,Songnan Li,Zhenyu Yu,Mingming Zheng,Yaqing Xiao,Yibin Zhou
An investigation was conducted into the impacts of hydroxypropyl glutinous rice starch (HPGRS) and lactate-esterified glutinous rice starch (LAEGRS) on a dilute solution and gel properties of wheat starch (WS) at different proportions (0%, 1%, 3%, 5%, and 10%). The results of dilute solution viscosity showed that hydroxypropyl treatment of glutinous rice starch (GRS) could promote the extension of GRS chains, while lactate esterification led to the hydrophobic association of GRS chains, and the starch chains curled inward. Different HPGRS: WS and LAEGRS: WS ratios,β> 0 and ∆b> 0, showed HPGRS and LAEGRS produced attractive forces with WS and formed a uniform gel structure. Compared with WS gel, HPGRS, and LAEGRS could effectively delay the short-term aging of WS gels, and LAEGRS had a more significant effect. HPGRS increased the pasting viscosity, viscoelasticity, and springiness of WS gels, reduced the free water content, and established a tighter gel network structure, while LAEGRS had an opposite trend on WS. In conclusion, HPGRS was suitable for WS-based foods with stable gel network structure and high water retention requirements, and LAEGRS was suitable for WS-based foods with low viscosity and loose gel structure.Keywords:hydroxypropyl;lactate esterified;glutinous rice starch;wheat starch;dilute solution;gel properties
研究领域:
食品科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）