Polymer Chemistry
·
2020
·Vol. 11
·期 34
·5512-5525
·
IF 5.342
Ming Zhang,Yifei Tu,Zibo Zhou,Guozhang Wu
The exo-hydroxyl group (exo-OH) on isosorbide (ISB) has long been asserted as a highly reactive moiety compared with the endo-hydroxyl group (endo-OH). In this study, calculations based on density functional theory and experiments without adding catalysts reveal that endo-OH has strong nucleophilic ability, and in the case of transesterification with diphenyl carbonate, the nucleophilic attack surmounts steric hindrance in rendering endo-OH more reactive than exo-OH. The kinetics of transesterification with different catalysts is investigated to determine the catalytic reactivity and molecular structure evolution. The results show that preferential activation of exo-OH moieties can be achieved either by reducing the coordination ability of catalytic cations (lg β1) or by enhancing the alkalinity of catalytic anions. Despite the low reactivity of exo-OH on ISB monomers, terminal exo-OH on carbonate oligomers exhibits higher reactivity than terminal endo-OH, justifying the experimental fact that ISB-based polycarbonates (ISB-PCs) are mostly terminated by endo-OH. Balancing the reactivity between endo-OH and exo-OH can be promoted by increasing the reaction temperature, thus accelerating transesterification to a high equilibrium constant. These findings help to clarify the mechanism of ISB transesterification and provide new strategies for the synthesis of high-molecular-weight ISB-PCs.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2022
·
IF 9.224
Songlin Wang,Nan Jiang,Jiali Peng,Peng Yang,Chengxing Cui,Hongying Niu,Qiying Zhang,Jianji Wang
Diphenyl carbonate (DPC) has outstanding practical potential, especially as a key building block for the phosgene-free synthesis of polycarbonate (PC) in the chemical industry. The synthesis of DPC from CO2 has been investigated for decades, but exploring highly efficient catalytic systems is still challenging. Herein, an efficient catalytic system for the direct synthesis of DPC from CO2, phenol, and carbon tetrachloride was developed by using a ZnCl2/copper triflate (Cu(OTf)2) composite catalyst. For the first time, high yield and high selectivity were achieved for DPC synthesis under mild conditions, even at atmospheric pressure. Carefully designed control experiments and DFT studies indicated that the synergistic activation of Cu(OTf)2 and its anion complex with ZnCl2 for phenol and CO2 led to a remarkably improved catalytic activity through a Lewis acid-assisted catalysis. This study not only provides a new strategy for efficient preparation of DPC but also offers an effective pathway for better CO2 utilization.
研究领域:
化学工程
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环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 48
·28112-28118
·
IF 3.049
Tao Liu,Xiaoxue Yuan,Gang Zhang,Yi Zeng,Tong Chen,Gongying Wang
In this paper, the Fries rearrangement of diphenyl carbonate (DPC) catalyzed by organotin compounds with different coordination groups was studied for the first time. The electronic effect and steric hindrance of the coordinating groups were discussed with respect to the reactivity of DPC rearrangement. The results showed that both the electronic effect and steric hindrance of the coordinating groups influenced the acidity of the active tin centers and then affected the catalytic performance of organotin as a Lewis acid for the rearrangement of DPC, and the influence of the electronic effect is greater than that of steric hindrance. The catalytic activity is in the order of BuSnO(OH) > Bu2SnO > Bu2Sn(OCOC11H23)2 > BuSnCl3 > Bu3SnOSnBu3 > Bu3SnCl, and Bu2SnO showed the best catalytic activity due to its strong electron absorption effect, small steric hindrance, and good stability. Under the optimum reaction conditions, the conversion of DPC was up to 93%, and the yields of phenyl salicylate (PS) and xanthone (XA) were 62% and 28%, respectively. In addition, a reaction mechanism of DPC rearrangement catalyzed by the organotin compounds was speculated. This research can provide vigorous theoretical data support to control the byproducts produced by DPC rearrangement in the process of DPC synthesis. It also provides a new route for the preparation of PS and XA.
研究领域:
有机化学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Ling Tan,Yufei Huang,Wei Mao,Xiayi Hu,Yangqiang Huang,Hao Chen,Xiao Luo
Diphenyl carbonate (DPC) is a crucial organic chemical intermediate that is widely applied for the synthesis of polycarbonate. The process of transesterification of dimethyl carbonate (DMC) and phenol to produce DPC is promising and is in line with the requirements of green transitions and raw material sustainability. In this work, anatase-layered titanium dioxide (A-TiO2) was prepared and applied for the efficient transesterification of DMC and phenol to synthesize DPC with 10.5% phenol conversion and 87.9% DPC selectivity. The high activity and selectivity of transesterification over A-TiO2 were ascribed via characterizations to the tetracoordinate Ti species and Lewis acid–base sites on the catalyst surface. We further studied the deactivation mechanism of this kind of A-TiO2, and it was found that Ti leaching and the deposition of organic compounds onto the catalyst surface were the major reasons for deactivation during transesterification. This study provides some insights into the design of highly active and selective catalysts for transesterification reactions.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2020
·Vol. 22
·期 8
·2534-2542
·
IF 9.48
Zhencai Zhang,Fei Xu,Yaqin Zhang,Chenhao Li,Hongyan He,Zifeng Yang,Zengxi Li
The conversion of biomass and carbon dioxide to plastics is one of the key solutions to reduce the greenhouse effect and alleviate the petroleum resource depletion. However, there is still a lack of bioderived polymers with high molecular weights and excellent performance and their corresponding green synthesis processes, which limits the potential of bioderived polymers to replace petroleum-based polymers. In this study, an eco-friendly synthetic process for bioderived polycarbonate, catalyzed by amino acid ionic liquids, was developed by utilizing isosorbide (ISO) and diphenyl carbonate (DPC) as reactants, derived from a renewable resource and carbon dioxide, respectively. By using 1-ethyl-3-methylimidazole lysine ([Emim][Lys]) as a catalyst, poly(isosorbide carbonate) (PIC) with the weight average molecular weight of 150 000, the highest reported so far to the best of our knowledge, was synthesized, and the Tg of PIC was up to 174 °C. The reaction mechanism was investigated using nuclear magnetic resonance (NMR) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS), and density functional theory (DFT) calculation. The remarkable catalytic performance was attributed to the fact that [Emim][Lys] could effectively activate the hydroxyl group of ISO and carbonyl group of DPC, and inhibit the formation of cyclic intermediates. Moreover, to overcome the brittleness of PIC, 1,4-butanediol (BD) and 1,4-cyclohexanedimethanol (CHDM) were introduced into PIC, and the copolycarbonate showed excellent Young's modulus, ultimate tensile strength, and elongation at break, which were 979 MPa, 57 MPa, and 145%, respectively, and were comparable to the commercial petroleum-based polycarbonates. Such a process provides further industrial prospects for the next generation of bioderived polycarbonate.
研究领域:
材料科学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2021
·Vol. 59
·期 5
·412-427
·
IF 0
Bin Yang,Qinting Chen,Mengya Ding,Yang Pan,Peng Zhang,Shuqing Wang,Jiasheng Qian,Jibin Miao,Ru Xia,Peng Chen,You Shi,Youlei Tu
Polyvinylidene fluoride (PVDF) films were prepared via thermally induced phase separation (TIPS) using diphenyl carbonate as the diluter in an attempt to disclose the competitive relationship between crystal growth and droplet growth during phase separation process. By varying the quenching temperature different temperature gradient fields were established, which were theoretically evaluated via enthalpy transformation method. The effects of polymer concentration and quenching temperature on evolution of hierarchical morphologies in TIPS films were systematically investigated. According to the morphological characteristics, the cross-sectional morphology of the films with lower polymer concentration ( Φ P = 25%) could be divided into three layers; while that of higher polymer concentration counterpart ( Φ P = 55%) only presented a bi-layered structure. The reason for this could be ascribed to the effect of cooling rate on both crystal growth and droplet growth during TIPS process, which further determined the formation of the hierarchical structure in microporous films. With an increasing quenching temperature, both pore size and porosity of PVDF films increased, accompanied by an improvement on both thermal stability and dynamic mechanical thermal property. The present study could insightfully supply a facile route to fabricate structure-controllable microporous films of crystalline polymers via an appropriate regulation of the TIPS quenching parameters. Graphical Based upon the phase diagram of polyvinylidene fluoride (PVDF)/diphenyl carbonate (DPC) system, the effects of polymer concentration and quenching temperature on the morphologies in thermally induced phase separation (TIPS) films are quantitatively established. TIPS films with lower (below monotectic point) and higher (above monotectic point) polymer concentrations present three-layered and bi-layered hierarchical structures, respectively, primarily originating from the competition between crystal growth and droplet growth during the phase separation.
研究领域:
材料科学
·
高分子工程
·
化学工程
✓ 已验证
产品关联
DOI
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Wentao Zhang,Mi Feng,Shijie Wang,Ming Jiang,Zhichao Shang,Shaojuan Zeng,Xiangping Zhang,Fei Xu
Activating hydroxyl groups in monomers is crucial for preparing high-molecular-weight bioderived polycarbonates. Herein, we developed metal-free deep eutectic solvents (DESs) to activate endo- and exo-hydroxyl groups in isosorbide (ISB) through hydrogen bonding interactions, facilitating the preparation of poly(isosorbide carbonate) (PIC) by melt polycondensation with diphenyl carbonate (DPC). Catalytic evaluation results indicated that the Brønsted acid–base properties of DESs had a greater impact on the Mn of PIC than the molecular size and Lewis acid–base properties. The DESs with a pH value close to 7, a smaller molecular size, and a higher Lewis acidity yielded PICs with a higher Mn. The formation of hydrogen bonds between the DES and the monomer was conducive to the preparation of high-molecular-weight PIC. Among all DES catalysts, the synthesis of PIC catalyzed by choline chloride–ethylene glycol (n:n = 1:2) had the highest Mn, reaching 116,100 g·mol–1. Obtained PIC maintained a high transmittance (>90%) and low yellowness (b* < 0.40). Mechanistic study demonstrated the synergistic activation of ISB and DPC by hydrogen bonding sites of the hydrogen bonding acceptor and hydrogen bonding donor in the DES to prepare PIC. This strategy not only provides a low-cost and efficient method for synthesizing PIC but also offers catalyst design guidance for hydroxyl activation.
研究领域:
材料科学
·
化学工程
·
聚合物化学
✓ 已验证
产品关联
DOI
高影响因子
Carbon Capture Science & Technology
·
2024
·
IF 10.4
Ming Jiang,Xintong Zhang,Mi Feng,Shijie Wang,Zhencai Zhang,Xiangping Zhang,Xingmei Lu,Fei Xu
Using CO 2 -derived dimethyl carbonate (DMC) instead of diphenyl carbonate (DPC) as a carbonyl source for synthesizing bio-based polycarbonates is a green and cost-effective route. However, the synthesis of high-performance polycarbonates via the DMC route remains challenging due to the poor reactivity and selectivity of DMC compared to DPC. Herein, we designed a series of highly active protic ionic liquid (PIL) catalysts for the synthesis of poly(isosorbide carbonate) (PIC) from DMC with ISB. The influences of the structures of anion and cation on the catalytic activity of PILs were systematically studied. Compared with the reported aprotic IL catalysts, the unique reactive hydrogen of the cation in PILs could form a strong hydrogen bond interaction with the carbonyl group of DMC, resulting in higher reactivity of the carbonyl carbon of DMC. Moreover, the nucleophilicity of the anion could be easily tuned by adjusting the p K a value, which effectively realized the balance of the reactivity difference between exo -OH and endo -OH in ISB. Among them, [DBUH][Im] showed the highest catalytic activity, and the weight-average molecular weight ( M w ) and glass transition temperature of PIC reached 55,700 g/mol and 160 °C, respectively. Combined with NMR analyses and DFT calculations, the mechanism that exhibited the synergetic catalytic effect of anion-cation for the polymerization of DMC and ISB was presented.
研究领域:
材料科学
·
聚合物化学
·
绿色化学
·
催化
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）