POLYMER
·
2015
·
IF 3.562
De-Ming Guo,Teng Fu,Chao Ruan,Xiu-Li Wang,Li Chen,Yu-Zhong Wang
In order to avoid the serious melt-dripping problems caused by conventional phosphorus flame retardants , a new arylene-ether containing monomer named 2,2′-(4,4′-(1,4-phenylenebis(oxy))bis(4,1-phenylene))bis(oxy) diethanol (PBPBD) was synthesized and introduced into the PET main-chain via condensation polymerization. With the incorporation of arylene-ether units, the thermal stability and the char residue from combustion of flame-retardant-element-free copolyesters containing PBPBD (BD x PETs) increased dramatically. However, the crystallinity and melting temperature of these copolymers were lower than the same quantities for PET. Thermal degradation kinetic was investigated using the Ozawa-Flynn-Wall method, which illustrated that the apparent activation energy for decomposition of the copolyesters was enhanced with increasing the conversion and the content of PBPBD. Py-GC/MS results showed that the PBBPD structural units undergo rearrangement reactions at high temperature, and ultimately form conjugated heteroaromatic structures, which lead to the formation of stable char residues with unique “stick-shaped” micro-morphology. Due to these rearrangement reactions, BD x PETs showed an expected flame retardant performance and a reduction in smoke generation during combustion. For example, the LOI value for BD 10 PET was 28.4, and the total smoke production (TSP) was 10.4 m 2 , much smaller than that for PET, 18.8 m 2 . Moreover, melt-dripping was restricted.
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
Journal of Materials Chemistry C
·
2023
·
IF 6.4
Hong Li,Xiyan Li,Jiali Yu,Yadong Li,Zhigang Wang,Feng Bao,Caizhen Zhu,Jian Xu
As ultra large-scale integration (ULSI) circuits develop quickly, traditional polyimide (PI) urgently needs modification due to its high dielectric constant, to make it meet the requirements of ULSI development. In this study, the o-hydroxy polyimide structure was introduced into the PI main chain, and it was confirmed that the thermal rearrangement reaction of o-hydroxy polyimide could increase the molar volume of PI. Based on this property, this study successfully prepared low dielectric polyimide resins and meticulously investigated the effect of the rearrangement ratio on the properties of PI, especially the dielectric properties. The results show that the Dk of PI decreases significantly and the glass transition temperature (Tg) increases significantly with the increase of rearrangement ratio. Among them, it is worth mentioning that PBO-40 has the best performance, presenting a low dielectric constant (Dk = 2.54@10 GHz), low dielectric loss (Df = 0.00585@10 GHz), high heat resistance (Tg = 315 °C, 5% decomposition temperature (N2) Td5% = 509 °C) and low water absorption (Ma = 0.65%). In conclusion, this study provides learnable strategies for the design of high-frequency dielectric PIs.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Shiting Jia,Sai Geng,Mingming Han,Zhen Li,Bolin Zhao,Anyang Shi,Wenyu Xue,Jingyi Lao,Hailong Yu,Qiong Wu,Huihui Wang,Shiwei Liu
In the research of gas-phase Beckmann rearrangement reactions, the employment of modified molecular sieve catalysts has garnered significant research attention. However, the prevalent supported molecular sieve catalysts currently face two formidable challenges. First, the loaded catalytic species are susceptible to detachment, compromising the catalyst’s stability over time. Second, there is a pressing need to enhance the catalytic efficiency to cater to the requirements of modern, highly efficient catalytic processes. Employing a unique microenvironmental framework modification technique, this study has successfully synthesized a silicoaluminophosphate molecular sieve in situ boron doping on the AEL structure. The molecular sieve B-SAPO-11 exhibited a high specific surface area (195.71 m2/g) and enlarged micropore volume (0.065 cm3/g), providing abundant reaction sites and enhancing the efficiency of mass transport and diffusion, respectively, thus giving a favorable microenvironment for the reaction. The catalyst B-SAPO-11 showed an excellent catalytic performance in the gas Beckmann rearrangement reaction of cyclohexanone oxime. The reaction achieved a 96.5% conversion rate and 91.6% selectivity of the desired product under a weight hourly space velocity of 6 h–1 and a temperature of 400 °C. DFT calculations show that adding B forms a synergistic effect with Al, and the dual Bronsted acid catalysis reduces the reaction energy barrier (11.43 kJ/mol). This method has the advantages of high yield of the target product, rapid reaction, and easy catalyst recovery; a new idea was designed to prepare catalysts for gas-phase Beckmann rearrangement reactions.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
STEROIDS
·
2013
·
IF 2.803
Shu-Xiao Feng,Ya-Dong Zhang
One-pot synthesis of an 18-norsteroid compound, 13( R ),14( R )-epoxy-17β-methyl-20( S )-hydroxyl-18-nor-pregna-4-en-3-one has been achieved with peracetic acid/acetic acid under a mild condition, via a proved tandem epoxidation-rearrangement-epoxidation sequence. Its structure was designated on the basis of NMR and X-ray crystallography data.
研究领域:
有机化学
·
药物化学
✓ 已验证
DOI
PubMed
高影响因子
FUEL
·
2022
·
IF 8.035
Xing Gao,Yingying Ding,Lilin Peng,Dan Yang,Xiaoyue Wan,Chunmei Zhou,Wen Liu,Yihu Dai,Yanhui Yang
Aqueous phase hydrogenative rearrangement of furfural (FAL) to cyclopentanone (CPO) via furfuryl alcohol (FOL) has been studied over Pd catalysts supported on H–ZSM–5 zeolites. Pd states, zeolite properties and reaction condition parameters were optimized, affording 98% selectivity and 120 h −1 specific reaction rate over 2% Pd/H–ZSM–5(25) catalyst at 160 °C and 3 MPa H 2 . For hydrogenation of FAL–to–FOL, the activity was related to the Si/Al ratio and acid property of zeolite supports. For hydrogenative rearrangement of FOL–to–CPO, pure H–ZSM–5 zeolite could catalyze single–step conversion with relatively low reaction rate, whereas the presence of Pd sites could achieve multi–step transformation with remarkably increased rate, highlighting Pd–zeolite acid sites synergy. Proton and furanylmethoxy–relevant intermediates were captured with spin trapping electron paramagnetic resonance experiments, and 4–hydroxy–2–cyclopentenone and 2–cyclopentenone were also identified as key intermediates in tandem reaction pathway to produce CPO.
研究领域:
催化化学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2021
·Vol. 139
·期 9
·51731
·
IF 3.125
Mengdi Chen,Jianna Bao,Mingfu Zheng,Xianming Zhang,Wenxing Chen
Melt post-polycondensation (MPP) process is one of manufactures industrially that can efficiently increase the molecular weight of polycarbonate (PC). Herein, the MPP experiments of several PC materials using quaternary ammonium hydroxides and alkali metal compounds as the catalyst in the film state are studied. The reaction products are characterized by Ubbelohde viscometer, DSC, 1 H-NMR, ultraviolet spectrophotometry, advanced polymer chromatography and rotational rheometer. It is found that MPP can effectively improve the intrinsic viscosity of PC. After a certain reaction time at a specific temperature, the number average molecular weight ( M n ) of PC is raised from 19,000 to 54,600 g/mol. Furthermore, the 1 H-NMR results reveal that Fries rearrangement products are produced during the MPP process. Based on the functional group model, a reaction kinetic model, combining the effects of the main melt polycondensation reaction and the Fries rearrangement reaction, is established for the first time. The reaction rate constants at different temperatures and the reaction activation energies of the two PC materials are obtained. This work provides a new reaction kinetics model to guide the MPP process of PC, which contains Fries rearrangement reaction.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2024
·
IF 4.3
Runyu Ma,Yida Zhou,Huifang Wu,Jincong Wang,Xin Yan,Wei Huang,Tianlong Wang,Shutao Xu,Limin Ren
SAPO-37 molecular sieve, characterized by its three-dimensional 12-membered-ring FAU structure, has drawn wide attention due to its unique properties and catalytic potential. However, its susceptibility to framework collapse under low-temperature and humid conditions hinders practical applications, affecting both the reaction performance and sample storage. To tackle this, we utilized aluminum phosphate as a precursor for synthesizing SAPO-37, aiming to modify Si incorporation mechanisms and improve P and Al environments. Solid NMR spectroscopy combined with other techniques proves that the resulting SAPO-37-AP has enriched silicon islands, leading to reduced water adsorption, more reversible structural change, and significantly enhanced stability after low-temperature vapor treatment compared to conventional SAPO-37. Remarkably, SAPO-37-AP, after water vapor treatment, still exhibits superior performance in the liquid-phase Beckmann rearrangement reaction. This approach enhances stability, reduces templating agent amounts, and improves the solid product yield, offering promising practical applications.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Chemical Engineering and Processing-Process Intensification
·
2024
·
IF 3.8
Fengfeng Yan,Kailang Liu,Jingwei Zhang,Tao Zhou,Jinpei Huang,Fajun Wang,Cheng Qi,Jianhong Xu,Sunliang Cui,An Chen
This article developed a microreactor system for the continuous synthesis of Pregabalin. Due to the exceptional heat transfer and mixing capabilities exhibited by the system at the microscale, the Hofmann rearrangement reaction, traditionally requiring multiple sequential steps in batch reactors, can now be efficiently achieved in a consolidated single-step microreactor process. The reaction was executed at a comparatively elevated temperature range of 40–50 °C, and took 5–6 min to achieve the yield of over 90 %, which was a significant improvement compared to the conventional batch reactor method, requiring 7–8 h with a yield of 83 %. The microreactor system utilized its excellent mass and heat transfer performance to reduce the level of the key impurity to below 0.15 % at higher reaction temperatures, meeting the quality requirements for pharmaceutical production. Through experimental research, we determined the effects of reaction conditions like concentration, temperature, and residence time on the reaction rate, as well as key trace impurities.
研究领域:
化学工程
·
制药工程
·
药物合成
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Zhi Hu,Aidi Xie,Chun Chen,Zidan Zou,Yue Shen,Zhen Fu,Yunxia Zhang,Haimin Zhang,Huijun Zhao,Guozhong Wang
Aqueous-phase hydrogenation-rearrangement tandem (AP-HRT) reaction is a green and sustainable route to produce cyclopentanone from bio-based furan compounds. Herein, the ionic liquid was applied as the precursor to synthesize Ni@NP-C catalyst, which contains high dispersed nickel nanoparticles (Ni NPs) encapsulated in the N, P co-doped carbon layer , for the selectivity transformation of furfural towards cyclopentanone. The synthesized Ni@NP-C catalyst can afford 100% FAL conversion and 86.7% CPO yield at 130 °C and 1.5 MPa H 2 within 2 h AP-HRT reaction. The introduction of the electronegative heteroatom on the surface can not only improve the adsorption of reactant but also provide weak Lewis Acid sites for being beneficial to the high selectivity of cyclopentanone. The catalyst displays superior activity, selectivity, and stability in the tandem catalytic system in view of the tunable chemical states of the doped heteroatoms by handily adjusting the pyrolysis temperature.
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
FUEL
·
2018
·
IF 4.908
Jiawei Xie,Xiangwen Zhang,Junjian Xie,Jisheng Xu,Lun Pan,Ji-Jun Zou
Alkyl-diamondoid fuels are attractive for aerospace vehicles due to their high energy density and supreme low-temperature performance. Here we reported a facile route to synthesize alkyl-diamondoids via solvent-free rearrangement of tetrahydrotricyclopentadiene simply catalyzed by acid. The reaction conditions including catalysts, temperature, catalyst dosage, and solvent were optimized. Notably, under the optimal conditions (10.7 wt% cat., 180 °C, 20 h) an extremely high content of alkyl-diamondoids (85.6%) was found in liquid phase, with high carbon yield of alkyl-diamondoids (60.0%) was obtained. The reaction kinetics of rearrangement has been investigated, and the reaction rate constants and apparent activation energies were calculated based on the experimental kinetic data . The resultant diamondoid-based product shows excellent low-temperature performance and a higher energy content than reported diamondoids and widely used JP-10 fuel, thus is superior as a high-energy-density fuel.
研究领域:
化学工程
·
能源科学
·
航空航天工程
✓ 已验证
产品关联
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
Molecular Catalysis
·
2022
·
IF 5.089
Zhiquan Yu,Yan Li,Yunlong Yao,Yao Wang,Ying-Ya Liu,Zhichao Sun,Chuan Shi,Wei Wang,Anjie Wang
A bifunctional Ni 3 P/γ-Al 2 O 3 catalyst with both metal site and Lewis acid site was prepared by an electroless plating method, and applied in hydrogenative ring-rearrangement of furfural to cyclopentanone. The obtained catalyst was characterized by XRD, XPS, XAS, N 2 adsorption-desorption, ICP, TEM, CO chemisorption, NH 3 -TPD and Py-FTIR. The ultrafine Ni 3 P nanoparticles (∼3.8 nm) were highly dispersed in the catalyst. The exclusive Lewis acidity of Ni 3 P/γ-Al 2 O 3 was beneficial for the aqueous-phase hydrogenative ring-rearrangement. The effects of DP time, reaction parameters (temperature, H 2 pressure, solvent composition, and reaction time) on the catalytic performance were investigated. The yield of cyclopentanone was 74.6% at furfural conversion of 99.9% at 180 °C in 1 h over Ni 3 P/γ-Al 2 O 3 catalyst using pure water as the solvent. Moreover, the kinetics of hydrogenative ring-rearrangement of furfural catalyzed by Ni 3 P/γ-Al 2 O 3 was investigated.
研究领域:
催化化学
·
能源化学
✓ 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）