Journal of Flow Chemistry
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2021
·Vol. 11
·期 4
·843-853
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IF 2.786
Jiang Xinxiang,Li Guangxiao,Liu Saier,Song Yang,Su Yuanhai
The process characteristics of two main steps in the preparation of 4-nitrobiphenyl (4-NBP) from 4-nitroaniline (PNA) were clearly revealed by applying two continuous-flow microreactors. The first step was the synthesis of 4-nitrobenzene diazonium tetrafluoroborate (4-NBDT) through the diazotization reaction. The reaction temperature, the residence time, and the molar ratio of different reactants were investigated to achieve optimal reaction conditions with the highest yield of 4-NBDT. Notably, the yield of 4-NBDT reached 97% at 25 °C only in 2.3 s with the optimal molar ratio of HBF 4 , NaNO 2 and PNA (i.e., 2.72:1.05:1). The second step was the Suzuki-Miyaura cross-coupling reaction, in which HNO 3 was used to transform the reaction system into a homogeneous state. The effects of mixing performance, the molar percentage of Pd(OAc) 2 to 4-NBDT, the reaction temperature and the residence time on the Suzuki-Miyaura cross-coupling reaction were investigated systematically. With the molar percentage of Pd(OAc) 2 to 4-NBDT of 1 mol%, the yield of 4-nitrobiphenyl (4-NBP) was optimized to 99% in just 13 min at 25 °C. This study demonstrated the excellent potential of utilizing the continuous-flow microreactor for the diazotization and the following Suzuki-Miyaura cross-coupling reaction.
研究领域:
有机化学
·
化学工程
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ACS Omega
·
2024
·
IF 3.7
Haijiao Jia,Mengqi Cheng,Ran Zhao,Pingyi Zheng,Fangfang Ren,Yaqin Nan,Mengting Huang,Youxin Li
An effective palladium nanocatalyst (Fe3O4@SiO2–FPBA–DTPA–Pd) was proposed and prepared, which was immobilized on magnetic silica with ethylenediamine pentaacetic acid and formylphenylboronic acid as biligands. A series of characterizations showed that Fe3O4@SiO2–FPBA–DTPA–Pd was 5–15 nm and contained 1.44 mmol/g Pd2+/Pd0. It was stable below 232.7 °C, and its saturation magnetization value was 21.17 emu/g which was easily recycled by a magnet. Its catalytic ability was evaluated through 7 Suzuki reactions and 15 Heck reactions. Results showed that the yields of 14 reactions catalyzed by Fe3O4@SiO2–FPBA–DTPA–Pd were more than 90%, while were better than those of the other two immobilized Pd catalysts on a single diethyltriamine pentaacetic acid (DTPA) group or boronic acid group. Moreover, Fe3O4@SiO2–FPBA–DTPA–Pd showed good reusability in both Suzuki and Heck reactions. In two model Suzuki and Heck reactions, after seven cycles, its yields were still above 95% without significant loss, which exceeded those of many reported catalysts; therefore, it has great potential in future large-scale industrial production.
研究领域:
化学
·
材料科学
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Xinyi Liu,Zhen Cheng,Nan Chen,Feng Xu,Jian Liu,Lei Ni,Juncheng Jiang
Propylene glycol ethers are a series of fine chemical products with a wide range of applications and are one of the important industrial derivatives of epoxy compounds; the thermal hazards and exothermic mechanism of the reaction process have rarely been investigated in previous studies. In this study, propylene glycol butyl ether (PNB) was prepared by the reaction of propylene oxide (PO) with n-butanol catalyzed by potassium hydroxide in semibatch mode. A Box–Behnken design (BBD) method with four factors and three levels was carried out to optimize the yield and other process parameters of the reaction. The results showed that after optimization, the maximum yield and the minimum system pressure were 85.91% and 1.752 bar, respectively, when the reaction temperature was 110 °C, the alcohol–alkane ratio was 4, the dosing rate was 10 mL/min, and the catalyst concentration was 0.5%. The thermal behavior of the propylene glycol butyl ether synthesis process was investigated by reaction calorimetry. Fourier transform infrared (FTIR) spectroscopy was used to monitor the concentration changes of the reactants and products. Differential scanning calorimetry and adiabatic calorimetry were used to study the thermal stability of the products. Meanwhile, density functional theory calculations were implemented to understand the reaction pathways and associated energies. Furthermore, the thermal runaway risk of the reaction was assessed by the risk matrix method and Stoessel criticality diagram. The results indicated that the risk level was acceptable and the critical class for this reaction was of grade 3. These findings provide guidance for the safe operation of PNB synthesis from PO, which can be used for further scale-up.
研究领域:
化学工程
·
热力学
·
过程安全
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精细化学品
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催化
·
计算化学
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ChemPlusChem
·
2025
·
IF 2.8
Shangzai Wu,Xiaolong Gong,Guojian Ren,Linglong Yi,Qi Zhou,Qinhe Pan
Graphical GA: A stable coordination polymer (HNU-90-Tb) is synthesized by the assembling of 4-carboxytriphenylamine and Tb 3+ , which exhibits highly selective detection of salicylaldehyde by fluorescence quenching with the limit of detection of 0.07 ppm and response time 30 s. The detection mechanism can be contributed to the internal filtration effect and dynamic quenching. Salicylaldehyde, an essential chemical intermediate, is extensively utilized in pharmaceutical and fragrance industries. However, the excessive usage leads to environmental pollution and poses potential risks to human body. Hence, it is urgent to develop the effective sensor for the detection of salicylaldehyde (SAL). Herein, a new terbium(III)-based coordination polymer ( HNU-90-Tb ) is constructed by the assembly of 4-carboxytriphenylamine (HL) with Tb 3 + . Benefiting from the hydrophobic structure of HL, HNU-90-Tb exhibits remarkable stability in aqueous environments and is capable of maintaining structural integrity in pH range of 2–11. Notably, HNU-90-Tb enables quantitative detection of SAL through fluorescence quenching, achieving a low detection limit of 0.07 ppm and a rapid response time of just 30 s. HNU-90-Tb also shows excellent selectivity toward a variety of aldehyde analogs. The detection mechanism can be attributed to the combined inner filter effect and dynamic quenching mechanism.
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