CATALYSIS COMMUNICATIONS
·
2013
·
IF 2.915
Y.-W. Sun,X.-H. Lu,X.-L. Wei,D. Zhou,Q.-H. Xia
Co 2+ -exchanged zeolite catalysts were prepared by an ion-exchange route and firstly applied in the N -alkylation of aromatic amines with alcohols to imines. For the N -alkylation of aniline with benzyl alcohol, the aniline conversion of 89.8 mol% with an imine selectivity of 100% was achieved over Co-13X at 433 K under optimal conditions. The results showed that many factors including the Co loading, the support, the temperature, the alkali, could influence the reactions. Investigations carried out by XRD, SEM and recycling studies indicated that the Co-13X catalyst still remained porous structures of 13X zeolite and possessed a stable catalytic activity.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2020
·
IF 3.862
Bingqi Li,Shengping You,Wei Qi,Yuefei Wang,Rongxin Su,Zhimin He
Lignin sub-micro spheres have drawn wide attention because of their biodegradable, biocompatible and large surface area. However, the formation of stable and tunable lignin micro/nanospheres are limited by lignin source, preparation method and aggregation characteristics. Amphiphilic lignin tends to form aggregates in water under two tunable forces, including hydrophobic and hydrophilic interactions. Herein, we rationally modify the amphiphilic interface of corncob lignin (CL) with the chemical modification of four types of n-alkane to tune its amphiphilicity. Four alkylated CLs with similar chemical properties, but different interfacial interactions have been successfully synthesized. We find that n-alkane and aromatic skeleton contribute to the hydrophobic interactions to induce the aggregation of CL. The results show that modulating the hydrophobic and hydrophilic interactions can successfully promote the formation of CL sub-micro spheres (CLS) with tunable surface properties. The higher hydrophobic interactions and longer alkyl chain, the smaller size of CLS. The average diameters of CLS can be reduced from 400 nm to 100 nm by increasing the length of alkyl chain. What’s more, CLS can disperse stably in water for 60 days and in acid-base environment at pH 4–10 for 30 days.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Weikun Chen,Xiao Fu,Xiaoying Liu,Linmin Ye,Youzhu Yuan
N -alkylated piperazines can be synthesized by the thermal catalytic alkylation of piperazine with alkyl halides or alcohols in the presence of supported metal catalysts. However, these processes either discharge large amounts of waste or require harsh conditions. Here, we report the results of N -alkylation of piperazine with lower alcohols (methanol, ethanol, and propanol) without external hydrogen addition at room temperature in the presence of a TiO 2 -supported Pd catalyst (Pd/TiO 2 -P) prepared by photodeposition method. Compared with the catalysts prepared by the conventional chemical reduction or hydrogen reduction, the Pd/TiO 2 -P catalyst showed the highest conversion of piperazine and the best selectivity to N -alkypiperazines. The mechanistic studies indicated that this phenomenon occurs via tandem photocatalytic reactions involving alcohol dehydrgenation to aldehyde, aldehyde condensation with piperazine to enamine, and enamine hydrogenation to N -alkylated piperazines. Considering the experimental results of methanol isotope kinetics, the α-C–H cleavage of methanol to form hydroxymethyl radical (·CH 2 OH) was proven to be the rate-determining step in the N -alkylation reaction of piperazine with low carbon alcohols. The characterization and control experiments revealed that the size of Pd nanoparticles and the valence of Pd species were vital to the reaction. The Pd/TiO 2 -P catalyst with an average of 2.5 ± 0.5 nm Pd particles and approximately 68% Pd 0 species on surfaces presented the highest activity for the photocatalytic tandem reactions of methanol dehydrogenation and enamine hydrogenation.
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
JOURNAL OF CATALYSIS
·
2019
·
IF 7.723
Jing Wang,Tianqinji Qi,Zhibin Li,Wei She,Xuewei Li,Jingfang Li,Pengfei Yan,Weizuo Li,Guangming Li
Three novel N-doped carbon supported Co/Co 3 O 4 catalysts, namely, Co@CN- hmta , Co@CN- larg and Co-Co 3 O 4 @CN- bipy , with sheet-, worm-, honeycomb-like morphologies respectively, have been fabricated by the pyrolysis of well-defined coordination polymers (CPs). Upon the as-prepared catalysts were applied for the reaction of N-alkylation of nitroarenes with ethanol, a direct two-step tandem reaction is realized, in which the Co@CN- hmta delivers 100% conversion/selectivity of N-ethylaniline/N , N-diethylaniline from the direct N-alkylation of nitroarenes with ethanol. The kinetic studies were conducted to confirm that the N-alkylation of aniline with ethanol is the rate-determining step in the two-step tandem reaction. The SEM/EDX, XRD, Raman, TEM, XPS, and CO 2 -TPD characterization results have revealed that sizes and dispersion of metallic Co, amount of structural defects and surface Lewis basicity towards three catalysts can be tuned by changing the structures of Co-based CPs designed by different organic linkers, which may also help to understand the preparation of industrial catalysts on a molecular level. The optimized Co@CN- hmta catalyst is easily recycled by using the external magnet for successive reuses without any loss in both activity and selectivity. To the best of our knowledge, this is the first carbon-nitrogen species supported Co/Co 3 O 4 catalysts derived from the CPs, which could effectively catalyzed the N-alkylation of nitroarenes with ethanol to produce the secondary amines and/or tertiary amines. This low-cost, recyclable and easy scale-up N-doped carbon supported catalyst may be of potential application in various heterogeneous catalytic reactions.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2017
·Vol. 28
·期 9
·1107-1114
·
IF 1.907
Yuchen Huang,Longbao Feng,Yi Zhang,Liumin He,Changyong Wang,Jiake Xu,Jianping Wu,Thomas Brett Kirk,Rui Guo,Wei Xue
Chitosan (CHI) is a versatile biological material that is well known for its hemostatic properties. This preliminary study evaluated several self-assembling hydrophobically modified chitosan (HM–CHI) sponges to determine their efficacy on hemostasis . Fourier transform infrared (FT-IR) spectroscopy was used to determine the successful graft of dodecyl groups onto the nitrogen atoms of CHI molecules. A platelet aggregation assay revealed that HM–CHI accelerated the platelet aggregation rate. Fluorescence spectroscopy showed that the HM–CHI changed the structure of fibrinogen in blood. Activated partial thromboplastin time, prothrombin time, fibrinogen time, and thromboelastographic assays were used to explore the effect of HM–CHI on the autologous blood coagulation pathway. Finally, a hemostatic sponge was made with HM–CHI and freeze-dried zeolite composite film and was applied to the rat femoral artery hemostasis model. A hemostasis time of 86 ± 5 sec was achieved, which was significantly better than the one composed with pure CHI. The experimental results of the HM–CHI hemostatic materials are inspiring and will encourage the research and development of such materials. HM–CHI may be a strong candidate as a safe and effective hemostatic material. Copyright © 2017 John Wiley & Sons, Ltd.
研究领域:
生物材料学
·
医学工程
·
药理学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2020
·
IF 5.006
Sishi Zhang,Jie Xu,Hongmei Cheng,Cuicui Zang,Bin Sun,Heyan Jiang,Fengxia Bian
Atomic economy, non-toxicity, harmlessness and multidirectional selectivity advocated by green chemistry have increasingly become a hot and difficult research topic. Herein, we present a highly efficient, one-pot tandem and easy-to-operate method through which we could directly produce a broad range of multi-directional selective hydrogenated amines or N-alkyl aliphatic amines using aromatic nitro compounds as raw materials. Ru/LDH with characteristics of layered mesoporous structure, well dispersed small Ru nanoparticles and LDH stabilization to the Ru NPs was employed as the catalyst. It is remarkable that multi-directional superb chemoselectivity to aromatic amines, alicyclic amines as well as N-alkyl aliphatic amines could be achieved with excellent catalytic activity and recyclability by tuning reaction conditions over 5wt%Ru/LDH-2. Additionally, this catalytic system also exhibited attractive activity and multi-directional chemoselectivity in the hydrogenation of quinoline and its derivatives with solvents of different polarity. Chemoselectivity to 5,6,7,8-tetrahydroquinoline derivatives could reach as high as 95.6 %.
研究领域:
催化化学
·
绿色化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Guangyuan Zhao,Danxin Hu,Shenghu Zhou,Jian Zhang,Lei Wang
A series of supported highly dispersed CuNi alloy nanocatalysts were fabricated by a coprecipitation method for the N-alkylation of aniline with 2,5-dihydroxymethylfuran under base-free conditions. Various characterizations and catalytic experiments were carried out to systematically investigate the relationship between the catalytic performance and synthetic parameters, such as calcination temperatures, reduction temperatures, and catalyst compositions. The optimized Cu3/17Ni6/17Al8/17O catalysts show good selectivity for the N-alkylation of aniline with 2,5-dihydroxymethylfuran under mild reaction conditions. This work broadens the application of non-noble bimetallic nanocatalysts for N-alkylation reactions and opens new opportunities to synthesize useful HMF derivatives and other valuable biobased chemicals.
研究领域:
化学工程
·
催化化学
·
生物质化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2021
·
IF 6.953
Mengya Li,Hui Liu,Jie Liu,Ying Pei,Xuejing Zheng,Keyong Tang,Fang Wang
A highly hydrophobic and self-recoverable sponge was prepared with cellulose nanofibrils (CNFs), N-alkylated chitosan (NCS), and poly (vinyl alcohol) (PVA), which was then endowed with hydrophobic properties via simple thermal chemical vapor deposition (CVD). The three-dimensional (3D) interconnected microstructure of the prepared CNF/NCS/PVA sponge was found to have 96% porosity, ultra-low density (16.61–50.91 mg/cm 3 ) and high hydrophobicity (water contact angle of 147°), which can absorb various organic solvents with an absorption capacity of 19.05–51.08 times of its original weight. Besides, the sponge could bear 80% strain and be cyclically compressed 50 times under the strain of 50%. The sponge can effectively separate oil/water mixtures and water-in-oil emulsions with high separation efficiency and fluxes. Moreover, the sponge could keep its good stability in various acidic, saline and mechanical abrasion conditions. The green preparation and good separation efficiency suggest a potential application of recyclable and versatile CNF/NCS/PVA sponges in oil/water separation.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Tao Liu,Shuhan Liu,Yihan Shi,Zhuoran Zhang,Sheng Ding,Kexin Hou,Wen Zhang,Xin Meng,Fan Li
The ideal hemostatic agents should be able to stop bleeding quickly and avoid secondary bleeding caused by adhesion with blood clots during dressing change. Herein, a hydrophobic electrospun nanofiber membrane was prepared for achieving hemostasis , rationally targeting both attributes, via doping N -alkylated chitosan ( N -CS) grafted with octadecyl into chitosan/polyethylene oxide (PEO). In vitro and in vivo coagulation tests showed that CPNs doped with small amounts of N -CS (CPN31) could significantly shorten hemostasis time and promote the formation of more stable and stronger blood clots. In particular, the whole blood clotting time of CPN31 (58.8 ± 2.2 s) was significantly lower than that of chitosan/PEO (CPN0) nanofiber membrane (67 ± 3.5 s) and the medical sterile gauze (86.7 ± 0.6 s). Furthermore, due to the hemophobic nature of CPNs, blood wetting of the dressing was severely limited and blood can coagulated at the site of liver injury in rats, thus reducing blood loss and allowing rapid removal of the dressing without triggering secondary hemorrhage. The CPN31 exhibited excellent hemostasis properties, easy to remove, blood compatibility, biocompatibility and promoting fibroblast proliferation properties. This hydrophobic CPNs is a promising biological adhesive for hemorrhage control.
研究领域:
生物医学工程
·
材料科学
·
医学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2023
·Vol. 13
·期 17
·5058-5070
·
IF 5
Zihan Lv,Zeng Hong,Chao Qian,Shaodong Zhou
Pt–Pd alloy nano-catalysts supported on TiO2 were developed to enable efficient light-induced photocatalytic N-alkylation of amines with alcohols. Various techniques such as BET, XRD, XPS, HRTEM, UV-vis DRS, and PL analysis were utilized to characterize the catalysts. The photocatalytic mechanism was discussed based on observation as well as theoretical calculation. It was found that Pt serves as a hydrogen shuttle, extracting hydrogen from alcohols to Pd for subsequent hydrogenation on the Pd site. By changing the Pd/Pt ratio, it is feasible to tune the reaction rates of methanol dehydrogenation and imine hydrogenation simultaneously, resulting in an efficient N-alkylation reaction. As a result, the optimum catalyst Pd1Pt1/TiO2 exhibits excellent catalytic performance which is superior to the previously reported ones in terms of both the catalytic efficiency and the production capacity.
研究领域:
化学
·
材料科学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2018
·Vol. 9
·期 2
·286-301
·
IF 5.365
Mengyuan Zhang,Shipeng Wu,Longchun Bian,Qiue Cao,Wenhao Fang
Ce–Ni mixed oxides with different Ni/Ce molar ratios, promoted by a rather low amount of Pd (0.2 wt%), were prepared by a simple one-pot precipitation method. The thus-synthesized CeNiXOY and Pd–CeNiXOY catalysts were applied respectively to the direct N-alkylation of amine and alcohol via oxidative coupling, under O2 in the absence of basic additives. The CeNiXOY catalyst could provide a >99% yield of imine in the model alkylation reaction of aniline with benzyl alcohol at 100 °C. The Pd-promoted Pd–CeNiXOY catalyst surprisingly showed an enhanced imine yield (>99%) at a mild temperature of 60 °C. This catalyst exhibited good reusability, and moreover, demonstrated high performance towards imine synthesis from various amines with alcohols. The presence of Pd species and the Ni/Ce molar ratio showed a synergistic impact on the conversion of aniline, as well as on the product selectivity, which was believed to be related to the improvement on the intrinsic activity of the oxidation of benzyl alcohol to benzaldehyde. Various physicochemical techniques, including ICP-MS, XRD, N2 adsorption–desorption, UV-Raman, H2-TPR, TEM, EPMA and XPS, were employed to study mainly the composition, structure and redox properties of the catalysts. The proportion of Ce3+ species and oxygen vacancies, which can be manipulated by the Ce–Ni redox system and the interaction between Ce and Ni, was crucial to the selective activation of alcohols in the presence of reactive amines. The activation of alcohol on the highly reactive Pd0 species was the other crucial factor.
研究领域:
催化化学
·
材料科学
·
绿色化学
✓ 已验证
DOI
高影响因子
Journal of Coatings Technology and Research
·
2019
·Vol. 17
·期 2
·345-359
·
IF 1.584
Peng Zhongkang,Tang Liuyan,Yuan Ye,Qu Jinqing
Abstract A series of N -alkylated aminosulfonic acids (NASAs) were synthesized with 1,4-butane sultone and primary amines and then reacted with hexamethylene diisocyanate trimer to obtain water-dispersible polyisocyanates (WDPs). Two-component waterborne polyurethane (2K-WPU) coatings were finally prepared by the reaction of WDPs and aqueous hydroxyl resins. The structures and properties of WDPs and 2K-WPU coatings were characterized. The effects of the categories and amounts of NASAs on the properties of WDPs and 2K-WPU coatings, including viscosities, water resistance and transparency, were investigated. The results showed that the average molecular weights and viscosities of the WDPs increased with the increase in the amounts and molecular weights of NASAs. 3-(Cyclohexylamino)-1-propanesulfonic acid possesses a high molecular weight, resulting in low-concentration –SO 3 per mass, so a high concentration up to 3.5 wt% was needed to meet water-dispersible requirements. On the other hand, 3-isobutylamino-1-propanesulfonic acid (IBAPS) has high-concentration –SO 3 per mass and only a low concentration (2.5 wt%) was required to offer satisfactory water dispersibility. 2K-WPU film cured by IBAPS-WDP displayed high gloss, good transparency and excellent water resistance owing to suitable steric hindrance and high content of –SO 3 H per mass. Graphic abstract
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）