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DNA alkylation promoted by an electron-rich quinone methide intermediate

Chengyun Huang,Steven E. Rokita

《化学科学与工程前沿(英文)》 2016年 第10卷 第2期   页码 213-221 doi: 10.1007/s11705-015-1541-3

摘要: Biological application of conjugates derived from oligonucleotides and quinone methides have previously been limited by the slow exchange of their covalent self-adducts and subsequent alkylation of target nucleic acids. To enhance the rates of these processes, a new quinone methide precursor with an electron donating substituent has been prepared. Additionally, this substituent has been placed to the nascent -methylene group of the quinone methide for maximum effect. A conjugate made from this precursor and a 5'-aminohexyloligonucleotide accelerates formation of its reversible self-adduct and alkylation of its complementary DNA as predicted from prior model studies.

关键词: quione methide     DNA alkylation     reversible covalent reaction     bioconjugation     target-directed modification of nucleic acids    

Benzene alkylation with long chain olefins catalyzed by ionic liquids: a review

QIAO Congzhen, CAI Yonghong, GUO Quanhui

《化学科学与工程前沿(英文)》 2008年 第2卷 第3期   页码 346-352 doi: 10.1007/s11705-008-0045-9

摘要: The introduction of ionic liquids to alkylation process gives a choice for “green production” in the petrochemical and detergent industry. A lot of papers and patents have been published using chloroaluminate ionic liquid as a novel catalyst for alkylation with high reactivity and easy separation from reactants. These included the acidity, characterization, determination and catalysis technologies in batch and continuous operation mode for different scales. According to published data and several results of pilot alkylation,including the authors’ experience,the prospect of chloroaluminate ionic liquids for commercials was also discussed. It has been pointed out that there still are many difficulties and challenges to be overcome for commercial application of the ionic liquid catalyst.

关键词: different     petrochemical     characterization     introduction     chloroaluminate    

ZnZr/HZSM-5 as efficient catalysts for alkylation of benzene with carbon dioxide

《化学科学与工程前沿(英文)》 2023年 第17卷 第4期   页码 404-414 doi: 10.1007/s11705-022-2215-6

摘要: Alkylation of benzene with carbon dioxide and hydrogen to produce toluene and xylene could increase the added-value of surplus benzene as well as relieve environmental problems like green-house effect. In this work, the alkylation benzene with carbon dioxide and hydrogen reaction was proceeded by using the mixture of zinc-zirconium oxide and HZSM-5 as bifunctional catalyst. The equivalent of Zn/Zr = 1 displays the best catalytic performance at 425 °C and 3.0 MPa, and benzene conversion reaches 42.9% with a selectivity of 90% towards toluene and xylene. Moreover, the carbon dioxide conversion achieves 23.3% and the carbon monoxide selectivity is lower than 35%, indicating that more than 50% carbon dioxide has been effectively incorporated into the target product, which is the best result as far as we know. Combined with characterizations, it indicated that the Zn and Zr formed a solid solution under specific conditions (Zn/Zr = 1). The as-formed solid solution not only possesses a high surface area but also provides a large amount of oxygen vacancies. Additionally, the bifunctional catalyst has excellent stabilities that could keep operating without deactivation for at least 80 h. This work provides promising industrial applications for the upgrading of aromatics.

关键词: carbon dioxide     alkylation of benzene     solid solution catalyst     bifunctional catalyst    

Catalytic process modeling and sensitivity analysis of alkylation of benzene with ethanol over MIL-101

Ehsan Rahmani, Mohammad Rahmani

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 1100-1111 doi: 10.1007/s11705-019-1891-3

摘要: A solvothermal method was used to synthesize MIL-101(Fe) and MIL-88(Fe), which were used for alkylation of benzene. The synthesized catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, dynamic light scattering, and BET techniques. Metal-organic frameworks (MOFs) were modeled to investigate the catalytic performance and existence of mass transfer limitations. Calculated effectiveness factors revealed absence of internal and external mass transfer. Sensitivity analysis revealed best operating conditions over MIL-101 at 120°C and 5 bar and over MIL-88 at 142°C and 9 bar.

关键词: MOFs     alkylation     ethylbenzene     catalysts pellet model     kinetic model     sensitivity analysis    

Octane compositions in sulfuric acid catalyzed isobutane/butene alkylation products: experimental and

Lina Liang, Youzhi Liu, Weizhou Jiao, Qiaoling Zhang, Chao Zhang

《化学科学与工程前沿(英文)》 2021年 第15卷 第5期   页码 1229-1242 doi: 10.1007/s11705-020-2030-x

摘要: Octanes in alkylation products obtained from industrial alkylation were studied by batch experiments. More than eight octane isomers were identified and quantified by gas chromatography-mass spectrometry. Based on a classic carbenium ion mechanism, the carbocation transition states in concentrated sulfuric acid catalyzed alkylation were investigated using quantum-chemical simulations and predicted the concentration and octane isomerization products including trimethylpentane and dimethylhexane as well as the formation of heavier compounds that resulted from the oligomerization of octane and butene. The agreement between model calculations and experimental data was quite satisfactory. Calculation results indicated that composition and content of trimethylpentanes in the alkylation products were 2,2,4-trimethylpentane>2,3,3-trimethylpentane>2,3,4-trimethylpentane>2,2,3-trimethylpentane whether the 2-butene or -butene acts as olefin. Heavier compounds in the alkylate were primarily formed by the oligomerization of dimethylhexane with 1-butene. Hopefully, the carbocation transition state models developed in this work will be useful for understanding the product distributions of octane in alkylation products.

关键词: sulfuric acid catalyzed alkylation     carbocation reaction     transition state     octane compositions    

Continuous reaction performances of benzene alkylation with long chain olefins catalyzed by ionic liquid

QIAO Congzhen, LI Chengyue

《化学科学与工程前沿(英文)》 2008年 第2卷 第1期   页码 69-73 doi: 10.1007/s11705-008-0014-3

摘要: Based on a compulsive mixing-reacting-separating-recycling small experimental setup,the continuous reaction performances of benzene alkylation with long chain olefins catalyzed by [BMIM]Cl-AlCl ionic liquid were investigated. Three different situations including normal continuous operation mode (reagent materials), sidetrack feeding from different axial positions along the static mixing reactor (reagent materials) and normal continuous alkylation using industrial paraffin and olefins materials were examined. Even under the relatively hypecritical reaction conditions, the single pass conversion of pure 1-dodecene could reach to nearly 100.0%, and the selectivity of 2-phenyl isomer was higher than 37.7%. Although the positions along the reactor for sidetrack feeding were different, the 100.0% single pass conversion of 1-dodecene was also attained before the outlet of the reactor. The refined industrial olefins as raw material could meet with the requirements of continuous alkylation. The influences of impurities such as di-olefins and non-benzene aromatics on the catalytic activity and stability should be studied further.

关键词: stability     different     hypecritical     compulsive mixing-reacting-separating-recycling     non-benzene    

Alkylation of benzene with propylene catalyzed by FeCl3-chloropyridine ionic liquid

SUN Xuewen, ZHAO Suoqi, LI Hui

《化学科学与工程前沿(英文)》 2007年 第1卷 第3期   页码 292-295 doi: 10.1007/s11705-007-0053-1

摘要: Alkylation of benzene with propylene was carried out with FeCl3-chloro-butyl-pyridine (FeCl-[bpc]) ionic liquid as catalyst to obtain cumene. Significant improvements in propylene conversion and cumene selectivity under mild reaction conditions were attained by modification of the catalyst with HCl. Under 20ºC, 0.1 MPa, reaction time 5 min, mole ratio of benzene to propylene 10:1 and mass ratio of FeCl-[bpc] to benzene 1:100, conversion of propylene can increase from 83.60% to 100.00% and selectivity of cumene can increase from 90.86% to 98.47%. If reaction is carried out in following two stages, the result will be very good. At the initial stage of the reaction, alkylation is the main reaction and a higher conversion of propylene is obtained at a lower temperature. At the later stage of the reaction, transalkylation is the main reaction and selectivity to cumene can be increased by appropriately raising the reaction temperature.

Alkylation of benzene with carbon dioxide to low-carbon aromatic hydrocarbons over bifunctional Zn-Ti

Xiangyu Liu, Yanling Pan, Peng Zhang, Yilin Wang, Guohao Xu, Zhaojie Su, Xuedong Zhu, Fan Yang

《化学科学与工程前沿(英文)》 2022年 第16卷 第3期   页码 384-396 doi: 10.1007/s11705-021-2045-y

摘要: Alkylation of benzene to value-added, high octane number and low toxic toluene and xylenes provides a way to lower benzene content in gasoline pool, and is hence a method to promote fuel quality. On the other hand, CO accumulation in the atmosphere causes global warming and requires effective route for its valorization. Utilization of CO as a carbon source for benzene alkylation could achieve both goals. Herein, alkylation of benzene with CO and H was realized by a series of low-cost bifunctional catalysts containing zinc/titanium oxides (Zn/Ti oxides) and HZSM-5 molecular sieves in a fixed-bed reactor. By regulating and controlling oxygen vacancies of Zn/Ti oxides and the acidities of HZSM-5, benzene conversion and CO conversion reached 28.7% and 29.9% respectively, along with a total selectivity of toluene and xylene higher than 90%. In this process, more than 25% CO was effectively utilized and incorporated into the target products. Moreover, the mechanism of the reaction was analyzed and the course was simultaneously traced. CO was transformed into methanol firstly, and then methanol reacted with benzene generating toluene and xylene. The innovation provides a new method for upgrading of fuels and upcycling the emissions of CO , which is of great environmental and economic benefits.

关键词: carbon dioxide     benzene     alkylation     bifunctional catalyst     mechanism    

Confinement effects in methanol to olefins catalysed by zeolites: A computational review

German Sastre

《化学科学与工程前沿(英文)》 2016年 第10卷 第1期   页码 76-89 doi: 10.1007/s11705-016-1557-3

摘要: Small pore zeolites, containing 8-rings as the largest, are widely employed as catalysts in the process of methanol-to-olefins (MTO). Reactants and products diffuse with constraints through 8-rings and this is one of the reaction bottlenecks related to zeolite micropore topology. Small pore zeolites and silicon-aluminophosphates(SAPOs) containing cavities, where olefins are mainly formed through the hydrocarbon pool (HP) mechanism, are frequently tested for MTO. Shape selectivity of transition states within the side-chain methylation will be reviewed as this is one of the controlling steps of the MTO process, with particular attention to the role of hexamethylbenzene (HMB) and heptamethylbenzenium cation (HeptaMB ), which are the most tipically detected reaction intermediates, common to the paring and side-chain routes within the HP mechanism. The relative stability of these and other species will be reviewed in terms of confinement effects in different cage-based zeolites. The role of the different alkylating agents, methanol, dimethyl ether (DME), and surface methoxy species (SMS) will also be reviewed from the computational viewpoint.

关键词: small pore zeolites     SAPOs     methanol-to-olefins     hydrocarbon pool mechanism     alkylation of polymethylbenzenes    

Hierarchical ZSM-5 zeolite with radial mesopores: Preparation, formation mechanism and application for benzene alkylation

Darui Wang, Hongmin Sun, Wei Liu, Zhenhao Shen, Weimin Yang

《化学科学与工程前沿(英文)》 2020年 第14卷 第2期   页码 248-257 doi: 10.1007/s11705-019-1853-9

摘要: Hierarchical ZSM-5 zeolite with radial mesopores is controllably synthesized using piperidine in a NaOH solution. The piperidine molecules enter the zeolite micropores and protect the zeolite framework from extensive desilication. The areas containing fewer aluminum atoms contain fewer piperidine protectant molecules and so they dissolve first. Small amounts of mesopores are then gradually generated in areas with more aluminum atoms and more piperidine protectant. In this manner, radial mesopores are formed in the ZSM-5 zeolite with a maximal preservation of the micropores and active sites. The optimal hierarchical ZSM-5 zeolite, prepared with a molar ratio of piperidine to zeolite of 0.03, had a mesopore surface area of 136 m ·g and a solid yield of 80%. The incorporation of the radial mesopores results in micropores that are interconnected which shortened the average diffusion path length. Compared to the parent zeolite, the hierarchical ZSM-5 zeolite possesses more accessible acid sites and has a higher catalytic activity and a longer lifetime for the alkylation of benzene.

关键词: hierarchical ZSM-5 zeolite     protective desilication     piperidine     radial mesopores     benzene alkylation    

Novel method for the preparation of Cs-containing FAU(Y) catalysts for aniline methylation

Olga A. Ponomareva, Polina A. Shaposhnik, Marina V. Belova, Boris A. Kolozhvari, Irina I. Ivanova

《化学科学与工程前沿(英文)》 2018年 第12卷 第1期   页码 70-76 doi: 10.1007/s11705-017-1694-3

摘要: Cs-containing FAU(Y)-type zeolite catalysts were prepared by conventional and novel ion exchange procedures followed by incipient wetness impregnation with CsOH. The novel ion exchange procedure involved hydrothermal treatment of NaY zeolite in aqueous solution of CsCl at 140–200 °C for 6–24 h. The samples were characterized by low-temperature nitrogen adsorption, X-ray fluorescence analysis, X-ray powder diffraction, scanning electron microscopy, Na, Al and Cs magic angle spinning nuclear magnetic resonance, CO and NH -Temperature programmed desorption. The results show that hydrothermal treatment at 200 °C allows to obtain higher degrees of ion-exchange (up to 83%) with respect to conventional method giving maximum 66%–69%. Catalytic properties of Cs-containing FAU(Y) were studied in aniline methylation. The yield of -methylaniline is shown to correlate with catalyst’s basicity. The best catalyst performance was achieved over the catalyst with the highest ion-exchange degree impregnated with CsOH. The selectivity to -methylaniline over this catalyst reached 96.4%.

关键词: FAU(Y) zeolite     ion exchange with cesium     aniline alkylation     N-methylaniline    

标题 作者 时间 类型 操作

DNA alkylation promoted by an electron-rich quinone methide intermediate

Chengyun Huang,Steven E. Rokita

期刊论文

Benzene alkylation with long chain olefins catalyzed by ionic liquids: a review

QIAO Congzhen, CAI Yonghong, GUO Quanhui

期刊论文

ZnZr/HZSM-5 as efficient catalysts for alkylation of benzene with carbon dioxide

期刊论文

Catalytic process modeling and sensitivity analysis of alkylation of benzene with ethanol over MIL-101

Ehsan Rahmani, Mohammad Rahmani

期刊论文

Octane compositions in sulfuric acid catalyzed isobutane/butene alkylation products: experimental and

Lina Liang, Youzhi Liu, Weizhou Jiao, Qiaoling Zhang, Chao Zhang

期刊论文

Continuous reaction performances of benzene alkylation with long chain olefins catalyzed by ionic liquid

QIAO Congzhen, LI Chengyue

期刊论文

Alkylation of benzene with propylene catalyzed by FeCl3-chloropyridine ionic liquid

SUN Xuewen, ZHAO Suoqi, LI Hui

期刊论文

Alkylation of benzene with carbon dioxide to low-carbon aromatic hydrocarbons over bifunctional Zn-Ti

Xiangyu Liu, Yanling Pan, Peng Zhang, Yilin Wang, Guohao Xu, Zhaojie Su, Xuedong Zhu, Fan Yang

期刊论文

Confinement effects in methanol to olefins catalysed by zeolites: A computational review

German Sastre

期刊论文

Hierarchical ZSM-5 zeolite with radial mesopores: Preparation, formation mechanism and application for benzene alkylation

Darui Wang, Hongmin Sun, Wei Liu, Zhenhao Shen, Weimin Yang

期刊论文

Novel method for the preparation of Cs-containing FAU(Y) catalysts for aniline methylation

Olga A. Ponomareva, Polina A. Shaposhnik, Marina V. Belova, Boris A. Kolozhvari, Irina I. Ivanova

期刊论文