CHINESE CHEMICAL LETTERS
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2014
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IF 1.178
Cheng-Xi Zhang,Yu-Yuan Deng,Yi-Yang Zhang,Po Yang,Yi Gu
To study the synthesis of 3,4-dihydro-2 H -3-phenyl-1,3-benzoxazine (benzoxazine), the reaction paths of phenol, aniline and formaldehyde were investigated by analyzing the synthesis crude products. With the aid of high-performance liquid chromatography (HPLC), chromatographic column and preparative HPLC, seven compounds originated from the crude products were obtained and their chemical structures were elucidated. Possible reaction paths are proposed based on these compounds. Results show that N -hydroxymethyl aniline (HMA) derived from the reaction of formaldehyde and aniline is probably the key intermediate during the reaction. HMA can react with itself or other reactants to form other intermediates, such as 1,3,5-triphenyl-1,3,5-triazinane and 2-((phenylamino)methyl)phenol, and further form benzoxazine and byproducts.
研究领域:
有机化学
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合成化学
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DOI
高影响因子
Catalysts
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2022
·Vol. 12
·期 11
·1328
·
IF 4.501
Liang-Qiu Huang,Zhi-Jun Diao,Bo Chen,Qing-Pan Du,Kai-Yang Duan,Si-Jia Zhao
Efficient depolymerization of C–O linkages is essential for converting lignin into fuels and higher value-added chemicals. In this work, CoRuP/SiO2, an amorphous Ru-Co phosphide composite, was fabricated for the efficient hydrogenolysis of ether linkages. The 4–O–5 andα–O–4 linkages containing lignin-related compounds, such as diphenyl ether, benzyl phenyl ether, 3-methyl diphenyl ether, and dibenzyl ether, are selected as representatives of linkages in lignin. Under mild conditions, Ru-containing metallic phosphides have high-performance for the catalytic depolymerization of C–O linkages. Compared with other catalysts, CoRuP/SiO2shows an outstanding selectivity for benzene and excellent efficiency in depolymerizing diphenyl ethers, yielding only a small amount of by-products. Furthermore, the total acidity shows a linear relationship with the hydrogenolysis reactivity in cleaving aromatic ether bonds. The mechanisms for the catalytic hydrogenolysis of 4–O–5 andα–O–4 bonds over CoRuP/SiO2are proposed. Moreover, two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance spectroscopic analysis demonstrates that CoRuP/SiO2could effectively depolymerize C–O bonds of lignin. These dominant hydrogenolysis products from lignin have excellent potential in the production of high value-added drugs or pharmaceutical intermediates. The hydrogenolysis of lignin can be a highly efficient alternative to the existing method of lignin utilization.Keywords:hydrogenolysis;C–O linkages;metallic phosphides;reaction pathway
研究领域:
化学工程
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可再生能源
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产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2021
·
IF 19.503
Wei Guo,Yao Qin,Cheng Liu,Binbin Guo,Junhua Zou,Zenghong Xie,Ling Wu
This work reports the rapid and effective photocatalytic dechlorination of 3,3′,4,4′-trtrachlorobiphenyl (PCB77) with highly dispersed Pd nanoclusters loaded two-dimensional (2D) TiO 2 (B) nanosheets (Pd/TiO 2 (B)) under visible light irradiation, achieving a dechlorination efficiency of 100 % with H 2 O used as an H-donor source. The ultra-thin TiO 2 (B) nanosheets provide a good platform for studying the dechlorination intermediates/pathways of PCB77 at the molecular level. It is proved that the dechlorination of PCB77 is a stepwise process, in which chlorines at the para positions are much more susceptible than those at the meta positions due to the activation of the C Cl bond in the presence of Pd nanoclusters. Furthermore, in-situ FTIR results of D 2 O absorption suggest that the TiO 2 (B) nanosheets with abundant surface defects greatly promote the activation of water molecules via the formation of surficial complexes by hydrogen bonds. Finally, a synergistic mechanism is proposed for photocatalytic dechlorination of PCB77 over Pd/TiO 2 (B). The study provides an efficient method for complete dechlorination of PCB77 and an in-depth understanding photocatalyzed dechlorination reaction mechanism at the molecular level, which may extend to other photocatalytic dehalogenation reactions of halogenated pollutants.
研究领域:
环境科学
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材料科学
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化学工程
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产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2024
·
IF 8.2
Rui Yu,Yunkun Qian,Yanan Chen,Yijun Shi,Jun Guo,Dong An
Dichloroacetonitrile (DCAN) is an emerging disinfection by-product (DBP) that is widespread in drinking water. However, the pathway for DCAN formation from aromatic amino acids remains unclear, leading to a lack of an understanding of its explicit fate during chloramination. In this study, we investigated the specific formation mechanism of DCAN during the chloramination of phenylalanine based on reaction kinetics and chemical thermodynamics. The reason for differences between aldehyde and decarboxylation pathways was explained, and kinetic parameters of the pathways were obtained through quantum chemistry calculations. The results showed that the reaction rate constant of the rate-limiting step of the aldehyde pathway with 1.9 × 10 −11 s −1 was significantly higher than that of decarboxylation (3.6 × 10 −16 s −1 M −1 ), suggesting that the aldehyde pathway is the main reaction pathway for DCAN formation during the chloramination of phenylalanine to produce DCAN. Subsequently, theoretical calculations were performed to elucidate the effect of pH on the formation mechanism, which aligned well with the experimental results. Dehydrohalogenation was found to be the rate-limiting step under acidic conditions with reaction rate constants higher than those of the rate-limiting step (expulsion of amines) under neutral conditions, increasing the rate of DCAN formation. This study highlights the differences in DCAN formation between the decarboxylation and aldehyde pathways during the chloramination of precursors at both molecular and kinetic levels, contributing to a comprehensive understanding of the reaction mechanisms by which aromatic free amino acids generate DCAN.
研究领域:
环境科学
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化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2021
·
IF 5.316
Zhihua Tian,Fushuo Wu,Peiying Hu,Jianxiang Ding,Yan Zhang,Peigen Zhang,ZhengMing Sun
The properties of MAX phases can be fine-tuned to meet some particular applications via solid solution route, and the feasible preparation of the MAX solid solutions is a prerequisite for their applications. Ti 3 (Sn x Al 1−x )C 2 solid solutions over the whole composition range (x = 0–1) are synthesized by pressureless sintering, and characterized by XRD and SEM. The composition and crystal structure of representative Ti 3 Sn 0.8 Al 0.2 C 2 are examined by HRTEM, HAADF and EDS associated with STEM, and thus the Sn-rich Ti 3 (Sn x Al 1−x )C 2 solid solution is confirmed. Combined with means of thermal analysis, the reaction path for the formation of the Sn-rich Ti 3 (Sn x Al 1−x )C 2 solid solution is explored. Solid solutions are found to form with TiC as the nucleus and grow by reacting with Ti–Sn/Ti–Al intermetallic compounds . This work proves that the Ti 3 (Sn x Al 1−x )C 2 over the whole composition range, in particular, the Sn-rich end of this series of solid solutions can be obtained by the simple pressureless sintering, and would enable the fine manipulation of the composition of these typical MAX solid solutions for technologically important applications.
研究领域:
材料科学
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固体物理
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
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2018
·
IF 4.427
Lingfei Ma,Chaoyi Wang,Haipu Li,Fangyuan Peng,Zhaoguang Yang
Geosmin (GSM) and 2-methylisoborneol (2-MIB) are two common odor compounds in drinking water . In this paper, the performance of UV/chlorine was compared with that of chlorine and UV to degrade GSM (100 ng L −1 ) and 2-MIB (100 ng L −1 ) in water. UV/chlorine was further exploited, and a steady-state kinetic model was used to conduct a detailed study on efficiency, rate, reactive species and pathway. The results showed that UV/chlorine greatly could improve the removal ratio to 90% within 5 min, from approximately 20% with only UV or dark chlorine in 60 min. The removal ratio and rate depended on UV light intensity , free chlorine dosage, reaction time and water quality parameters (e.g. pH, concentrations of HCO 3 − and Cl − ). Among these factors, the first two obviously could accelerate the rate and increase the ratio. The degradation was also significantly improved in an acidic condition, while alkaline conditions and HCO 3 − had inhibitory effects, and Cl − created no difference. Contributions of OH and Cl to the degradation of 2-MIB and GSM were further revealed, and OH was found to be the most important reactive species. In the UV/chlorine process, 6 degradation byproducts of 2-MIB, including 1 alcohol, 2 ketones, and 3 olefins , were identified, and 14 degradation byproducts of GSM, including 6 ketones, 1 aldehyde, 2 alcohols, 3 naphthenes , and 2 olefins, were found by using solid-phase microextraction coupled to gas chromatography-mass spectrometry. The possible degradation pathways of GSM and 2-MIB in UV/chlorine thus were proposed.
研究领域:
环境科学
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饮用水处理
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产品关联
DOI
PubMed
高影响因子
WATER RESEARCH
·
2019
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IF 7.913
Yang Wu,Yu Wang,Tao Pan,Xin Yang
The degradation of tetrabromobisphenol A (TBBPA), one of the most widely used brominated flame retardant , was evaluated during peroxymonosulfate (PMS) oxidation. TBBPA degradation was pH-dependent, with peak degradation rate constants occurring at pH 8.0–9.0, which was distinct from some other phenolic compounds . Singlet oxygen and radicals were found to play negligible roles in TBBPA degradation. TBBPA oxidation by PMS mainly proceeded via a direct oxidation pathway and the in-situ formed HOBr was found to greatly accelerate its degradation rates. The values of species-specific second-order rate constants for the reactions of PMS with the TBBPA k HSO5 − +TBBPA , k HSO5 − +TBBPA− and k HSO 5− +TBBPA2− were determined to be (1.11 ± 0.84) × 10 −2 , (8.05 ± 2.31) × 10 −2 , and (1.34 ± 0.25) × 10 −1 M −1 s −1 , respectively, while the reaction rate constants for HOBr/OBr − with TBBPA k HOBr+TBBPA , k HOBr+TBBPA− , k HOBr+TBBPA2− and k OBr−+TBBPA2− were determined to be (9.38 ± 2.10) × 10 3 , (1.59 ± 0.56) × 10 5 , (8.22 ± 0.41) × 10 6 , and (1.81 ± 0.12) × 10 6 M −1 s −1 , respectively. The bromine mass balance analysis showed that bromide ion and HOBr/OBr − occupied 19.5% of total Br and brominated organic compounds accounted for the remaining percentages at pH 7.0. No formation of bromate was observed. Based on the identified products, a reaction pathway was proposed, which included oxidation, β-scission, hydroxylation, and dimerization reaction pathways. The results indicate that unactivated PMS is useful for the remediation of TBBPA contaminated water .
研究领域:
环境科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
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2016
·Vol. 6
·期 81
·77499-77506
·
IF 3.289
Kai Zhang,Shubin Wu,He Yang,Huimin Yin,Gang Li
As promising and environmentally friendly catalysts, tungsten-containing heteropoly acids combined with supported noble metals were used for one-pot hydrothermal conversion of cellulose into polyols in the presence of pressurized hydrogen. The microcrystalline cellulose was completely converted over a mixed catalyst consisting of a low concentration of phosphotungstic acid (PTA) (0.03 wt%) and Ru/activated carbon (Ru/AC) via an one-pot hydrothermal reaction, with an ethylene glycol (EG) yield of up to 53.1% under optimal conditions. The catalytic activity of the mixed catalyst gradually decreased with increasing reaction runs, which could be mainly ascribed to the aggregation of Ru/AC particles, and to the coverage of the active sites of Ru due to the deposition of organic materials. Cellobiose was used as a model feedstock for a comparative study on the reaction pathways of the conversion of cellulose, and the results revealed that catalytic conversion of cellobiose consisted of at least three important parallel reactions under the present hydrothermal conditions, which were also most likely involved during the catalytic conversion of cellulose for EG production. Effective control of these reactions would be helpful to further maximize the EG yield during the catalytic conversion of cellulose.
研究领域:
化学工程
·
可再生资源转化
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产品关联
DOI
高影响因子
ACS Applied Energy Materials
·
2022
·
IF 6.959
Sisi Wu,Jing Yang,Ning Qin,Yingzhi Li,Haiou Wang,Yong-Wei Zhang,Qing Wang,Zhouguang Lu
LiO2 is a critical intermediate of oxygen reduction reaction in nonaqueous Li–O2 batteries that largely determines the discharge capacity and cycling stability. Currently, functional redox mediators that can promote the solution reaction route by enhancing the solvation of LiO2 have attracted tremendous interest to increase the attainable capacity. Conversely, redox mediators that quench LiO2 and facilitate the surface reaction route receive little attention. Here, we provide an in-depth exploration of the catalytic pathway and effect of a superoxide quencher that modulates the surface growth of Li2O2. Surprisingly, the predomination of the surface reaction route by ethyl viologen helps deliver a capacity as much as that promoted by the solution reaction route. The findings of this work provide a new direction of screening and evaluating functioning redox mediators for Li–O2 batteries.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
DOI
高影响因子
TALANTA
·
2018
·
IF 4.244
Feifei Meng,Zhenyu Lu,Runkun Zhang,Gongke Li
In this paper, a gaseous sensor was described for detection of iso -butanol on the basis of its strong cataluminescence (CTL) emission on nano-MgO surface. The sensor showed high sensitivity and specificity to iso -butanol with response time less than 1 s and recovery time less than 18 s. A good linearly relationship between CTL intensity and the concentration of iso -butanol was observed in the range of 7.6–3350 mg/m 3 ( r = 0.9992), the limit of detection was 2.5 mg/m 3 . The proposed CTL sensor exhibits good specificity to iso -butanol against other compounds including common alcohols. The possible reaction paths of iso -butanol on the MgO surface were investigated in detail. Results shows that the hydrogen atom abstraction of iso -butanol to form β -R iso following consumption via Waddington mechanism possible is a major reaction channel for CTL emission. The sensor was applied to analyze iso -butanol in spiked samples, satisfactory recoveries were obtained in the range of 96.6–112.8% and the RSDs were 5.0–10.1%, indicating that the proposed sensor is a promising candidate for rapid analysis of iso -butanol.
研究领域:
化学传感器
·
分析化学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Decun Luo,Ziyu Tang,Xiyang Yu,Tao Zhang,Chun-Ran Chang,Zhun Hu
The effect of ZrO 2 crystalline phases on Pd/ZrO 2 for catalytic combustion of toluene was investigated. It was found that Pd/t-ZrO 2 showed superior activity when the toluene concentration was lower than 2000 ppm, while Pd/m-ZrO 2 performed better with toluene concentration higher than 3000 ppm. Kinetic studies showed that the reaction order of toluene on Pd/t-ZrO 2 and Pd/m-ZrO 2 is 0 and 2, respectively. The catalytic activity was controlled by combined effect of PdO activity and quantity, which was correlated with the interaction between palladium and zirconia. The t-ZrO 2 increased PdO species activity, while m-ZrO 2 could enhance the amount of PdO. DFT results showed that the p-band center of the O of PdO on t-ZrO 2 was higher, suggesting that PdO was more active. In situ -DRIFTS revealed that the reaction pathway of catalytic oxidation of toluene on Pd/ZrO 2 was as follows: toluene was oxidized stepwise to benzyl alcohol, benzaldehyde, benzoic acid , CO 2 and H 2 O.
研究领域:
催化化学
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环境科学
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材料科学
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
·
2016
·
IF 3.698
Yingjie Li,Qingnan Liu,Wenfeng Li,Yingzhou Lu,Hong Meng,Chunxi Li
Mechanochemical destruction (MCD) is a good alternative to traditional incineration for the destruction of persistent organic pollutants (POPs), like hexachlorobenzene (HCB), and the key is to find an efficient co-milling reagent. Toward this aim, HCB was milled with various reagents in a planetary ball mill at room temperature, and CaC 2 was found to be the best one. HCB can be destroyed completely within 20 min at a mass ratio of CaC 2 /HCB = 0.9 and a rotation speed of 300 rpm. The ground samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy . The results show that the destruction products are nonhazardous CaCl 2 and carbon material with both crystalline and amorphous structures. On these bases, possible reaction pathways were proposed. Considering its excellent efficiency and safety, CaC 2 may be the most feasible co-milling regent for MCD treatment of HCB. Further, the results are instructive for the destruction of other POPs.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）