QUIMICA NOVA
·
2024
·
IF 0.5
Yu Yang,Shen Guoliang,Xu Tie jun,Wen Ruiyang,Wang Yong jie,Huo Yue,Xu Shi jie
Silicon catalysts have very low catalytic activity in polyester (PET). However, titanium catalysts have high catalytic activity in polyester. The simultaneous use of titanium and silicon catalysts is effective in reducing the activity of a single titanium catalytic base agent. In addition, the glycol salts of titanium and silicon (Ti-EG and Si-EG) prepared in the present invention for use in the polyester catalytic process can avoid the introduction of other groups of impurities during the polyester catalytic process, which would lead to premature capping of the polyester in the process of polycondensation and chain building and make it difficult to increase the molecular weight, and thus affect the quality of the polyester. It has been verified that the ratio of Ti:Si is 1:1 (mol), and total amount added to the catalyst is 0.15% of the raw material amount, and the polycondensation temperature was 260-280 °C for 60 min. Compared with the single Ti-EG catalyst, the b* value of the synthesized PET was significantly reduced, and the molecular weight and other indexes did not change too much. In addition, at the end of catalysis, the catalyst was uniformly dispersed in the reaction system, which could be used as a matting agent for PET.
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
FOOD HYDROCOLLOIDS
·
2014
·
IF 4.28
Xiuting Hu,Hongyan Li,Benxi Wei,Xueming Xu,Zhengyu Jin,Yaoqi Tian
The aim of this study was to examine 1-buatnol–hydrochloric acid (1-butanol–HCl) hydrolysis process of starch . Normal rice starch was hydrolyzed by 0.36% HCl in anhydrous 1-butanol at 40 °C from 4 h to 7 days. The changes in starch granule, crystalline, and molecular weight during the 1-butanol–HCl hydrolysis were determined using SEM, particle size analyzer, XRD, HPSEC–MALLS–RI, and iodine staining. SEM and particle size analyzer analysis showed that the granule morphology significantly changed and the granule size decreased from 5.47 μm to 5.07 μm after the hydrolysis by 1-butanol–HCl for 7 days. XRD results indicated that amorphous areas of normal rice starch were firstly hydrolyzed followed by the ordered areas during 1-butanol–HCl hydrolysis. The peak (2 θ ) of V-type crystallinity was detected at around 20° in the XRD curves of 1-butanol–HCl-hydrolyzed starches. This peak confirmed the formation of amylose–1-butanol complex. HPSEC–MALLS–RI and iodine staining analysis demonstrated that the weight-average molecular weight of normal rice starch sharply decreased from 2.4 × 10 7 Da to 4.9 × 10 5 Da after 1-butanol–HCl hydrolysis for 4 h, then gradually decreased, and finally stabilized at about 2.6 × 10 4 Da after hydrolysis for 4 days. These results suggest that the attack of 1-butanol–HCl on normal rice starch preferentially occurred in the amylopectin molecules of amorphous areas.
研究领域:
食品科学
·
生物化学
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产品关联
DOI
高影响因子
RUSSIAN CHEMICAL BULLETIN
·
2025
·Vol. 74
·期 3
·807-817
·
IF 0
Balakina A. A.,Amozova V. I.,Stupina T. S.,Mumyatova V. A.,Podgurskaya A. D.,Gadomsky S. Ya.
A new method for the synthesis of pyridoxine salts with dicarboxylic acids was proposed. The specific features of the synthesis include the preliminary generation of free pyridoxine from the hydrochloride form by treatment with a solution of triethylamine in chloroform and conduction of the reaction of pyridoxine with dicarboxylic acid in a specially selected solvent mixture. The combination of pyridoxine as a known antioxidant and fumarate as an activator of the transcription factor Nrf2 in one molecule gave rise to a unique structure, bis[3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridinium] fumarate (DPNF). In vitro experiments showed the ability of this compound to bind superoxide, suppress lipid peroxidation processes, and behave as a mitochondrial cytoprotective agent and Nrf2 activator. The results of the study can be used to develop a new type of drugs based on activators of the transcription factor Nrf2 to protect cells and tissues from oxidative damage.
研究领域:
药物化学
·
生物化学
·
分子生物学
✓ 已验证
DOI
Chemical Engineering and Processing-Process Intensification
·
2024
·
IF 3.8
Zifei Yan,Grace Dai Zhen Lee,Jian Deng,Guangsheng Luo
The synthesis of terminal epoxides, which are vital components in pharmaceuticals and resins, often involves dehydrochlorination of β-chlorohydrins. Although intrinsic kinetics indicate that the dehydrochlorination reaction in the presence of sodium hydroxide could be very rapid, the practical implementation could always be hindered by long reaction time and low conversion rate. Extended contact between the product and the alkaline solution can lead to hydrolysis of the epoxy group, thus necessitating the process intensification to realize higher production efficiency and selectivity. Here, by characterizing thermodynamic equilibrium data and in-situ recording of the reaction that proceeded in a constant interphase reactor, the heterogeneous dehydrochlorination is demonstrated to occur primarily in the organic phase, and the overall reaction rate depends on the equilibrium concentration of sodium alkoxides. This finding, which is fundamentally different from the traditional view that chlorohydrin is first dissolved in the aqueous phase and then reacts with NaOH, leads us to use inert alcohols to assist in the extraction of NaOH. Based on this method, the reaction time can be reduced over 80 % both in batch and continuous reactors. Besides, the method is demonstrated to be effective in the dehydrochlorination of five different long-chain β-chlorohydrins.
研究领域:
化学工程
·
有机合成
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS CHEMISTRY
·
2012
·Vol. 22
·期 43
·23169-23174
·
IF 5.968
Xianguang Ding,Yu Zou,Jiang Jiang
The synthesis of hybrid nanostructures has been of great interest to many material scientists, yet simple and facile routes to prepare these structures remain a difficult task with many reaction variables to tune. Herein, we report the synthesis of Au–Cu2S heterodimers from AuCu alloy nanoparticles by simply adding 1-dodecanethiol. Detailed characterization of this structural transformation process revealed that the crucial step of this synthetic approach was the alloy oxidization and subsequent formation of intermediate copper thiolate. Roles of surfactants and sulfur source have also been investigated. These observations provide critical insight into the understanding of the pathways of structure transitions from AuCu alloy to Au–Cu2S heterodimer nanoparticles, and will open up new ways of synthesizing heterodimer nanoparticles from metallic alloys.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
HETEROATOM CHEMISTRY
·
2015
·Vol. 27
·期 1
·63-71
·
IF 1.076
Wang Dai,Qiangqiang Liu,Xiaohui You,Zhongfei Zhou,Yanchun Guo,Yufen Zhao,Shuxia Cao
The Atherton–Todd-type reaction of hydrospirophosphoranes (HSPs) and sodium alcoholates was investigated. Direct alkoxylation of HSPs was accomplished with sodium alcoholates in acetonitrile under nitrogen atmosphere. The stereochemistry mechanism of the alkoxidation of HSPs was proposed by the 31 P NMR tracing experiment. The reaction proceeded via the chlorinated spirophosphorane intermediate with stereoretention of the configuration at phosphorus, followed by the rear and front attack of alkoxide anions to produce alkoxy spirophosphoranes. The reaction mechanism well explained the results of the reaction of HSPs with sodium alcoholates.
研究领域:
有机化学
·
合成化学
✓ 已验证
产品关联
DOI
高影响因子
ChemSusChem
·
2022
·Vol. 15
·期 11
·e202200474
·
IF 9.14
Shuai Li,Shenghai Yang,Kangkang Li,Yanqing Lai,Chaoyong Deng,Changhong Wang
Graphical A green system for hafnium alkoxide synthesis was proposed. Simultaneous heterogeneous Hf dissolution and ethanol dehydrogenation followed by spontaneous solution-based binding of alkoxy with Hf 4+ ions gave Hf(OEt) 4 . After the optimum conditions – electrolyte, temperature, current densities, etc. – had been determined, a proof-of-concept experiment achieved waste-free production of Hf(OEt) 4 with high purity and yield. Besides the system‘s green credentials, it showed a high net profit of 30 477 USD per kg Hf(OEt) 4 and could be extended to the synthesis of other hafnium alkoxides. The conventional thermal method of preparing hafnium alkoxides [Hf(OR) 4 , R=alkyl] – excellent precursors for gate-dielectric HfO 2 on semiconductors – is severely hindered by its unsatisfactory environmental and economic burdens. Herein, we propose a promising electrodissolution-coupled Hf(OR) 4 synthesis (EHS) system for green and efficient electrosynthesis of Hf(OR) 4 . The operational principle of the electrically driven system consists of two simultaneous heterogeneous reactions of Hf dissolution and alcohol dehydrogenation, plus a spontaneous solution-based combination reaction. In applying ethanol as solvent and Hf metal as electrodissolution medium, we achieved waste-free production of high-purity hafnium ethoxide [Hf(OEt) 4 ] with an equivalent “a concomitant” reduction in CO 2 emission of 187.33 g CO 2 per kg Hf(OEt) 4 and a high net profit of 30 477 USD per kg Hf(OEt) 4 . This system is very competitive with the thermal process, which unavoidably releases substantial waste and CO 2 for a net profit of 27 700 USD per kg Hf(OEt) 4 . We anticipate that the environmental and economic benefits of the EHS process could pave the way for its practical application.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2023
·
IF 3.6
Wen Li,Hexiang Wang,Yuan Zhang,Limin Zhao,Pengfeng Guo,Hua Cao,Xiang Liu
Pyridinium 1,4-zwitterionic thiolates were regarded as powerful and versatile building blocks to prepare nitrogen- and sulfur-containing heterocycles. Herein, we reported a copper-catalyzed formal [4 + 1] annulation of pyridinium 1,4-zwitterionic thiolates and diazo compounds without any additives to access a library of trifunctionalized indolizines in good yields. Besides, isoquinolinium 1,4-zwitterionic thiolates and imidazolium 1,4-zwitterionic thiolates were also applied to this formal [4 + 1] annulation reaction. Of particular note is that various functional groups such as −CO2R, −CO2NR2, −CF3, −CN, and −(O)P(OR)2 could be easily introduced into cycloaddition products indolizines by this strategy.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
PubMed
高影响因子
TETRAHEDRON
·
2012
·
IF 3.025
Jian-An Jiang,Wei-Bin Huang,Jiao-Jiao Zhai,Hong-Wei Liu,Qi Cai,Liu-Xin Xu,Wei Wang,Ya-Fei Ji
A concise ‘one-pot’ synthesis of a variety of 4-substituted 1,5-diaryl-1 H -pyrazole-3-carboxylates has been developed in moderate to good yields with excellent regioselectivity . Less cost lithium tert -butoxide has been identified as a base for sterically hindered Claisen condensation to efficiently generate the labile 3-substituted 4-aryl-2,4-diketoesters. Furthermore, extensive studies lead to a ‘one-pot’ process by combination of the Claisen condensation and the Knorr reaction for the synthesis of highly valuable 4-substituted 1,5-diaryl-1 H -pyrazole-3-carboxylates.
研究领域:
有机化学
·
药物化学
✓ 已验证
DOI
高影响因子
FOOD CHEMISTRY
·
2025
·
IF 9.8
Dingfeng Wang,Liwei Gao,Xinru Liu,Linfan Wang,Ting Zhang,Guoqiang Guo,Hongxing He,Da Chen
Trace detection of nitrite in food has gained increasing attention due to its connection with biological and environmental processes. Herein, a dual-mode fluorometric/colorimetric sensor is established for nitrite detection by combining the oxidase-like activity of iron alkoxide (IA) with the bimodal excitation properties of nitrogen-doped carbon dots (N-CDs). IA oxidizes the colorless 3,3′,5,5′-tetramethylbenzidine into blue-colored 3,3′,5,5′-tetramethylbenzidine oxide. Subsequently, nitrite further triggers a diazotization reaction, resulting in a color change from blue to green. Simultaneously, the fluorescence intensity of N-CDs at 470 nm decreases significantly, while the signal at 371 nm remains nearly unchanged, owing to the localized inner filter effect. Satisfactory results are attained with low limits of detection of 49 nM in the fluorometric mode and 73 nM in the colorimetric mode. Furthermore, an intelligent lateral flow assay platform is established for the visual detection of nitrite. Therefore, this work provides innovative guidance for nitrite detection in food safety.
研究领域:
食品安全
·
分析化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
STARCH-STARKE
·
2018
·
IF 2.173
Xiuting Hu,Yu Wang,Chengmei Liu,Zhengyu Jin,Yaoqi Tian
The 1-butanol-hydrochloric acid (1-butanol-HCl) degradation mechanism of high-amylose maize starch, represented by amylomaize V, is investigated using different methods. More pores are formed in the amylomaize V granules during 1-butanol-HCl hydrolysis and these pores become larger and change into cracks. Correspondingly, the average granule size slightly decreases from 13.49 to 10.87 µm after 1-butanol-HCl hydrolysis for 7 d. The crystalline areas of amylomaize V are hydrolyzed by 1-butanol-HCl and the amylose-1-butanol complex might form. In addition, the weight-average molecular weight of amylomaize V dramatically decreases from 1.25 × 10 7 to 3.57 × 10 5 Da after hydrolysis for 4 h, then slowly decreases, and stabilizes at about 2.00 × 10 4 Da after hydrolysis for 4 d, which is in accordance with the result of iodine staining analysis. High-performance anion-exchange chromatography analysis indicates that 1-butanol-HCl can hydrolyze the starch like hydrolysis patterns of both the endo-enzyme and the exo-enzyme. These results suggests that HCl in 1-butanol quickly diffuses into the whole amylomazie V granule and simultaneously attacks the crystalline and disorder areas, while the compact periphery of amylomaize V keeps the granules from disintegrating.
研究领域:
食品科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
ChemNanoMat
·
2020
·Vol. 7
·期 3
·270-276
·
IF 3.384
Shengrui Zhang,Yang Yu,Shujue Xu,Jun Liu,Mo Liu,He Su,Yajiao Hao,Minjie Li,Sean Xiao-An Zhang
Graphical Au(I)-thiolate nanosheets have been studied as new and efficient water-dispersible UV absorbents. UV screening is very important for the prevention of skin cancer and the elongation of the lifetime of organic/polymeric stuff. To overcome the main problems of poor hydrophilicity and easy leakage of organic UV absorbents, water-dispersible Au(I)-thiolate nanosheets have been studied as a new type of UV absorbents. The results show that Au(I)-thiolate nanosheets have i) very high molar absorption coefficients (>15000 mol/L . cm), ii) comparable or superior photostability to typical organic UV absorbents, and iii) high transparency and nearly no leakage in polymer matrix. So far, no other UV absorbents have been reported to have all the above good performances simultaneously. The transparent and colorless Au(I)-thiolate/polymer thin films can effectively block UV light, and such a material will surely extend the types and the application scenarios of UV absorbents.
研究领域:
材料科学
·
化学
·
医学
✓ 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）