SYNTHESIS-STUTTGART
·
2025
·
IF 2.3
Lulu Qin,Tao Yu,Zhengwei Ding,Min Zhao,Pengfei Li
A highly efficient protocol for the synthesis of trifluoromethyl-substituted cyclopentanes, a structural motif ubiquitous in bioactive compounds and natural products, via boron-radical-catalyzed (3+2) cycloaddition of aroylcyclopropanes and trifluoromethyl-substituted alkenes was developed. Employing readily available precursors, this modular, atom-economical, metal-free, and operationally simple process was compatible with diverse functional groups, giving the products in generally good to high yields. Trifluoromethyl-substituted bicyclo[2.1.1]hexanes (BCHs) were analogously prepared.
研究领域:
有机化学
·
药物化学
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DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2023
·
IF 6
Hongyan Wang,Yurou Zhou,Jingpei Cao,Bofeng Zhang,Yajie Tian,Guozhu Liu
Adamantane derivatives, as promising high-density fuels, have been widely concerned in fields of volume-limited aerospace vehicles due to high density, heat of combustion and thermal oxidation stability. To reveal insights into their high-temperature decomposition behaviors, an experimental and theoretical investigation of adamantane (A) and 1-methyl adamantane (1-MA) pyrolysis was performed in a flow tube reactor at atmospheric to high pressure. Over twenty species were detected and identified, including C1-C5 light hydrocarbons, C5-C7 cyclic olefins as well as C6-C12 aromatics. The favorable decomposition channels of A and 1-MA are proposed and the effects of fuel structure characteristics and pressures on product formation behaviors are revealed. For the primary decomposition of A and 1-MA, the contributions of reaction types exhibit the obvious dependence on the pressures and temperatures, involving the unimolecular C-C dissociations by ring-opening, CH 3 -elimination as well as H-abstractions by H and CH 3 attacking. Considering methyl-substitution weakens dissociation energies of C-C and C-H bonds and leads more H-abstraction sites, 1-MA shows a higher pyrolysis reactivity than A. The effects of structure characteristics are also embodied in the formation of newly chain-branched unsaturated species and the concentrations of common small hydrocarbons and aromatics. Compared to A decomposition, the methyl substituent in 1-MA promotes the emergence of 1-butene, 2-methyl-1-butene, mesitylene, methylindane and methylnaphthalene, and increases the concentrations of methane, 2-methylpropene and xylene isomers, formed via β-scission, hydrogen transfer, isomerization and dehydrogenation routes of fuel radicals. Meanwhile, more methyl-substitutions accelerate the decomposition of alkyl-adamantanes and pyrolysis activity follows by a sequence of dimethyl-adamantane > methyl-adamantane > adamantane, boosting the production of methyl-specific species.
研究领域:
化学动力学
·
燃料化学
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产品关联
DOI
高影响因子
Polymers
·
2023
·Vol. 15
·期 13
·2853
·
IF 5
Yurong Zhang,Haidan Lin,Kai Dong,Shasha Tang,Chengji Zhao
A series of epoxy resins containing various trifluoromethyl groups were synthesized and thermally cured with diaminodiphenylmethane (DDM) and aminophenyl sulfone (DDS). All epoxy resins exhibited excellent thermal stability with the glass transition temperatures of above 128 °C and 5% weight loss temperatures of above 300 °C. DDS-cured epoxy resins possessed higher thermal stability than that of DDM-cured epoxy resins, while DDM-cured epoxy resins showed better mechanical, dielectric, and hydrophobic properties. Additionally, DDM-cured epoxy resins with different locations and numbers of trifluoromethyl groups showed flexural strength in the range of 95.55~152.36 MPa, flexural modulus in the range of 1.71~2.65 GPa, dielectric constant in the range of 2.55~3.05, and water absorption in the range of 0.49~0.95%. These results indicate that the incorporation of trifluoromethyl pendant groups into epoxy resins can be a valid strategy to improve the dielectric and hydrophobic performance.Keywords:trifluoromethyl substitution;low dielectric constant;hydrophobicity;thermal stability
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
POLYMER
·
2022
·
IF 4.432
Mengdi Chen,Jinzhao Li,Long Chen,Yue Qin,Ming Xiao,Yuechuan Wang
Fluorination reduces dielectric constant and dielectric loss of epoxy resins , expanding their applications in high-speed communication. The methyl group (-CH 3 ) is a non-polar and space-occupying group, and it can reduce dielectric constant ( D k ) in some situations. However, it is not well understood how the methyl groups affect dielectric properties , as well as thermal and mechanical properties of fluorinated epoxy resin. To address this question, we specifically select benzene and m-xylene as the reaction monomer for comparison. We synthesize two fluorinated epoxides , diglycidyl ether of 1,3-bis(1,1,1,3,3,3-hexafluoroisopropyl)-benzene (DGE-bHFIP-B) and diglycidyl ether of 4,6-bis(1,1,1,3,3,3-hexafluoroisopropyl)-m-xylene (DGE-bHFIP-MX). We then thermally cure these two epoxides catalyzed with boron trifluoride ethylamine (BF 3 ·MEA) to obtain EP-bHFIP-B and EP-bHFIP-MX. EP-bHFIP-MX with –CH 3 has D k of 2.49–2.51, slightly lower than EP-bHFIP-B with D k of 2.51–2.54 at a high frequency range of 8.2–12.4 GHz. Their D k is much lower than a commercial bisphenol A type epoxy resin (EP-51) with D k of 2.80–2.83. Additionally, EP-bHFIP-MX shrinks less than EP-bHFIP-B after curing, and exhibits higher glass transition temperature with T g − D M A of 181 °C, higher tensile strength of 39.76 ± 5.51 MPa, compared to 129 °C and 34.73 ± 5.10 MPa for EP-bHFIP-B. EP-bHFIP-B and EP-bHFIP-MX both have very low water absorption of 0.134% w/w and 0.147% w/w after being immersed in water for 24 h at 25 °C. Therefore, incorporating –CH 3 groups into phenylene rings of fluorinated epoxies, we can enhance thermal resistance , increase mechanical strength , and reduce shrinkage without compromising dielectric performance.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2017
·
IF 2.536
Xuefeng Wang,Hua Wang,Qin Jiang,Yong-Ill Lee,Shengyu Feng,Hong-Guo Liu
In this study, thiophene was linked to polybenzene to generate novel fluorescent probes , namely 3,4-diphenyl-2,5-di(2-thienyl)phenyl-trimethylsilane (DPTB-TMS) with a − SiMe 3 substituent and 3,4-diphenyl-2,5-di(2-thienyl)phenyl (DPTB) without the − SiMe 3 substituent, respectively. Both of the two compounds exhibit aggregation-enhanced emission (AEE) properties in tetrahydrofuran/water mixtures due to restricted intramolecular rotation of the peripheral groups, which make the two compounds good candidates for the detection of Fe 3 + ions in aqueous-based solutions. The fluorescence intensity of the two compounds decreases immediately and obviously upon addition of a trace amount of Fe 3 + , and decreases continuously as the amount of Fe 3 + increases. The fluorescence was quenched to 92% of its initial intensity when the amount of Fe 3 + ions reached 6 μmol for DPTB-TMS and to 80% for DPTB in the systems, indicating that the compound with the − SiMe 3 group is a more effective probe. The detection limit was found to be 1.17 μM (65 ppb). The detection mechanism is proposed to be static quenching. DPTB-TMS is highly efficient for the detection of ferric ions even in the presence of other metal ions . In addition, the method is also successfully applied to the detection of ferric ions in water, blood serum, or solid films. This indicates that these polybenzene compounds can be applied as low-cost, high selectivity, and high efficiency Fe 3 + probes in water or in clinical applications.
研究领域:
化学
·
分析化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
HIGH PERFORMANCE POLYMERS
·
2020
·
IF 1.568
Lei Zhang,Jiale Mao,Shuang Wang,Yiting Zheng
A series of main-chain benzoxazine oligomers with different methyl substitutions are successfully synthesized. Chemical structures are analyzed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Effects of methyl substitutions on chemical shifts of protons in oxazine ring and thermal properties, including glass transition temperature, thermal stability, and char yield, are discussed. The influences of methyl substitutions on different positions are demonstrated: (i) substitution on phenols induces obvious increase in curing temperature while substitution on amine does not show apparent impact; (ii) substitution at different positions results in T g variation, following the sequence of none-substitution > substitution at end-capping > substitution on diamines in main-chain > substitution on bisphenols in main-chain; and (iii) substitution at end-capping would cause apparent deterioration in thermal stability while substitution on diamines in main-chain would benefit thermal stability and char yield. Experimental results and related explanations are provided in detail.
研究领域:
材料科学
·
有机化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Jiawei Xie,Yi Liu,Tinghao Jia,Lun Pan,Yunming Fang,Chengxiang Shi,Genkuo Nie,Xiangwen Zhang,Ji-Jun Zou
Alkyl-adamantane fuels have drawn tremendous attention for aerospace vehicles due to their high density and high oxidation stability. Here, we reported a regioselective route to synthesize methyl-substituted adamantanes including 1,3,5-trimethyl-adamantane and 1,3,5,7-tetramethyl-adamantane with single configuration via alkylation of 1,3-dimethyl-adamantane, with yields of ∼60 and ∼80%, respectively. The reaction kinetics of alkylation has been investigated, and the reaction rate constants and apparent activation energies were calculated based on the experimental kinetic data. The oxidation stability of methyl-substituted adamantane family were first evaluated via pressure differential scanning calorimetry and rapid small-scale oxidation test, and the results indicate that the oxidation stability is correlated to the carbon type available on the molecule in the order of 1,3,5,7-tetramethyl-adamantane > 1,3,5-trimethyl-adamantane > 1,3-dimethyl-adamantane > 1-methyl-adamantane. Notably, 1,3,5,7-tetramethyl-adamantane with four quaternary carbons and no tertiary carbon presents supreme oxidation stability than JP-10 and decalin. Finally, we used 1,3,5,7-tetramethyl-adamantane as an additive and achieved in improving the oxidation stability of JP-10. This work presents methyl-substituted adamantanes as good high-density and high-oxidation-stability fuel components and suggests that methyl groups substituted on tertiary carbon of adamantane has a beneficial effect on improving oxidation stability.
研究领域:
化学工程
·
航空航天燃料研究
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2019
·Vol. 34
·期 4
·545-554
·
IF 1.982
Yong Xu,Linshuang Li,Jianfei Che,Zhifeng Ye
A series of optically transparent and colorless semi-fluorinated poly(ether imide)s (PEIs) (III) were prepared from non-fluorinated 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride (HQDPA) with various trifluoromethyl-substituted diamines. The III series showed more colorless and higher optical transparency with a cutoff absorption wavelength (λ0) below 370 nm than the IV series based on the corresponding non-fluorinated analogues and V series derived from CF3-free pyromellitic dianhydride (PMDA). Compared with the fluorinated VI series based on fluorinated 4,4′-hexafluoroisopropylidenediphthalic anhydride (6FDA), the semi-fluorinated III series not only exhibited much better optical transparency, but also had better mechanical and thermal properties. The III series had a tensile strength of 79.8–109.5 MPa, modulus of elasticity of 3.0–7.7 GPa and elongation at break of 14.2–26.7%, together with glass-transition temperatures (Tg) ranging from 214.3 to 265.1 °C and temperatures of 5% weight loss (T5%) beyond 530 °C. Meanwhile, the novel semi-fluorinated PEI IIIb was optically transparent and colorless with a λ0 of 367 nm coupled with dielectric constants below 3.2 and contact angles against water over 112°. In particular, the optically transparent IIIa exhibited the best tensile strength of 109.5 MPa when compared with already reported counterparts.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2025
·
IF 3.4
Yaqi Qin,Xiaoyu Feng,Jinkang Ma,Fanghao Xuan,Kaiwen Hu,Lifeng Cao,Dongwei Zhai,Bing Teng
Two novel chalcone crystals, 5MFTF (C15H11F3O2, P1) and 5MFTN (C14H11NO4, P1), were successfully synthesized by introducing trifluoromethyl and nitro substituents, respectively. Growth of the crystals was carried out by a slow evaporation solution method. The structures of the crystals were successfully verified by the results of 1H NMR, FT-IR, and powder XRD tests. The crystal stacking arrangements of 5MFTF and 5MFTN were characterized via a single-crystal X-ray diffraction (XRD) technique. The second-harmonic generation (SHG) measurements revealed that 5MFTF exhibited an SHG intensity 7.5 times that of potassium dihydrogen phosphate (KDP), while 5MFTN showed a SHG intensity 5.2 times that of KDP. The hyperpolarizability and FMOs were also calculated. In order to reveal the microscopic charge transfer mechanism in crystalline materials (5MFTF and 5MFTN), hole–electron analysis and interfragment charge transfer were calculated. 5MFTN crystal exhibited higher thermal decomposition temperatures compared to the other chalcone crystals (Tm ≈ 207 °C). All of these results indicate that the 5MFTF and 5MFTN crystals are promising for optical applications.
研究领域:
材料科学
·
光学材料
·
晶体工程
·
非线性光学
·
有机合成
✓ 已验证
DOI
高影响因子
Materials Today Communications
·
2025
·
IF 4.5
Tianci Ma,Jinglei Xing,Lei Yang,Long Wang,Xingzhong Fang,Guofei Chen
As is known to all, it is an effective strategy to achieve transparent aromatic polyimides by introduction of fluorine-containing monomer. However, due to the prohibition of perfluoroalkyl and polyfluoroalkyl substances (PFAS), fluorine-free polyimides have attracted more and more attention. In order to investigate the structure-properties relationship of fluorine-free transparent polyimides, a new diamine monomer, 2′,3,3'',5′-tetramethyl-[1,1′:4′,1''-terphenyl]-4,4''-diamine (3TMTD) containing methyl group and terphenyl structure, was successfully synthesized, and a series of highly heat-resistant polyimides were synthesized by 3,3′,4,4′-diphenylsulfone tetracarboxylic acid anhydride (DSDA) with 2,2′-bis(methyl)-4,4′-benzidine (2,2′-DMBZ), 3,3′-bis(methyl)-4,4′-benzidine (3,3′-DMBZ), 3TMTD, 9,9-bis(4-aminophenyl)fluorene (FDA) and 9,9-bis(3-methyl-4-aminophenyl)fluorene (MFDA). And the polyimide containing fluorine element derived from DSDA and 2,2′-bis(trifluoromethyl)-4,4′-benzidine (TFDB) was also prepared for comparison. The effects of different methyl substitution positions and numbers, as well as fluorine-containing diamine and fluorine-free diamines, on the properties were well studied. The resulting polyimides exhibited high T g s of 373–426 °C, transmittances at 450 nm of 66–87 %, and tensile moduli of 2.8–4.0 GPa. Among them, PI-3 derived from DSDA and 3,3′-DMBZ showed the highest T g of 426 °C, while PI-4 derived from DSDA and 3TMTD dispalyed the best comprehensive performance with T g of 405 °C, transmittance of 80 % at 450 nm, tensile strength of 167.6 MPa and tensile modulus of 4.0 GPa.
研究领域:
高分子科学
·
材料工程
·
有机合成
·
光学材料
·
高性能聚合物
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Guangzhi Xu,Zhuoheng Tu,Xingbang Hu,Mian Li,Xiaomin Zhang,Youting Wu
Furfural (FF) is an important platform molecule originated from biomass, but it’s synthesis through the traditional acid-catalyzed dehydration reaction of xylose and hemicellulose remains problematic due to the poor activity and equipment corrosion. Therefore, a series of [HSO 4 ]-based protic Brønsted acidic ionic liquids (BAILs) are employed as green catalysts to achieve efficient and sustainable preparation of FF from xylose or hemicellulose in this work. Furfural yields of 75.4% or 80.4% were achieved under optimal operating conditions with [Hpy][HSO 4 ] as catalyst, hemicellulose or xylose as substrates, higher than those catalysed with most ionic liquids reported so far. The chemical structures of BAILs were confirmed by NMR and FT-IR spectroscopy, and the Hammett acidity ( H 0 ) were determined using UV–vis spectroscopy with 4-nitroaniline as probe. The acidity of BAILs were tuned through methyl substitution on the pyridinium ring, and its effect on the catalysis performance was investigated. In addition, the reaction constants and the corresponding activation energies of BAILs for dehydration of xylose to FF were calculated by kinetic equations. Overall, the highly efficient catalysis performance, good recyclability and low cost enables [Hpy][HSO 4 ] to be potentially applied for large-scale preparation of FF.
研究领域:
化学工程
·
催化
·
可再生能源
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Jing-Bo Wang,Xue-Ru Zhao,Xi-Le Hu,Yi Zang,Jia Li,Xiao-Peng He
The sensitive detection of glycosidases in live cells is crucial to understanding their functional roles in disease progression. Here, we develop a fluorogenic labeling probe for β-galactosidase (β-Gal) based on a bright green-emitting fluorescent dye, fluorescein. Galactose was introduced to a fluoromethyl-substituted fluorescein derivative through a benzyl spacer, resulting in a quenched fluorescence due to spirocyclization of the dye. After removal of the galactosyl residue by β-Gal, an ∼210-fold enhanced green fluorescence (emission maximum at 524 nm) was detected, and the presence of other glycosidases and hydrolases did not produce false-positive signals. The probe was successfully used for imaging of the endogenous β-Gal activity in cancer and senescent cells, and the imaging results agree with the β-Gal expression level of the cells, as determined by Western blotting and polymerase chain reaction. Importantly, we demonstrated that upon hydrolysis of galactose, the fluoromethyl-substituted fluorescein derivative is covalently attached to adjacent proteins, both in solution and in live cells. This study offers a small-molecule probe for the sensitive monitoring of endogenous glycosidase activity.
研究领域:
生物化学
·
分子生物学
·
细胞生物学
·
癌症研究
·
衰老研究
✓ 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）