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71.
探讨了HELP法在水中酚类色谱重叠峰的分辨与定性定量分析中的应用.实验结果表明,各组分浓度比为1:50的范围内分辨光谱与真实光谱十分吻合.在10-4~10-6g/mL的浓度范围内分辨色谱的定量结果线性关系良好.分辨下限3.0×10-7g/mL,相对标准偏差为5.0%. 相似文献
72.
Zhen Xiu He Yongyun Zhou Baiqiu Han Xin Xu Yun Li Hongyu Qin Ruifeng Fan Ronibala Devi Laishram Baomin Fan 《Tetrahedron》2018,74(17):2174-2181
An efficient asymmetric ring opening reaction of azabenzonorbornadienes with various phenols using Palladium/(R,R)-DIOP complex has been demonstrated, the reaction afforded the corresponding products in excellent yields (80–95%) with moderate enantioselectivities (50–64% ees). The syn-configuration of the product was confirmed by the single X-ray crystallography. 相似文献
73.
《Arabian Journal of Chemistry》2021,14(11):103424
Six novel lactamomethyl derivatives of 2,5-dimethylphenol and 2,3,5-trimethylphenol were prepared with moderate yields by the reaction of corresponding phenols with 1-(hydroxymethyl)lactams in the presence of an acid catalyst. In all cases, the substitution occurred at position 4 to the phenolic hydroxyl group. The structures of all synthesized compounds were confirmed by FT-IR, 1H and 13C NMR, 2D NMR and elemental analysis. The selectivity and possible pathways of the lactamomethylation reaction were studied by quantum-chemical methods. In silico calculations showed that the substitution at para-position to the hydroxyl group of the corresponding phenols was more preferable due to the higher stability of forming intermediates. 相似文献
74.
A method for the determination of the migration of 14 endocrine disruptors(bisphenol A,bisphenol E,bisphenol F,bisphenol S,bisphenol B,bisphenol Z,bisphenol AF,bisphenol AP,tetrabromobisphenol A, tetrachlorobisphenol A,octylphenol,4-n-octylphenol,4-nonylphenol and 4-n-nonylphenol)in food packaging materials by liquid chromatography-tandem mass spectrometry was developed. The samples were soaked in water,4% acetic acid solution,10% ethanol solution,50% ethanol solution,olive oil,simulated sweat and simulated saliva. The soakings were purified by solvent extraction or Oasis HLB solid phase extraction. After separation by a Waters Atlantis™ T3 column,the samples were determined by multiple reaction monitoring mode with electrospray negative ion source,and quantified by matrix external standard method. The linear correlation coefficients of 14 endocrine disruptors were 0.9901-0.9986,the recoveries were 82.3%-108.7% with the relative standard deviations of 0.8%-6.8%,the limits of detection were 0.1-0.5 μµg/L and the limits of quantification were 0.3-1.5 μµg/L. © 2023, Youke Publishing Co.,Ltd. All rights reserved. 相似文献
75.
Henry P. Caldora Dr. Zhenhua Zhang Dr. Michael J. Tilby Dr. Oliver Turner Prof. Daniele Leonori 《Angewandte Chemie (International ed. in English)》2023,62(25):e202301656
Phenols are integral aromatic molecules widely encountered in the structure of natural products and routinely utilised for the synthesis of high-value materials. Accessing highly substituted derivatives can often be difficult, especially when their functionalization pattern does not match the intrinsic reactivity leveraged by electrophilic aromatic substitution (SEAr) chemistry. Here, we provide an alternative and mechanistically distinct approach for phenol synthesis using saturated cyclohexanone precursors. This process operates at ambient temperature, under simple purple light irradiation, and features a dual catalytic manifold carrying four sequential H-atom transfer processes. 相似文献
76.
Guaiacol, pyrocatechol and resorcinol, were isolated and quantified as the major products from catalytic pyrolysis of lignin of various origin. The novel procedure utilises formic acid as the hydrogen source in combination with a palladium catalyst and Nafion® SAC-13 as a solid acid catalyst with water as reaction medium. The reaction is conducted at moderate pyrolysis temperature and short reaction time. Several palladium based catalysts and different types of lignin were investigated. The lignins and the model compounds demonstrated various chemical behaviour, under identical reaction conditions; various phenols were formed from the lignins, while the model compounds were hydrodeoxygenated, demethylated and demethoxylated. 相似文献
77.
Shaji Varghese Chokkalinkam Anand Dattatray Dhawale Ajayan ManoVeerappan V. Balasubramanian George Allen Gnana RajSamuthira Nagarajan Mohammad A. WahabAjayan Vinu 《Tetrahedron letters》2012,53(42):5656-5659
A novel mesoporous catalyst, CuAl-SBA-15, with a hexagonally ordered porous structure prepared via a soft-templating approach in a highly acidic medium is used for tandem C-C and C-O bond formation between phenols and allylic alcohols to afford a variety of dihydrobenzopyrans in good yields. The catalyst is also found to be highly active for the synthesis of vitamin E and can be recycled several times without significant loss of its activity. 相似文献
78.
Ignacio López José Luis BravoManuel Caraballo José Luis BarnetoGuadalupe Silvero 《Tetrahedron letters》2011,52(26):3339-3341
The ionic liquid 1-butyl-3-methylimidazolium acetate proves to be an excellent reaction medium for the acetylation of alcohols and phenols, providing better conditions than the acidic 1-butyl-3-methylimidazolium bisulfate. Reactions were carried at room temperature, with only a 10% excess of acylating agent and with no other solvent or catalyst added. 相似文献
79.
Raza Murad Ghalib Rokiah Hashim Othman Sulaiman Mohd Fahmi B. Awalludin Sayed Hasan Mehdi Fumio Kawamura 《Journal of Saudi Chemical Society》2011,15(3):229-237
The bark and wood of Sonneratia caseolaris (L.) Engl. have been analyzed for chemical profile by GC–TOFMS. Overall thirty-two compounds from bark and twenty-eight compounds from wood have been detected. Sixteen constituents have been found to be common in both the extracts. GC–TOFMS chemical profile may be a significant finger print chemotaxonomic marker as an identity of this plant. 相似文献
80.
《Analytical letters》2012,45(9):1659-1669
SUMMARY The development of amperometric biosensors based on polyphenol oxidase (PPO) as a novel tool for the determination of phenolic compounds is described. Biosensors have been obtained using different PPO-rich matrices: tissue slices from mushroom and potato, acetonic powder from mushroom; lyophilised enzyme from mushroom (tyrosinase-SIGMA). A large variety of immobilisation procedures have been used with pure enzyme and acetonic powder. Behaviour of all biosensors obtained has been investigated in terms of sensitivity. linearity range, response time and half life time. Preliminary experiments have been carried out, using a Flow Injection Analysis, with standard solutions of catechol and phenol in the range 1-10 mM, then biosensors have been also tested on a real sample (green water from crushers) with a direct method and a standard addition, one obtaining good reproducibility. 相似文献