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81.
A series of KF/Al2O3 catalyzed Michael-addition reactions between malononitrile and α,β-unsaturated cycloketones in DMF solution were studied. At room temperature, 2-cyano-3-aryl-3-(1,2,3,4-tetrahydronaphthalen-1-one-2-yl) propionitrile derivatives were synthesized by the reaction between 2-arylmethylidene-1,2,3,4-tetra-hydronaphthalen-1-one and malononitrile. However, if the temperature was increased to 80℃, 2-amino-3-cyano-4-aryl-4H-benzo[h]chromene derivatives were obtained in high yields. When the α,β-unsaturated ketones were replaced by 2,6-biarylmethylidenecyclohexanone or 2,5-biarylmethylidenecyclopentanone, another series of 2-amino-3-cyano-4H-pyran derivatives was isolated successfully. The structures of the products were confirmed by X-ray diffraction analysis. 相似文献
82.
系列单取代烷氧基-2-羟丙基-β-环糊精的合成与表征 总被引:1,自引:0,他引:1
以环氧氯丙烷和脂肪醇为原料, 通过相转移催化法合成了乙基、正丙基、正丁基和正戊基缩水甘油醚(1~4), 并利用所合成的缩水甘油醚和β-环糊精为原料, 分别在弱碱水溶液(1.5%)和强碱水溶液(30%)中制备并用硅胶柱分离出单2位取代的乙氧基、丙氧基、丁氧基和戊氧基-2-羟丙基-β-环糊精(1a~4a)和单6位取代的丙氧基、丁氧基和戊氧基-2-羟丙基-β-环糊精(2b~4b), 利用薄层色谱、红外光谱、差热扫描量热分析、质谱和核磁共振等手段对所合成的产品进行了表征. 相似文献
83.
The use of grape tissue as a source of catalase for the determination of hydrogen peroxide is reported. A slice of grape tissue attached to the membrane of a Clark-type oxgen sensor was used to monitor the oxidation of hydrogen peroxide by catalase. At the steady state, the sensor responds linearly to hydrogen peroxide in the concentration range 1 × 10?5–5 × 10?4 M. The response time (T90) was of the order of 1 min for this sensor. No interference was observed from ethanol, amino acids, glucose and lactic acid. The long-term stability of the grape tissue sensor was much better than previously reported immobilized enzyme and liver tissue-based hydrogen peroxide sensors. 相似文献
84.
The B3LYP and MP2 methods with 6-31G* basis set were used to predict the geometries of N, N-dimethylformamide (DMF) dimer and DMF–aromatic hydrocarbons interaction systems. A total of 10 conformers were obtained with
no imaginary frequencies, respectively. The interaction energies of these binary mixtures have been obtained. The analyses
of chelpg charge distribution and the atoms in molecules theory (AIM) were used to analyze the nature of the interaction.
The results show the presence of hydrogen bonds between DMF and aromatic hydrocarbons. The interaction between DMF and benzonitrile
is the strongest with the interaction energy of −21.58 kJ mol−1 (BSSE corrected), and the intensity order of interactions is DMF–benzonitrile: d2 > DMF–DMF: a2 > DMF–toluene: c1 > DMF–benzene:
b2. 相似文献
85.
In this study, the determination of 4-Bromoaniline (4-BA) in green algae Chlamydomonas reinhardtii (C. reinhardtii) was investigated by applying continuous-flow microextraction (CFME) combined with high-performance liquid chromatography
(HPLC). Continuous-flow microextraction was conducted in a homemade glass chamber, i.e. the sample solution flowed through
a constant volume drop of solvent in the chamber at a constant flow rate. The effects of different factors on extraction efficiencies
were also investigated and these factors included the kind of extraction solvent, solvent drop volume, sample flow rate, extraction
time and addition amount of salt. Under the optimum extraction conditions (extraction solvent, carbon tetrachloride; solvent
drop volume, 3.5 μL; sample flow rate, 1.0 mL min−1; extraction time, 10 min; no addition of salt), the calibration plot was set up by plotting peak area against a series of
4-Bromoaniline concentrations (0.01–10 μg mL−1) in aqueous solution. The correlation coefficient (r) was 0.9990. The limit of detection (LOD) was 0.6 ng mL−1. The precision of this method was obtained by successive five time analyses of 100-ng mL−1 standard solution of 4-Bromoaniline, and the relative standard deviation (RSD) was 3.5%. The concentration factor was calculated
by the ratio of peak area of the analyte obtained after and before extraction and found to be 10.6. 4-Bromoaniline residues
in Chlamydomonas. reinhardtii cells and tap water samples were satisfactorily analyzed according to the method described above. 相似文献
86.
87.
IntroductionItiswellknownthatyttriumcanbeusedinmanyfields ,suchasmetallurgy ,ceramics ,lasersandelectron ics ,especiallyinfluorescentmaterialswhoseneedforhighpurityyttriumoxideisincreasing .InChina ,there sourceofyttriumisrich ,andthehighpureyttriumisbe ingo… 相似文献
88.
89.
Guo‐Fu Chen Chang‐Heng Tan Zhu‐Lian Li Shan‐Hao Jiang Da‐Yuan Zhu 《Helvetica chimica acta》2003,86(3):787-792
Pseudolarolides O ( 1 ) and P ( 2 ), two novel triterpenoids with a cycloartane‐type framework, were isolated from the seeds of Pseudolarix kaempferi Gord. (Pinaceae). Their structures were elucidated as (16R,23S,25R)‐16,23‐epoxy‐3,4 : 9,10‐disecocycloartan‐1(10),9(11)‐diene‐3(4),26(23)‐diolide ( 1 ), and (9S,16R,23S,25R)‐1,9 : 16,23‐diepoxy‐8,9 : 9,10‐disecocycloartan‐1(29),5(6),10(19)‐triene‐3(4),26(23)‐diolide ( 2 ), respectively, on the basis of spectroscopic techniques and X‐ray‐diffraction studies. 相似文献
90.
1—酰基—4—氯环己烷与取代芳烃的区域与立体选择性反应 总被引:2,自引:0,他引:2
从环己烯合成了1-酰基-4-氯环己烷,发现在其在AlCl3催化与苯,氯苯,溴苯等优先生成反式1-芳基-4-酰基环己烷,与联苯反应时选择性较差。 相似文献