共查询到20条相似文献,搜索用时 54 毫秒
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李支薇刘晓琴冯桂冰 《理化检验(化学分册)》2018,(1):35-38
提出了气相色谱-质谱法测定塑料和电子电气产品中N-乙烯基吡咯烷酮的含量的方法。样品1.000 0 g用四氢呋喃10 mL超声提取30 min,提取液经0.45μm聚四氟乙烯滤头过滤后,采用气相色谱-质谱法进行测定,以DB-624毛细管色谱柱进行程序升温,在全扫描模式下选择m/z 56,111,28,41为定性离子,在选择离子监测模式下以m/z 111为定量离子。N-乙烯基吡咯烷酮的质量浓度在0.05~10 mg·L^(-1)内与其峰面积呈线性关系,检出限(3S/N)为0.1 mg·kg^(-1)。按标准加入法进行回收试验,回收率在94.9%~114%之间,相对标准偏差(n=7)在0.040%~1.6%之间。 相似文献
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以γ射线引发顺丁烯二酸β-环糊精酯(CDM)和N-乙烯基吡咯烷酮(NVP)发生自由基链式反应,制备了顺丁烯二酸β-环糊精酯-N-乙烯基吡咯烷酮聚合物(CDM-NVP).优化后的CDM-NVP聚合物的合成条件为: CDM∶NVP为1∶0.7(w/w, CDM 3.6 g 和 NVP 2.52 g),辐照剂量4 kGy,DMF溶液用量为20 mL.在此条件下制备聚合物的产率为84%,重均分子量为20 kDa.结果表明,此聚合物可以同纳他霉素(NM)和多菌灵(MBC)形成稳定复合物.研究了复合物抑菌活性,测定了其表观稳定常数.利用紫外光谱、核磁图谱和相溶解度对药物复合物进行结构表征.303 K下,NM-CDM-NVP和 MBC-CDM-NVP复合物的表观稳定系数分别为12988.54和865.94 L/mol.抑菌实验结果表明,NM-CDM-NVP和 MBC-CDM-NVP复合物可以显著提高NM和MBC的溶解性和抑菌活性. 相似文献
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由丙烯酰胺、马来酸酐、N-乙烯基吡咯烷酮和烯丙基磺酸钠在过硫酸铵-亚硫酸氢钠氧化还原引发体系下合成了一种新型的AM/MA/NVP/SAS四元共聚物。确立了最佳反应条件:n(AM)/(MA)=6:2(mol)引发剂用量0.5 wt%,反应温度45℃,反应时间为5 h,pH为8;并通过红外光谱分析确认了AM/MA/NVP/SAS四元共聚物结构。当NaCl,CaCl2浓度分别在10000 mg/L,3000 mg/L时,AM/MA/NVP/SAS四元共聚物的表观粘度可保持在20 mPa.s左右,而粘度保留率约为30%。 相似文献
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An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
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An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction. 相似文献
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The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed. 相似文献
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Xi-Liu YunWen-Ying Bi Jian-Hui HuangYu Liu Daisy Zhang-NegrerieYun-Fei Du Kang Zhao 《Tetrahedron letters》2012,53(38):5076-5080
A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd2(dba)3-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring. 相似文献
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Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles. 相似文献
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An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C60 and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C60, followed by SET from the amine to the triplet excited state of C60. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C60 radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared. 相似文献
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Viktor A. Dmitriev Mariia M. Efremova Alexander S. Novikov Vladimir V. Zarubaev Alexander V. Slita Anastasia V. Galochkina Galina L. Starova Andrey V. Ivanov Alexander P. Molchanov 《Tetrahedron letters》2018,59(24):2327-2331
The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities. 相似文献
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A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields. 相似文献
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Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl3-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction. 相似文献
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Yin Shuhui Liu Hongping Zhang Jianyang Jiang Bo Wang Li Sha Guohe Lou Nanquan 《化学物理学报(中文版)》2003,16(1):3-8
The multi-photon dissociative photoionization dynamics of CF3I has been studied with femtosecond two-color pump-probe time of flight mass spectra at a pump pulse of 265 nm and a probe pulse of 398 nm. The life constants of CF3I+ and its fragment ions CF3+ and I+ are obtained as (96±7), (198±130) and (167±6)fs, respectively. The multi-photon dynamics leading to these ions differ. CF3I+ corresponds to a (1+2′) transition with one-photon pump excitation to the A band of CF3I. CF3+ are mainly formed by a tow-photon probe excitation to the CF3+ with subsequent dissociation of parent ions. I+ are produced in (2+2′) combined with (1+1′+2′) process. The results provide information on the multi-photon pathways involved. 相似文献