悬浮液进样-火焰原子光谱法测定烟叶中的钾锰

用悬浮液技术处理烟叶样品 ,即将样品烘干、粉碎、过筛 ,并悬浮在 1 .5g L琼脂溶液中制成均匀的悬浮液。以钙作为锰的释放剂和以钡作为钾的消电离剂。用工作曲线法测定 ,以火焰原子发射法 (FAES)测定钾 ,以火焰原子吸收法 (FAAS)测定锰。建立了快速测定烟叶中钾、锰的FAS法。对化学干扰、介质的影响及检出限进行了考察。测定结果的相对标准偏差 <2 .4% ,测定结果与灰化法一致 ,相对误差 <± 2 .5 %。     

非完全消化悬浮液进样火焰原子光谱法测定木耳中钾铜锌

将非完全消化法与悬浮液进样技术相结合处理木耳样品 ,即在加热下用浓硝酸消解样品 ,使绝大部分样品组分进入溶液 ,再加入乳化剂OP溶液及琼脂溶液将极小部分的不溶物悬浮成悬浮液 ,用吸收法测定铜、锌 ,以发射法测定钾。建立了测定木耳中钾、铜和锌的快速火焰原子光谱法。工作曲线法的测定结果与灰化法一致 ,相对误差小于± 2 .6% ,t检验表明此法与灰化法之间无显著性差异。方法简便、快速、准确     

火焰原子吸收光谱法测定猪肝中铜铁锌

用悬浮液技术及非完全消化法分别处理猪肝样品,建立了悬浮液技术和非完全消化-火焰原子吸收光谱法快速测定猪肝中铜、铁、锌的分析方法。试验表明,在悬浮液中加入适量盐酸可显著提高被测元素的吸光度,试液的粘度与空白溶液的一致,无背景吸收干扰。对非完全消化法样品处理条件、悬浮液的稳定时间及酸的影响进行了考察。相对标准偏差小于4.0%,测定结果与灰化法一致,相对误差小于±1.8%(悬浮液法),±2.7%(非完全消化法)。     

超声搅拌悬浮液进样FAAS法测定铁皮石斛(枫斗)中的铜

研究了铁皮石斛 (枫斗 )中铜的分析方法。样品在 80± 2℃烘干 4h ,研磨过 2 0 0目筛 ,然后加入 5mL 0 1 5 %琼脂悬浮液 ,用超声搅拌混匀后直接上机测定。测定结果与传统湿法一致 ,t检验表明两者无显著性差异 ,相对误差小于 0 96%。该法简便、快速、准确。     

Determination of Iron, Zinc and Calcium in Chinese Medicinal Herb by Suspension Sampling

将悬浮液进样技术应用于火焰原子吸收光谱法,建立了中草药中微量元素的快速分析新方法。将样品粉碎、悬浮在琼脂胶体中制成悬浮液;取适量样品悬浮液配制成试液,喷入空气－乙炔火焰,用标准加入法测定。用该法成功地测定了当归、川芎及川乌中的铁、锌、钙,测定结果与灰化法一致,方法简便、快速、准确。     

中草药中铁锌钙的悬浮液进样-火焰原子吸收光谱法测定

将悬浮液进样技术应用于火焰原子吸收光谱法, 建立了中草药中微量元素的快速分析新方法。将样品粉碎、悬浮在琼脂胶体中制成悬浮液; 取适量样品悬浮液配制成试液, 喷入空气－ 乙炔火焰, 用标准加入法测定。 用该法成功地测定了当归、川芎及川乌中的铁、锌、钙, 测定结果与灰化法一致, 方法简便、快速、准确。     

悬浮液进样-火焰原子吸收光谱法测定聚乙烯中的铜、镁

将悬浮液进样技术应用于火焰原子吸收光谱法成功地测定了聚乙烯中的镁、铜。将样品粉碎、过筛并悬浮在乙醇-Triton X-100溶液中制成悬浮液。通过在与样品悬浮液等体积的空白溶液中加入适量的乙二醇，可配制成与试液粘度一致的参比溶液。以Sr^2 作为镁的释放剂，以正丁醇为增敏试剂，用工作曲线法检测定。对悬浮剂的选择、干扰、线性范围及检出限进行了考察，方法简便、快速、准确。     

悬浮液进样-火焰原子吸收光谱法测定中草药中的微量铜

将悬浮液进样技术应用于火焰原子吸收光谱法,建立了快速测定中草药中微量铜的新方法。将样品磨细,制成悬浮液,喷入空气－乙炔火焰,以空白溶液为参比,用氘灯进行背景和扣除,以标准加入法测定。测定结果与灰化法一致,两种方法的相对误差小于±３．６％,ＲＳＤ小于２．５％,检出限为０．０５７ｍｇ／Ｌ。     

悬浮液技术-火焰原子吸收光谱法测定明胶中钙镁

用悬浮液技术处理明胶样品。将样品烘干、粉碎、过筛,制备成琼脂悬浮液。取适量样品悬浮液加入释放剂Sr2+配制成试剂,喷入空气-乙炔火焰进行测定,建立了悬浮液技术-火焰原子吸收光谱法快速测定明胶中钙、镁的分析方法。以空白溶液为参比,用工作曲线法测定。对琼脂溶液用量、化学干扰、试液与空白溶液粘度一致性、背景吸收干扰及检出限进行了考察。测定结果与灰化法一致,相对误差小于±0．9％,相对标准偏差小于5．2％。方法简便、准确。     

悬浮进样原子吸收法测定茶叶中的微量元素

用悬浮液技术处理茶叶样品,即将样品烘干、粉碎、过筛,并悬浮在1.5g/L琼脂溶液中制成均匀的悬浮液,建立了火焰原子吸收快速测定茶叶中微量元素的方法。该法快捷、简便、具有良好的精密度和准确度,应用于实际样品的测定结果满意。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).