离子排斥色谱法测定有机酸的研究

研究了利用高效离子排斥色谱（ＨＰＩＣＥ）和电导检测器分离和测定有机酸的色谱条件。选用低电导的辛烷磺酸为淋洗液，对８种有机酸的分离条件进行了研究，并将该法应用于化学镀镍液中有机酸的分析，结果令人满意。     

化学镀液中次磷酸根和亚磷酸根的离子色谱测定

在HPIC-AS4A分离柱上选用2.0×10~(-3)mol/L Na_2CO_3作淋洗液分离子微量HPO_3~(2-)和较高含量的H_2PO_2~-,用串联双电导检测器的不同输出范围分别同时定量。本法用于化学镀液中H_2PO_2~-和HPO_3~(2-)的测定,得到满意结果。     

离子排斥色谱法测定十二种有机酸的研究

研究离子排斥色谱法分离/测定有机酸。选用盐酸作淋洗液,以四丁基氢氧化铵为再生液,考察了淋洗液浓度,流量等因素对分离和测定的影响。对十二种有机酸在阴离子排斥色谱柱睥保留待业进行了系统研究,找出了柱分离有机酸的规律。在最佳色谱条件下,测定了白葡萄酒中的有机酸。     

离子色谱法测定一元有机酸

离子色谱法测定了一元有机酸如乳酸、乙酸、乙醇酸、甲酸与丙酮酸,以及F~-离子,对淋洗液的组成进行了选择。以1.5ml/min的0.8mmol/l Na_2CO_3在Dionex HPIC-AS6和AG6上分离,抑制电导检测。其中除乳酸和乙酸由于部分重叠,在5～50μg/ml范围的相关系数为0.998和0.988外,其余物质的峰面积线性相关系数为0.999以上,检测限均低于50ng/ml而线性范围达1000μg/ml以上。用这种方法测定了饮料如黄酒和啤酒中的一元有机酸。     

单柱离子色谱法同时分析无机阴离子和有机酸

1979年Gjerde等提出单柱离子色谱法。用电导检测的单柱阴离子色谱主要用于无机阴离子分析,用于有机酸分析的文献相对较少。本文用邻苯二甲酸氢钾为淋洗液的单柱离子色谱系统,同时分析了六种无机阴离子和四种有机酸。     

离子抑制色谱法同时测定化学镀液中的四种有机酸

HP1100型高效液相色谱仪,配G1316A二极管阵列检测器,HP Chemstation化学工作站（美国安捷伦公司）。有机酸标准品：乙酸、柠檬酸为分析纯,纯度大于99％（西安化学试剂厂）;乳酸为分析纯,纯度为85％（天津市化学试剂六厂,需标定）;氨基乙酸为生化试剂,纯度大于99％（广东汕头市红卫化工厂）。磷酸二氢钠、磷酸为分析纯（西安化学试剂厂）。     

淋洗液自动发生-离子色谱法同时测定食品中的21种有机酸

建立了一种利用离子色谱法同时测定样品中奎尼酸、乙酸、丙酮酸、草酰乙酸、甘露酸、乳酸、琥珀酸、苹果酸、酒石酸、草酸、富马酸、抗坏血酸、α-酮戊二酸、肉桂酸、水杨酸、柠檬酸、异柠檬酸、阿魏酸、顺乌头酸、反乌头酸、β-香豆酸等21种有机酸的方法。样品经提取、脱色、过滤后用IonPac AS11分离柱分离,以EG40自动淋洗液发生器生成的5~34 mmol/L KOH为淋洗液洗脱,抑制电导检测器检测。21种有机酸的浓度与其峰面积在一定的范围内呈良好的线性关系,检出限均低于0.188 mg/L,加标回收率为91.5%~101.8%。该法用于多种食物样品中有机酸的测定,结果令人满意。     

酒石酸合成液中有机酸的双检测器离子色谱法测定及计算

为寻找其最佳工艺条件,须及时分析在各种反应条件下各组分的变化及可能产生的副反应。作者曾用电位滴定计算分析法同时测定合成液中的上述反应式中的三种有机酸(分析一个样品需20min),在某些情况下易受副反应产物的干扰。本文探讨了HPICE法分离、检测酒石酸合成液中各有机酸的条件,提出用电导、紫外双检测器法计算处理解决     

DX-300离子色谱测定山地冰川雪冰中的有机酸与无机酸阴离子

 利用AS4A SC分离柱 ,AG4A SC保护柱 ,ASRS Ⅱ抑制器 ,TAC 2阴离子富集柱和ATC 1阴离子捕集柱 ,以四硼酸钠 (Na2 B4O7)为淋洗液试剂 ,2 5mmol/LH2 SO4为化学抑制的再生液 ,采用梯度淋洗方式 ,对中国天山乌鲁木齐河源一号冰川雪冰中的生物有机酸和无机酸阴离子进行了测试分析。 2mL雪冰融水样品可在 16min内通过一次进样检测出氟离子、乙酸根离子、甲酸根离子、丙酮酸根离子、一氯乙酸根离子、氯离子、亚硝酸根离子、溴离子、硝酸根离子、磷酸根离子、硫酸根离子和草酸根离子共 10多种有机酸和无机酸阴离子。     

烟草中9种有机酸的梯度离子色谱法测定研究

采用淋洗液自动发生一梯度离子色谱分离,电导检测法分离测定了烟草中的甲酸、乙酸、乳酸、丙酸、丁酸、苹果酸、丙二酸、草酸和柠檬酸,并研究了9种有机酸在阴离子交换色谱中的保留行为.以淋洗液自动发生器生成的KOH为淋洗液,样品经提取、过滤稀释后,在IonPac AS1l-HC阴离子交换色谱柱上分离,抑制电导检测器进行检测,一次...     

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.     

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.     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

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.