十六烷基三甲基溴化铵光度滴定法测定硫酸外国佬骨素钠盐

建立一种测定硫酸软骨素的新方法。十六烷基三甲基溴化铵在KH2PO4-Na2HPO4缓冲溶液中、乳化剂OP共存下与硫酸软骨素反应形成离子对缔合物，溶液转变成稳定的乳化液。用光度滴定法测定硫酸软骨素。用标准加入法做加收试验，回收率为99.9%-100.2%，相对标准偏差0.32%-0.40%。方法应用于外贸样品测定，结果满意，方法准确、简便、快速。     

鱼翅中硫酸软骨素的酶解-高效液相色谱法测定

建立了一种测定鱼翅中硫酸软骨素的酶解－高效液相色谱方法；该法利用在一定条件下硫酸软骨素能被硫酸软骨素酶ABC定量酶解成软骨素二糖，通过高效液相色谱法测定软骨素二糖的量来计算硫酸软骨素的含量。     

酸水解-柱前衍生化-HPLC-MS/MS法分析三种即食海产品中的酸性多糖

从扇贝丁、鱿鱼丝和鳕鱼片中提取得到粗多糖,使用1.3 mol/L的三氟乙酸(TFA)进行降解,1-苯基-3-甲基-5-吡唑啉酮(PMP)柱前衍生化后,高效液相色谱-三重四级杆质谱(HPLC-MS/MS)分析降解产物中的二糖片段。扇贝丁和鱿鱼丝中的酸性多糖几乎全部为硫酸软骨素;而鳕鱼片不仅含有硫酸软骨素,还含有少量透明质酸,相对含量分别为87.5%和12.5%。     

基于离子液体的反相液相色谱法检测胆碱和四甲基铵

本文发展了以离子液体为流动相添加剂的反相液相色谱分离和间接紫外检测胆碱和四甲基铵的方法。研究了离子液体、甲醇、紫外检测波长等因素对分离、检测胆碱和四甲基铵的影响。用普通的反相色谱柱，以甲醇/1-丁基-3-甲基咪唑四氟硼酸盐水溶液为流动相，在210 nm紫外检测波长下，实现了胆碱和四甲基铵的分离和检测。本方法对分析物的检出限低于0.5 mg/L,标准曲线具有良好的线性关系。将方法应用于植物生长调节剂和桶装水样品的分析，加标回收率为95.1%～99.6%,相对标准偏差小于2.0%。     

问题肝素中多硫酸软骨素杂质的柱前衍生高效液相色谱分析

基于肝素和多硫酸软骨素(OSCS)在单糖组成上的差别,建立了可用于肝素中OSCS检测的柱前衍生高效液相色谱法.采用3 mol/L三氟乙酸,将受污染的问题肝素在110℃下充氮封管水解4 h,在碱性条件下与1-苯基-3-甲基-5-吡唑啉酮进行衍生化反应,再采用C18反相色谱柱,以0.1 mol/L磷酸盐(pH=6.7)缓冲液/乙腈(体积比82∶18)为流动相,在流速1.0 mL/min、柱温25℃及紫外检测波长245 nm的条件下进行液相色谱分析.结果表明,肝素和OSCS的单糖色谱峰具有良好的分离度,测得2批问题肝素中OSCS杂质的质量分数分别为19.6%和28.3%.该方法具有良好的精密度和重现性,易于推广,适合于肝素中OSCS杂质的检测,并可用于硫酸软骨素A和C与硫酸软骨素B的区分和鉴别.     

以离子液体为流动相的高效液相色谱-间接紫外检测法分析四甲基按根离子

建立了四甲基铵根离子的反相高效液相色谱-间接紫外检测分析法.以ZORBAX ODS反相色谱柱为分离柱,采用间接紫外检测方法,考察了紫外检测波长和离子液体+有机溶剂(乙腈、甲醇)流动相对分离和测定四甲基铵根离子的影响.最佳色谱条件为:以80% 1-乙基-3-甲基咪唑四氟硼酸盐水溶液(0.5 mmol/L,乙酸调pH 3....     

甲基紫硫酸软骨素共振瑞利散射光谱及其应用

在Britton-Robinson缓冲介质(pH9.37)中硫酸软骨素与甲基紫反应形成离子缔合物时,共振瑞利散射(RRS)强度会明显增强,其最大RRS峰位于505和661 nm处。本文对反应的最佳条件、影响因素、硫酸软骨素浓度与RRS强度的关系进行了研究,建立起一种快速、简便、灵敏的测定硫酸软骨素的方法。本法在661和505 nm测定波长处的线性范围均为:0.15~0.90 mg/L,其检出限分别为0.019 mg/L(505 nm)和0.043mg/L(661 nm)。该法应用于针剂中硫酸软骨素的测定,结果满意。     

用电活性离子对制成的离子选择电极测定阳离子表面活性剂

制备了3种基于不同电活性物质(十二烷基二甲基苄基铵-四苯硼、十六烷基三甲基铵-四苯硼、十八烷基三甲基铵-四苯硼)的阳离子表面活性剂离子选择电极,并对其性能做了测定,结果显示该类电极对阳离子表面活性剂十二烷基二甲基苄基氯化铵、十六烷基三甲基溴化铵、十八烷基三甲基氯化铵均有能斯特响应。以此类电极作为指示电极,四苯硼钠溶液作为滴定剂,对阳离子表面活性剂(十二烷基二甲基苄基氯化铵、十八烷基三甲基氯化铵、海明1622)进行了活性物含量的测定,与两相滴定法测定结果进行了比较。     

十六烷基三甲基溴化铵光度滴定法测定硫酸软骨素钠盐

建立一种测定硫酸软骨素的新方法。十六烷基三甲基溴化铵在KH2 PO4 Na2 HPO4 缓冲溶液中、乳化剂OP共存下与硫酸软骨素反应形成离子对缔合物 ,溶液转变成稳定的乳化液。用光度滴定法测定硫酸软骨素。用标准加入法做回收试验 ,回收率为 99.9%～ 10 0 .2 % ,相对标准偏差0 .32 %～ 0 .4 0 %。方法应用于外贸样品测定 ,结果满意 ,方法准确、简便、快速     

中性红光度法测定硫酸软骨素含量

硫酸软骨素是一种天然酸性粘多糖，属生物高分子化合物。硫酸软骨素有A、C和D三种异构体，均是由D-葡萄糖醛酸和N-乙酰-D氨基半乳糖组成，只是硫酸基位置不同。硫酸软骨素具有许多重要的生理活性和药理作用，如促进冠状动脉循环、降血脂、抗凝血、抗肿瘤和防止血管硬化等，广泛用于临床、化妆品和医用材料等领域。硫酸软骨素的测定方法有Elson-Morgan反应法，即将硫酸软骨素水解或酶解成氨基己糖，然后在碱性条件下与乙酰丙酮反应，生成色原，再与对二甲氨基苯甲醛的盐酸醇溶液反应产生红色，以盐酸氨基葡萄糖为对照品，用比色法测定。还有高效液相色谱法，天青A和亚甲基蓝吸收光谱法。中性红属于醌亚胺类染料，带正电荷，曾作为生物标记用于做蛋白质和DNA的光谱探针。本文将中性红作为糖类物质的光谱探针，研究了中性红与硫酸软骨素的相互作用，根据其复合物溶液在特定波长处吸光度降低与硫酸软骨素的含量成比例的特点，建立了一种快速、简便、灵敏的测定硫酸软骨素含量的光度法。     

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.     

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.     

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.     

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.