PEG-无机盐双水相体系萃取水榆花楸叶中总黄酮

水榆花楸叶中所含的黄酮类化合物具有一定的药用价值,利用双水相技术萃取水榆花楸叶中的黄酮是一种有效的分离纯化方法。本文考察了不同种类的无机盐与不同相对分子量的PEG组成的双水相体系的两相性质,研究了PEG1000-Na_2SO_4双水相体系中分离纯化水榆花楸黄酮时PEG的质量分数、Na_2SO_4的质量分数、温度、p H、KCl添加量这5个因素对分配行为的影响,并通过正交实验优化了试验条件。结果表明最佳双水相萃取条件为:Na_2SO_4的质量分数为15%,PEG1000质量分数为30%,p H为9,提取温度为25℃,KCl的添加量为3%,此时原料中黄酮的萃取率可高达97.01%。因此,该体系是一种高效分离纯化水榆花楸叶中黄酮的方法。     

聚合物/磷酸盐双水相分离乳清分离蛋白中α-乳白蛋白和β-乳球蛋白条件的优化

建立了基于聚(乙二醇-ran-丙二醇)单丁基醚(聚合物)与磷酸盐、氯化钠的双水相体系对乳清分离蛋白(WPI)中的α-乳白蛋白(α-LA)和β-乳球蛋白(β-LG)进行分离,并对其分离条件进行了优化.系统地研究了双水相体系pH值、聚合物与KH2PO4溶液体积比、NaC1添加量和WPI浓度对α-LA和β-LG的分离效果的影响,采用液相色谱法对α-LA和β-LG的分离效果进行评价.结果表明,聚合物/KH2PO4双水相体系pH=4.0,40％ (m/m)聚合物与15.5％ (m/m)KH2PO4的体积比为4 mL∶4 mL,NaCl添加量为0.40 g/10 mL,WPI浓度为1 mg/mL时,α-LA和β-LG分离效果最好,上相中α-LA的萃取率为98.2％,下相中β-LG的萃取率为96.6％.     

甲醇-磷酸氢二钾-水双水相萃取-高效液相色谱检测肉类产品中四环素类残留

以甲醇-无机盐-水双水相体系,建立了一种高效的用于液相色谱法检测肉类产品中四环素类抗生素残留的样品前处理方法。实验考察了双水相的形成条件以及对四环素类药物的提取效率,用液相色谱法与瑞利散射法研究了蛋白质对甲醇-无机盐-水双水相体系萃取四环素的影响。结果表明,只有加入适量的磷酸氢二钾才能形成甲醇水双水相体系,该双水相体系对极性较强的四环素类药物具有较高的萃取效率;体积分数为70%的甲醇水溶液作为萃取液可以使肉类产品中的蛋白质基质发生缓慢而彻底地变性,有利于释放与蛋白质结合的药物。由于甲醇-K_2HPO_4-水双水相体系的上相萃取液中水溶性蛋白等杂质较少,样品净化步骤大大简化,在上相中加入少量PSA与C_(18)固体吸附剂,离心后取上清液即可进行HPLC分析。该方法用于肉类产品牛肉、鱼肉中四环素残留的萃取测定,回收率为76.8%~98.2%,检出限为0.039~0.084μg·g~(-1)。     

双水相萃取结合液相色谱法分离蛋白质

建立了PEG/( NH4)2SO4双水相体系萃取富集,结合液相色谱分离分析多种蛋白质的方法.考察了无机盐种类和浓度、PEG分子量、pH值和温度等因素对双水相形成以及对细胞色素C、肌红蛋白、牛血清白蛋白、溶菌酶、胰蛋白酶分配行为的影响.结果表明,上述5种蛋白在室温、pH 3.5～9.0范围内,可在15％ PEG-4000/10％ (NH4)2SO4双水相体系中得到富集,且主要集中在下相.同样条件下,血清中的高丰度蛋白在上下相均有分配,下相分配量较大.通过双水相萃取分离蛋白质及对液相色谱一定时间段的色谱峰收集,可初步实现血清中高丰度蛋白质的分离去除.     

米曲霉氨基酰化酶在聚乙二醇/盐双水相系统中的分配

本文对氨基酰化酶在由聚乙二醇/盐组成的双水相系统中的分配进行了研究。氨基酰化酶在双水相系统中的分配系数受系统中聚乙二醇平均分子量及浓度、盐的种类及浓度、pH值、外加盐及带电聚乙二醇等因素的影响。它为大规模提取纯化氨基酰化酶提供了一种有希望的方法。     

十四烷基三甲基氯化铵/十二烷基苯磺酸钠混合表面活性剂双水相体系的萃取性能

研究了十四烷基三甲基氯化铵(TTAC)与十二烷基苯磺酸钠(SDBS)混合表面活性剂水溶液双水相体系的分相情况、萃取性能及两相的微观结构.结果表明,TTAC/SDBS混合表面活性剂水溶液在30℃下能够形成稳定的双水相体系;该双水相体系对亚甲基蓝、靛红都具有一定的萃取分离作用.其上、下两相的微观结构明显不同,这是其能够形成稳定双水相体系且具有萃取作用的重要原因.     

异丙醇-(NH4)_2SO_4-H_2O双水相体系样品前处理结合GC/MS测定化妆品中苯系物

本文用异丙醇-(NH_4)_2SO_4-H_2O双水相体系高效提取化妆品中的苯系物(BTEX,苯、甲苯、乙苯、对二甲苯、间二甲苯和邻二甲苯),结合气相色谱-质谱联用(GC-MS)实现了对化妆品中六种BTEX的快速准确测定。实验主要考察了双水相体系的形成条件,并探讨了双水相体系对BTEX的萃取效率。实验结果表明:异丙醇不仅具有较好的破乳性能,而且对样品中BTEX有较高的提取效率;硫酸铵具有较好的盐析分相作用;化妆品中BTEX的萃取率与异丙醇水溶液的体积分数有关,当双水相体系中水与异丙醇的体积之比约为3∶2时,异丙醇与化妆品中的BTEX可接触充分,萃取率较高。该方法对化妆品中BTEX的测定回收率为81.1~98.2%,检出限为1.1~3.9 ng·g。     

智能聚合物的双水相体系在生物分子分离纯化中的应用*

简单地改变智能聚合物组成的双水相体系的外界条件,如温度、酸度、离子强度、光照强度、电场、磁场强度等,就可使成相聚合物与生物分子分离。基于智能聚合物的双水相体系分离过程简单,聚合物材料易于回收。近年来,以智能聚合物组成的双水相体系在分离纯化生物分子的研究中发展迅速。本文简要介绍了双水相萃取的原理,综述了十多年来温度敏感型、酸度敏感型、光敏型和具有亲和功能的双水相体系和双水相萃取与其他相关技术的结合在生物分子分离纯化中的研究进展。     

离子液体双水相技术萃取头孢呋辛酯及其机理探究

通过研究离子液体四氟硼酸1-丁基-3-甲基咪唑( [Bmim]BF4)-Na2-CO3双水相体系对头孢呋辛酯的萃取性能,建立了萃取环境水样中头孢呋辛酯的双水相法.考察了双水相体系组成及相关条件对萃取率的影响,并对其萃取作用力及萃取机制进行了探索.结果表明,Na2CO3用量为0.8～2.0 9,[Bmim]BF4用量为1～2 mL时,随着二者用量的增加,萃取率有所增加.与[Bmim]C1/Na2CO3双水相体系相比,[Bmim]BF4/Na2CO3双水相体系更适于萃取头孢呋辛酯.热力学参数AG°T＜0,AH°r＞0,△S°T＞0,说明萃取过程的主要推动力为疏水性相互作用.在最佳萃取条件下,用此方法萃取环境水样中的头孢呋辛酯,二次萃取率大于93％,重现性好.整个萃取过程快速、高效且无乳化现象.     

聚乙烯吡咯啉酮－盐－水液－固萃取体系分离纯化α－淀粉酶的研究

本文研究了α－淀粉酶、酪蛋白、牛血清白蛋白在聚乙烯吡啉酮－盐－水液－固萃取体系中的萃取行为，着重讨论了ｐＨ值、（ＮＨ４）２ＳＯ４浓度及激活剂ＮＳＣ１对酶萃取率的影响。实．验结果表明，在一定条件下，酶大部分被萃入聚合物固相，而杂蛋白则主要分布在盐水相。用该体系分离纯化α－淀粉酶，平均酶活力收得率达９８．９％，一次纯化倍数１．５１。     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

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.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

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.