乙醇水溶液析相萃取分离和富集TlCl4-

研究了乙醇-(NH4)2SO4-罗丹明B体系析相萃取和富集Tl(Ⅲ)的行为及与一些金属离子分离的条件。(NH4)2SO4能使乙醇的水溶液分成两相,在分相过程中,TlCl4-与罗丹明B(RhB)生成的[TlCl4-][RhB+]能被乙醇相完全萃取。当溶液中罗丹明B,(NH4)2SO4和乙醇分别为0.28 mg/mL,0.30 g/mL和质量分数30%时,Tl(Ⅲ)的萃取率达到97.9%以上,Co(Ⅱ),Pb(Ⅱ),Fe(Ⅲ),Mg(Ⅱ),Ru(Ⅲ),Ni(Ⅱ),Cr(Ⅲ),Ag(Ⅰ)和Cu(Ⅱ)基本不萃取,实现了Tl(Ⅲ)与上述金属离子的分离。方法已应用于合成水样中Tl(Ⅲ)的分离和测定。     

PEG 800-Tween 80-(NH4)2 SO4-H2O双水相萃取紫外分光光度法测定银杏叶中的芦丁

采用聚乙二醇(PEG800)与吐温80(Tween80)组合表面活性剂、(NH4)2SO4、H2O形成双水相体系,研究芦丁在该双水相体系中的分配行为。用紫外分光光度法测定银杏叶中芦丁的含量。该体系对芦丁的平均萃取率为95．0％,测定芦丁浓度的线性范围为0～50ug／mL,相关系数r=0．9995。用该法对银杏叶中的芦丁进行测定,测定结果的相对标准偏差为3．1％,回收率为96．5％～105．2％。     

荧光分光光度法测定阿司匹林中游离水杨酸——PEG 1500-OP-(NH4)2SO4-H2O双水相体系萃取分离

提出了由聚乙二醇(PEG) 1500-OP-(NH,4),2SO,4 及少量水组成的双水相萃取体系并应用于从阿司匹林基体中萃取游离水杨酸.对试验条件作了系统试验,取得如下优化条件:① PEG1500(500 g·L-1)溶液及 OP(500 g·L-1)溶液的体积(mL)比为PEG:OP=2.50:1.50;②固体(NH,4),2SO,4-H,2O的加入量为 2.0 g;③加入 pH 6.0 的 B-R 缓冲溶液至总体积约为 10 mL.按此条件测得水杨酸的萃取率为 98.6%.萃取后,将上层液(即表面活性剂相)移至 10 mL 容量瓶中,加B-R 缓冲溶液至 10.0 mL,在λ,ex为305 nm,λ,em为 392 nm 波长条件下测定溶液的荧光强度.应用此方法分析了3件阿司匹林试样,每一个试样分析 10 次,所得结果的相对标准偏差(n=10)在1.7%～2.1%之间.在此样品的基础上加入水杨酸标准溶液进行回收率试验,所测得回收率在93.3%～103.3%之间,其相对标准偏差(n=5)≤2.5%.     

超高压提取桑叶芦丁

考察了常温下超高压提取桑叶芦丁的提取工艺,观察了不同提取溶剂、提取压力、溶剂与原料比、提取时间及桑叶颗粒大小等因素对桑叶芦丁提取率的影响,并对提取工艺进行了优化。桑叶芦丁的最佳萃取条件为:70%乙醇水溶液为提取溶剂,提取压力为500MPa,提取时间为8min,桑叶颗粒大小为0.18～0.25mm,溶剂与原料比为20∶1,桑叶芦丁提取率达23.9mg/g。     

醇与离子液体二元双水相体系萃取盐酸多西环素

基于小分子醇双水相体系和离子液体双水相体系,建立了正丙醇与亲水性离子液体1-丁基-3-甲基咪唑四氟硼酸[Bmim]BF4和(NH4)2SO4形成的二元双水相体系萃取盐酸多西环素的新方法。考察了(NH4)2SO4含量、正丙醇用量、pH值、离子液体含量以及盐酸多西环素含量对盐酸多西环素分配行为的影响。结果表明:当醇和离子液体二元双水相体系的pH值在4.0～5.0范围内,(NH4)2SO4含量为34%,且盐酸多西环素的质量浓度在25～95 mg/L之间时,该体系对盐酸多西环素的萃取率可达90.26%～95.71%,分配系数可达62.452～149.401。     

分光光度法研究水-乙醇体系析相萃取分离和富集PdBr_4~(2-)

用可见分光光度法研究了水-乙醇体系析相萃取分离和富集PdBr42-的行为及与一些金属离子分离的条件.结果表明,(NH4)2SO4能使乙醇的水溶液分成两相,在分相过程中,Pd(Ⅱ)与KBr生成的PdBr42-与质子化乙醇(C2H5OH2+)形成的缔合物[PdBr42-][C2H5OH2+]2能被乙醇相完全萃取.当乙醇、KBr和(NH4)2SO4分别为30%、6.0×10-3 mol/,L、0.3 g/mL,pH 3时,PdBr42-的萃取率达到98.6%以上,Fe(Ⅲ),Al(Ⅲ),Cr(Ⅲ),Ag(Ⅰ),Cu(Ⅱ),Ni(Ⅱ),Zn(Ⅱ),Co(Ⅱ),Mn(Ⅱ),V(Ⅴ),U(Ⅵ),Pb(Ⅱ),Ru(Ⅲ),Rh(Ⅲ)和Hg(Ⅱ)基本不被萃取,实现了Pd(Ⅱ)与上述金属离子的分离.     

无机盐存在下双水相体系萃取分离碘-乙基紫-镉(Ⅱ)缔合物

研究了在丙醇-水体系中加入表面活性剂乙基紫(EV)后,影响Cd2 分离的酸度、无机盐、卤离子种类等条件。实验表明,(NH4)2SO4存在下,无表面活性剂EV,一定量的I-,在酸性条件下,Cd2 的萃取率为68%,而同样条件下,加入mg级表面活性剂EV后,Cd2 与EV、г形成三元缔合物,被均相萃取、异相分离;缔合物进入丙醇相,Cd2 被完全萃取分离;在pH 1.0时,试验了Cd2 加入量为5μg/mL时与Fe3 、Co2 、Ni2 、Zn2 、Mn2 、Zn2 、Cr3 的二元或多元离子混合液的分离试验,分离完全。     

聚乙二醇-硫酸铵双水相萃取次甲基蓝的研究

利用分光光度法研究了次甲基蓝在聚乙二醇-硫酸铵双水相体系的萃取行为,探索了质量配比(mPEc/m(NH4)2SO4)、温度和次甲基蓝的浓度对双水相及次甲基蓝萃取率(Y)的影响.实验表明:(1)在一定的温度和浓度下,随着mPEC/m(NH4)2SO4的减小,分配系数K( cup/clow)增加,萃取率Y略有减小;(2)在一定的质量配比和浓度下,分配系数K(cup/clow)随温度的升高而增大,但萃取率Y却基本保持不变;(3)在一定的质量配比和温度下,随着次甲基蓝浓度的增加,分配系数K(cup/clow)增大;萃取率Y略有增加.在mPEG/m( NH4) 2SO4为1.50∶1,c次甲基蓝=8.915×10-5mol/L、t=30℃的实验条件下,K(cup/clow)=22.14,萃取率(y)可达95.43％.     

基于整体材料的固相萃取与毛细管电泳技术联合分离检测桑叶中的多酚类物质

采用甲基丙烯酸丁酯(BMA)为单体、乙二醇二甲基丙烯酸酯(EDMA)为交联剂,合成了聚甲基丙烯酸丁酯-乙二醇二甲基丙烯酸酯(poly(BMA-co-EDMA))整体柱,并将其作为固相萃取整体柱与毛细管电泳联用,建立了桑叶中芦丁、绿原酸、槲皮素等多酚物质的分离检测方法。考察了固相萃取条件如淋洗液种类、淋洗液流速和体积、洗脱液种类对萃取效率的影响,并采用毛细管电泳进行分离分析。结果显示,芦丁、绿原酸、槲皮素均在10～160μg/mL范围内线性关系良好,相关系数分别为0.995 5、0.998 5、0.999 5,检出限分别为4.65、1.12、3.49μg/mL,相对标准偏差分别为2.4%、0.98%、2.8%,平均回收率分别为94.7%、98.9%、102%。该固相萃取柱能有效富集和纯化桑叶中3种多酚物质。方法简便、快速、灵敏,适用于桑叶中3种多酚类物质的分离分析。     

Co(Ⅱ)-4-(2-吡啶偶氮)间苯二酚-聚乙二醇-(NH4)2SO4萃取体系的研究和应用

研究了Co(Ⅱ)-4-(2-吡啶偶氮)间苯二酚(PAR)-聚乙二醇(PEG)-(NH4)2SO4体系的萃取行为及最佳分相条件,建立了测定生物样品中微量钴的非有机溶剂萃取光度法。结果表明,在pH 8.6的六次甲基四胺缓冲溶液中,在(NH4)2SO4存在下,Co(Ⅱ)-PAR的络合物可被PEG相富集萃取。在PEG相中络合物的最大吸收波长为519 nm,表观摩尔吸光系数4.68×104L.mol-1.cm-1,钴量在0~1.8μg/mL范围内服从比尔定律。方法已用于粮食、茶叶等生物样品中痕量钴的测定,回收率97.2%~103%。     

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.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.