糖类衍生物在毛细管区带电泳下的分离研究

以新合成的1-萘基-3-甲基-5-吡唑啉酮(NMP)为柱前衍生试剂,采用毛细管区带电泳模式考察并优化了糖类衍生物的分离条件。实验采用58.5cm×50μmi.d.毛细管(有效柱长50cm),55mmol/L硼酸盐缓冲溶液(pH9.46),柱温20℃,分离电压22kV,进样10s,在不加任何添加剂的情况下,高效、快速地实现了9种糖的基线分离,并在最优化条件下进行了唐古特白刺实际样品的分离分析,结果令人满意。     

藏药蕨麻多糖水解单糖的毛细管区带电泳分离研究

以1-萘基-3-甲基-5-吡唑啉酮(NMP)为柱前衍生试剂,探讨了毛细管区带电泳模式下对藏药蕨麻多糖水解液中单糖的分离条件。实验采用58.5 cm×50μm i.d.毛细管(有效长度50 cm),55 mmol/L硼酸盐缓冲溶液(pH=9.46),柱温20℃,分离电压22 kV,进样10 s。该法不加任何添加剂,9种单糖可高效、快速基线分离,实现了对藏药蕨麻多糖水解液中单糖的分离和定量分析,结果令人满意。     

表面活性剂对NBD-Cl衍生氨基酸的荧光增敏和芯片电泳分离的影响

研究多种表面活性剂以及溶剂对4-氯-7-硝基苯-2-氧-1,3-二唑(NBD-Cl)衍生氨基酸荧光性质的影响。考察并优化了NBD-Cl与氨基酸的衍生反应条件以及芯片毛细管电泳-激光诱导荧光的分离分析条件。结果表明:在临界胶束浓度以上,阳离子表面活性剂十六烷基三甲基溴化胺(CTMAB)对精氨酸、谷氨酸、天冬氨酸的NBD-Cl衍生物,非离子表面活性剂十二烷基聚氧乙烯醚(Brij-35)对苯丙氨酸、精氨酸的NBD-Cl衍生物有荧光增敏效果。在含有5mmol/LBrij-35和20%乙腈添加剂的15mmol/L硼砂缓冲液(pH9.2)中,精氨酸、苯丙氨酸、丙氨酸、甘氨酸、谷氨酸及天冬氨酸等6种氨基酸的NBD-Cl衍生物可以在70s内实现分离,其中较难分离的丙氨酸、甘氨酸的NBD-Cl衍生物分离度为0.91;6种氨基酸衍生物的检出限为0.15～1.6μmol/L。     

NDA柱前衍生毛细管电泳高灵敏安培检测组胺

本文提出了毛细管电泳 2,3 萘二甲醛(NDA)柱前衍生高灵敏安培检测组胺的新方法,对衍生反应条件和电泳分析条件,包括衍生试剂浓度、衍生溶液的pH值、衍生反应时间、分离介质的pH值、进样时间和分离电压进行了优化,确定衍生溶液pH值为9.0,NDA浓度为5.0×10-4mol/L,CN-浓度为2.5×10-3mol/L时的衍生效果最佳;10mmol/LTris H3PO4(pH5.0)为最佳电泳缓冲液,检测电位为0.7V(vs.SCE)时,组胺检出限达6.8×10-8mol/L(S/N=3),较不衍生测定法灵敏度提高6倍,为测定痕量组胺提供了一个新方法。     

柱前衍生反相高效液相色谱法测定血清中9种胆汁酸

建立了一种柱前衍生反相高效液相色谱(RP-HPLC)测定血清中9种胆汁酸的方法。以4-溴甲基-7-甲氧基香豆素(BMC)为衍生剂,用Waters Nova C18色谱柱分离,采用甲醇／乙腈和水梯度洗脱,荧光检测,9种胆汁酸在5～40μmol／L范围内具有良好线性,r为0．9988～0．9998。回收率为85．40％～100．45％,检出限为1～2μmol／L。该法灵敏、特效、重复性好,可用于临床血清中微量胆汁酸的测定。     

3-苯基乳酸的手性毛细管电泳拆分

考察了环糊精种类、环糊精浓度、缓冲溶液pH、分离电压、温度等因素对3-苯基乳酸手性分离的影响,并对分离条件进行了优化。结果表明,采用区带毛细管电泳技术,以0.03 mol/L的羟丙基-β-环糊精为手性选择剂,0.1 mol/L的磷酸缓冲溶液(pH 5.5)为电泳缓冲溶液,26 kV的分离电压,在25 ℃下可使3-苯基乳酸对映体达到基线分离,分离度为1.51。     

毛细管胶束电动色谱法分离测定中药半枝莲中的7种有效成分

建立了毛细管胶束电动色谱同时分析检测中药半枝莲药材及其膏剂中黄芩素、柚皮素、汉黄芩素、野黄芩苷、芹菜素、木犀草素和原儿茶酸7种有效成分的方法。半枝莲样品中7种有效成分经甲醇超声提取。实验考察了运行缓冲溶液的pH值和浓度、添加剂、检测波长、分离电压和进样时间等重要参数对目标物分离的影响。得到的优化条件为: 运行缓冲液50 mmol/L硼砂-0.20 mol/L硼酸溶液(pH 8.4),含8.5 mmol/L十二烷基硫酸钠(SDS),分离电压25 kV,检测波长260 nm和335 nm。在此条件下,7种组分于12 min内达到基线分离。各组分在8×10~6～3.2×10~4mol/L范围内呈良好的线性关系,相关系数(r2)为0.9965～0.9999;检出限为7.0×10~8～2.0×10~6mol/L;回收率均大于85%。该方法提取简便、准确可靠、重复性好、灵敏度高,可以用于中药半枝莲中7种有效成分的定量检测。     

毛细管电泳-间接电化学发光法对茶叶中百草枯农药残留的检测

基于农药百草枯对钌联吡啶-三丙胺(TPA)体系的电化学发光具有显著的抑制作用,建立了毛细管电泳-间接电化学发光检测茶叶中残留农药百草枯的新方法.讨论了初始电位、钌联吡啶和TPA浓度、进样电压、进样时间、运行缓冲溶液的浓度与pH值等条件对百草枯检测灵敏度的影响.确定最佳实验条件为1.20 V初始电压、0.7 mmol/L钌联吡啶、0.6 mmol/L TPA、9 kV进样电压、9 s进样时间、35 mmol/L磷酸盐(pH 8.5)为运行缓冲溶液.在优化实验条件下,百草枯浓度在5×10~(-7) 5×10~(-5)mol/L范围内呈良好线性(相关系数为0.994 5),检出限为9.4×10~(-8) mol/L.对5×10~(-5) mol/L百草枯标准溶液连续测定5次,相对峰高与迁移时间的相对标准偏差分别为3.7%和2.1%.该方法对2.0×10~(-6)、1.0×10~(-5) mol/L百草枯标样的萃取回收率分别为74%和83%,相对标准偏差分别为15%、4.2%(n=5).     

咔唑-9-乙基氯甲酸酯柱前衍生氨基酸胶束电动色谱分离

采用一种新型紫外、荧光衍生试剂咔唑-9-乙基氯甲酸酯对9种氨基酸(丝氨酸、苏氨酸、甘氨酸、谷氨酸、天冬氨酸、缬氨酸、异亮氨酸、亮氨酸、苯丙氨酸)进行柱前衍生,采用胶束电动色谱模式在14 min内完成分离。分离条件：以pH 9.0的 20 mmol/L硼酸盐-30 mmol/L十二烷基硫酸钠(SDS)溶液（含3%(体积分数)乙腈)为缓冲溶液,柱温25 ℃,分离电压18 kV,紫外检测波长214 nm。该方法的线性范围为0.025~0.25 mmol/L,检出限为2.15~2.46 μmol/L。     

柱前衍生化/毛细管电泳法测定阿伦膦酸钠

建立了一种以对甲氧基苯磺酰氯为紫外衍生试剂柱前衍生,毛细管电泳法测定阿伦膦酸钠的分析方法。阿伦膦酸钠与对甲氧基苯磺酰氯的衍生条件为:在20 mmol/L的硼酸盐缓冲溶液(pH 11.5)中,摩尔比为1:10的阿伦膦酸钠与对甲氧基苯磺酰氯在50℃下反应10 min。将衍生产物在毛细管电泳上进行分离,使用pH 9.3 20 mmoL/L的硼酸盐缓冲溶液为分离缓冲体系,柱温25℃,分离电压20 kV,在0.5 psi压力下进样5 s,以二级管阵列(DAD)检测器在233 nm处进行检测。测得阿伦膦酸钠的线性范围为1.0~400μg/mL,检出限为0.5~1.0μg/mL。方法用于药物制剂阿伦膦酸钠片和尿液介质中阿伦膦酸钠的测定,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.     

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.     

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.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.