高效液相色谱分析法测定色氨酸对映体

采用高效液相色谱法,以手性冠醚Crownpak CR( )为固定相、高氯酸溶液/甲醇混合溶液为流动相,成功地实现了色氨酸(Trp)对映体的色谱分离.考察了流动相中甲醇含量、流量和柱温等因素对分离效果的影响.研究表明,适当提高流动相中的甲醇含量、降低流动相流量、降低柱温可以有效地提高分离度.另一方面,提高流动相中的甲醇含量、提高流动相流量、升高柱温可以显著地缩短样品的保留时间.确定了一种最佳分析分离条件,即流动相为甲醇∶高氯酸溶液=15∶85(V/V),流动相流量0.8 mL/min,柱温20℃,波长220 nm,在此条件下进行色谱分离,样品的保留时间小于12 min,分离度达到2.06.该方法具有快速、高效、准确和精密度高等优点.     

高效液相色谱手性流动相添加剂分离西孟坦对映体

以 β 环糊精作为手性流动相添加剂 ,研究了DL 西孟坦在反相HPLC系统中的拆分。考察了缓冲盐的浓度、pH、β 环糊精的浓度、流动相中甲醇的比例、流动相流速和温度对手性分离的影响 ,建立了 β 环糊精动态手性固定相法分离西孟坦对映体的方法。色谱条件为 :ZirchromKromasilODS 1(5 μm ,15 0mm× 4 .6mm)色谱柱 ,流动相为 2 0mmol/L磷酸盐缓冲液 (pH 6 .0 )含 12mmol/Lβ 环糊精∶甲醇 (70∶30 ,V/V) ,流速为 0 .8mL/min ,温度为 17℃。DL 西孟坦对映体的保留时间分别为 2 2 .5和 2 4 .5min ,分离度为 1.5 7。     

直接电导检测离子排斥色谱法测定C1～C6脂肪族有机酸

建立了直接电导检测离子排斥色谱分离测定C1~C6脂肪族有机酸(甲酸、乙酸、丙酸、丁酸、戊酸、己酸)的方法。以Shim-pack SCR-102H 色谱柱为分离柱,选用p-甲苯磺酸水溶液为流动相,考察了流动相中p-甲苯磺酸的浓度、流速、pH、色谱柱温度对分离和测定脂肪族有机酸的影响,确定了最佳的色谱条件为：0.2 mmol/L p-甲苯磺酸水溶液作为流动相,流速1.2 mL/min,柱温45 ℃。所测有机酸的检测限为0.03～0.99 mg/L,相对标准偏差在2.3%以下(n= 5),回收率为91.2%～105.6%,整个分析过程在28 min内完成。该法用于白酒样品的分析,结果令人满意。     

直接进样-液相色谱/串联质谱法测定水中苦味酸

采用液相色谱/串联质谱法测定了水中的苦味酸,对流动相、流速、柱温及进样量等条件进行了优化。结果表明,流动相为甲醇和0.1%甲酸溶液(80∶20,V/V),流速1.0 mL/min,色谱柱柱温40℃,进样量5μL,苦味酸含量在1.0~50μg/L时,校准曲线呈线性关系,相关系数r=0.9999,方法检出限为0.10μg/L。对实际水样进行分析,测量的回收率为76.2%~109%,样品加标平行测定,RSD(n=6)为2.8%~4.7%。     

使用大环糖肽抗生素键合固定相高效液相色谱法直接拆分卡巴拉汀

采用高效液相色谱法在大环糖肽抗生素键合固定相手性柱上拆分了卡巴拉汀(Rivastigmine)对映体。考察了甲醇∶乙酸∶三乙胺流动相体系中乙酸和三乙胺的浓度和比例、有机酸的种类、分离温度及流动相流速对拆分结果的影响。选定的色谱条件为:Chirobiotic V手性柱(250mm×4.6mmi.d.,5μm),流动相为V(甲醇)∶V(乙酸)∶V(三乙胺)=100∶0.02∶0.01,柱温5℃,流速0.5mL/min,检测波长274nm。在柱温5~30℃范围内测定lnα与1/T呈线性关系:lnα=ΔΔH0/RT ΔΔR0/R。     

高效液相色谱法测定苹果中的酚类物质

利用高效液相色谱法分析了红星、秦冠、小国光、黄元帅和富士 5个苹果品种果皮和果肉中小分子酚类物质的分布情况。色谱柱为C1 8柱 ( 1 5 0mm× 4 .6mm ,Φ5 μm) ,流动相为甲醇和水 ,柱温为 30℃ ,流速为 1 .2mL min,线性梯度洗脱 ,紫外检测器波长为 2 80nm。在此色谱条件下 ,各组分均得到良好分离。标准样品的线性范围为 0 .9983～ 0 .9999,平均回收率为 75 %～ 91 %。     

用非手性衍生化法提高肾上腺素类药物在手性固定相上的分离度

建立了高效液相色谱法分离肾上腺素、去甲肾上腺素、异丙肾上腺素的苄氧羰基衍生物对映体的方法.以氯甲酸苄酯为衍生化试剂,在室温、碱性条件下,对3种肾上腺素类药物进行衍生化反应.采用手性CHIRALPAKAD-RH色谱柱,在检测波长为226 nm条件下,考察了流动相、流速、柱温对对映体手性分离的影响.结果表明,肾上腺素、去甲肾上腺素、异丙肾上腺素衍生物对映体分别在乙醇为流动相、流速为0.5 mL/min、柱温为25 ℃;甲醇-乙醇(体积比3:1)为流动相、流速为1.0 mL/min、柱温为25 ℃;甲醇-水-四氢呋喃(体积比150:20:7)为流动相、流速为0.5 mL/min、柱温为25 ℃时,分离效果最佳.     

替考拉宁键合手性固定相高效液相色谱法直接拆分泮托拉唑钠对映体

以替考拉宁为手性选择剂制备了大环抗生素类手性固定相替考拉宁键合手性固定相(T-CSP),建立了T-CSP反相液相色谱直接拆分泮托拉唑钠对映体的方法。考察了流动相中有机改性剂的种类和比例、柱温以及流动相流速对拆分泮托拉唑钠对映体的影响。研究发现,用甲醇作有机改性剂比乙腈更有利于对映体的分离;在研究的温度范围内,随着柱温的升高,对映体的保留时间缩短,同时分离因子和分离度降低;在一定范围内降低流速有利于对映体的分离。采用T-CSP色谱柱(150 mm×4.6 mm i.d.,5 μm),以甲醇-水(体积比为35∶65)为流动相,在流速0.6 mL/min、检测波长290 nm、柱温20 ℃的条件下,泮托拉唑钠对映体获得了近于基线的分离,所建立的方法具有简便快速及重复性好等优点。     

酰胺型手性固定相直接拆分克仑特罗对映体

 将酰胺型手性固定相用于正相高效液相直接拆分 β2 受体兴奋剂克仑特罗。讨论了三元流动相中正己烷、1,2 二氯乙烷和甲醇含量的变化以及柱温和流速对分离的影响 ;优化了实验条件 :流动相为V(正己烷 )∶V(二氯乙烷 )∶V(甲醇 ) =5 4∶38∶8,柱温为 17℃ ,流速为 1 0mL/min ;并对拆分的机理加以探讨。方法简单、快速。     

咪唑离子液体用于反相色谱流动相添加剂分析苯甲酸和山梨酸

开展了咪唑离子液体用于反相色谱流动相进行苯甲酸和山梨酸分析的研究。考察了咪唑离子液体种类与浓度、甲醇浓度、紫外检测波长等因素对分离、检测苯甲酸和山梨酸的影响,并探讨了2种分析物的保留规律。建立了以咪唑离子液体为流动相添加剂的反相色谱测定苯甲酸和山梨酸的分析方法。采用Agilent ZORBAX ODS反相色谱柱,以甲醇-0.2 mmol/L氯化1-丁基3-甲基咪唑水溶液(40∶60,体积比)为流动相,紫外检测波长230 nm,流速1.0 mL/min,色谱柱温度35℃时,可在7.0 min内实现苯甲酸和山梨酸的分离和检测。苯甲酸和山梨酸的线性范围为1.0～100.0 mg/L,相关系数(r)高于0.999 5,检出限均为0.02 mg/L。将方法应用于饮料样品中苯甲酸和山梨酸的测定,加标回收率为93.9%～104%,相对标准偏差(RSD)不大于4.0%,满足定量分析的要求。     

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.