化学计量学方法用于多环芳烃液相色谱分离条件优化

本文报道化学计量学方法用于多环芳烃(PAHs)液相色谱分离条件的优化.使用均匀实验设计法,以乙腈在线性梯度展开时的初始浓度和线性梯度的斜率为优化参数,对16种多环芳烃混合体系进行液相色谱分离条件优化,采用遗传算法和退火神经网络方法建立了有效的分离条件预测模型.对模型所预测的最佳分离条件进行试验,分离结果满意.     

退火遗传算法在液相色谱线性梯度分离条件优化中的应用

对于复杂样品的反相高效液相色谱分离,一般需在不同的流动相洗脱模式下进行。流动相线性梯度淋洗在分离方法发展中得到了广泛的应用。遗传算法作为一种新的全局优化搜索算法,已广泛应用于计算机科学等领域、作者也已成功地将遗传算法应用于液相色谱分离条件优化。本文将模拟退火演化方法引入遗传算法,并将退火遗     

反相高效液相三元流动相台阶梯度分离条件的快速优化方法

 根据溶质在柱内的迁移规律 ,建立了一种利用线性梯度实验快速获得溶质保留值方程系数 ,然后以串行响应函数为优化指标进行多台阶梯度分离条件优化的方法。与利用等度实验获得保留值方程的方法相比 ,该法可以大大缩短优化时间。通过该方法对芳香胺和衍生化氨基酸样品进行了分离 ,获得了满意的分离度 ,表明该方法的预测精度很好。     

反相高效液相色谱中复杂体系二元多台阶梯度分离条件快速优化方法

提出了一种反相高效液相色谱中二元多台阶梯度分离条件快速优化方法。通过数次线性梯度初始实验，求得溶质的保留方程。在此基础上，利用重叠分离区域图（OSRM）方法，快速求得复杂样品的最佳多台阶梯度分离条件。该方法只需要几个小时就可以完成对复杂样品分离条件的优化，并通过对中药川芎提取物的分离加以验证，获得了较好的预测精度和分离效果。     

基于分离度图的HPLC线性多阶梯优化策略

基于色谱保留机理(保留与流动相条件之间的关系)和分离度图方法, 根据对于样品分离要求的不同, 提出了对多阶梯线性梯度液相色谱洗脱条件进行优化的三种策略, 也通过文献数据进行模拟分离和方法验证, 比较了不同方法的优缺点. 证明第三种策略是一种较为快速, 并且可以使各阶梯上组分都能得到较好分离的优化方法.     

模拟退火神经网络用于药物液相色谱梯度分离条件的优化

模拟退火神经网络用于药物液相色谱梯度分离条件的优化。使用均匀设计法以乙腈在线性梯度展开时的初始浓度和线性梯度的斜率为优化参数,对六种药物混合体系进行优化。采用退火神经网络方法建立了有效的分离条件预测模型。对神经网络模型所预测的最佳分离条件进行试验,分离结果满意。模拟退火神经网络可有效地用于药物液相色谱分离条件的优化。     

人参皂甙的反相高效液相色谱多台阶梯度优化方法

建立了一种反相高效液相色谱多台阶梯度分离人参皂甙的方法.该方法以乙腈-水溶液为流动相,通过一系列等度实验,获得了8种人参皂甙Rg1,Re,Rf,Rg2,Rb1,Rc,Rb2和Rd的色谱保留参数,发现两参数保留方程不适合用于人参皂甙这种天然产物的分离条件的优化,而三参数保留方程的高精度才可满足预测的要求.在三参数保留方程的基础上,通过计算确定了8种人参皂甙(包括3台阶梯度)的液相色谱分离条件.通过实验对此优化条件进行了验证,实验结果显示了较好的预测精度和分离度.将本方法用于分离人参皂甙,分析时间短且分离度高,显示了等度台阶梯度优化方法对确定色谱分离条件的优越性.     

应用扩展的重叠分辨率法优化液相色谱条件分离二茂铁类化合物

本文对优化液相色谱分离条件的重叠分辨率法进行了改进与扩展：首先利用全范围的二元线性梯度淋洗进行溶剂强度的优化，再通过重叠分辨率法进行了溶剂选择性的优化，并且建立了计算机系统，使此方法程序化。利用此方法建立了分离Ｎ－二茂铁甲酰基－Ｎ＇－芳基硫脲类衍生物的最佳流动相体系。     

梯度洗脱优化-离子色谱-脉冲安培法分析婴幼儿配方乳粉中的糖和糖醇

建立了梯度洗脱优化-离子色谱-脉冲安培检测技术分析婴幼儿配方乳粉中麦芽糖醇、半乳糖、葡萄糖、蔗糖、果糖、乳糖6种与代谢疾病紧密相关的糖和糖醇的方法。该方法对样品的前处理、色谱柱的选择、淋洗液的梯度等色谱条件进行了优化,重点研究了淋洗液梯度对各组分分离效果的影响。将梯度洗脱程序分解为弱保留组分分离、乳糖分离、基质消除、系统平衡4个子程序,并分别对其进行了条件优化,实现了6种组分的完全分离,并有效解决了弱保留组分色谱峰易重叠、乳糖色谱峰易拖尾等现象。6种组分的线性范围为0.5~100 mg/L,相关系数（r）>0.99,方法的检出限（S/N=3）为0.06~0.40 mg/L。该方法具有分离度好、灵敏度高等优点,可满足例行分析的要求,同时也为淋洗液的梯度优化提供了可借鉴的方法。     

脑蛋白水解物中氨基酸的柱前衍生高效液相色谱测定

通过升高色谱柱温度,结合线性梯度洗脱的分离模式调整色谱分离的选择性,提出了一种测定脑蛋白水解物注射液中氨基酸含量的2,4-二硝基氟苯(DNFB)柱前衍生高效液相色谱方法。本法采用Kromasil C18(250×4.6 mm i.d.,5μm)色谱柱,柱温44℃,在30 min内以3个线性梯度能完全分离17种氨基酸,定量线性范围为0.2~1.0mg/L;加标回收率为89%~108%。该法具有适用性好、稳定性高等特点,也可以应用于其它种类样品中氨基酸的测定。     

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.