煤的超临界醇萃取脱硫：Ⅱ.碱处理及溶剂组成的影响

在半连续和间歇式反应器中考察了不同的碱处理方式和溶剂组成对煤脱硫的影响。半连续实验结果表明，用浸泡法处理煤样时随碱浓度的增加，脱硫率增加，但当碱浓度大于１０％，浸泡时间超过３０ｍｉｎ后，脱硫率又下降。用醇碱液作为萃取溶剂可明显地提高脱硫率，最高为５９．６％。改变溶剂组成并不能显著地影响脱硫率，当甲醇／水＝１∶１（摩尔）时，有机硫的脱除率最大（３２．９％。间歇釜实验结果证实，当碱／煤比大于０．５后，     

反相胶束增稳荧光法测定兔血浆中痕量盐酸水檗碱的研究

本文研究了气溶胶（ＡＯＴ）／环已烷／水反相胶束介质中中草药有效成分盐酸小檗碱的荧光性质，并将该法应用于兔血浆中痕量盐酸小壁碱的测定。该法的线性范围为１．０×１０－７～３×１０＾－５（ｇ／ｍｌ），检出限为８．３×１０＾－８（ｇ／ｍｌ），相对标准偏差为１．１％。     

高效毛细管电泳测定黄连及成药中小檗碱型生物碱的含量

报道了黄连及成药中七种小檗碱型生物碱的高效毛细管电泳分离测定方法。缓冲液由６５％磷酸氢二钠（用磷酸调ｐＨ７．０）和１５％甲醇组成。方法具有良好的精密度、回收率及线性关系。并用此法定量测定了黄连及六种成药中三种生物碱（小檗碱、巴马汀、药根碱）的含量。     

温和条件下煤化学净化的研究

添加助剂，用碱／酸两步处理（４￣６ｍｏｌ ＮａＯＨ，１ｍｏｌ ＨＣｌ，助剂浓度１￣２％Ｗ），在常压，１００℃左右时，对四种煤（大同、神木、平朔、太西）进行了脱矿物质的研究。最佳条件下可得到Ａｄ为０．３４％的超净煤。矿物质脱除率分别可达８１．８９％、８８．９６％、８８．５７％、７６．３５％。本文重点考察了助剂种类和浓度、碱浓度、反应时间等过程参数对ＹＡ的影响。并采用Ｘ射线衍射、红外光谱和电镜分析等手     

碱改性γ－Al_2O_3催化剂表面碱强度分布与COS水解活性的研究

用非水滴定法和Ｈａｍｍｅｔｔ系列指示剂测定了ＣＯＳ水解碱改性γ－Ａｌ_２Ｏ_３催化剂的表面碱强度分布．发现表面碱强度分布不均匀与表面能量分布不均匀相呼应．采用零点酸碱强度（Ｈ_（０，ｍａｘ））及碱中心区域分析法，Ｂｒｏｎｓｔｅｄ催化定律，进一步证实ＣＯＳ水解反应具有明显碱催化特征，较高活性催化剂的Ｈ_（０，ｍａｘ）一般为１０左右，对ＣＯＳ水解反应起主要作用的碱性中心的碱强度（Ｈ_０）为４．８≤Ｈ_０≤９．８．对碱金属氧化物改性后的γ－Ａｌ_２Ｏ_３催化剂，Ｂｒｏｎｓｔｅｄ规律在每个碱强度分区域内是适用的．     

高效液相色谱法测定血浆中莲心碱的浓度

采用高效液相色谱法（甲基莲心碱为内标）测定了血浆中莲心碱的浓度。以ＵｌｔｒａｓｐｈｅｒｅＳｉ为固定相、二氯甲烷－异丙醇－二乙胺（７５１５０．２,Ｖ／Ｖ）为流动相,检测波长为２８２ｎｍ。血样用氨－氯化铵缓冲液调ｐＨ１０后用乙醚提取。平均回收率９３．６％,ＲＳＤ为１．９％,最低检测浓度０．０２５ｍｇ／Ｌ。     

高效毛细管电泳法测定中草药川乌、草乌中乌头碱的含量

建立了测定有毒中草药川乌和草乌中３种乌头碱的高效毛细管电泳方法,系统地考察了电泳条件对分离的影响,并应用于香港市售川乌及草乌中中乌头碱、次乌头碱和乌头碱的测定。检测限为１．６７～２．３１ｍｇ／Ｌ,回收率为９３．０％～１０４．０％,相对标准偏差为０．６８％～１．７０％。     

高效毛细管电泳地测定中草药川乌,草乌中乌头碱的含量

建立了测定有毒中草药川乌和草乌中３种乌头碱的高效毛细管电泳方法,系统地考察了电泳条件对分离的影响,并应用于香港市售川乌及草乌中中乌头碱、次乌头碱和乌头碱的测定,检测限为１．６７－２．３１ｍｇ／Ｌ,回收率为９３．０－１０４．０％,相对标准差为０．６８－１．７０％。     

反相胶束增稳荧光法测定兔血浆中痕量盐酸小檗碱的研究

本文研究了气溶胶（ＡＯＴ）／环己烷／水反相胶束介质中中草药有效成分盐酸小檗碱的荧光性质,并将该法应用于兔血浆中痕量盐酸小檗碱的测定。该法的线性范围为１．０×１０－ ７～３×１０－ ５（ｇ／ｍ Ｌ）,检出限为８．３×１０－ ８（ｇ／ｍ Ｌ）,相对标准偏差为１．１％ 。     

液相色谱法测定槟榔饮片中槟榔碱含量的不确定度评定

根据《测量不确定度评定与表示》对液相色谱法测定槟榔饮片中槟榔碱含量的不确定度进行评定。通过分析得出,体积类不确定度是主要影响因素。分析结果表明,当槟榔饮片中槟榔碱含量为0．58％时,其扩展不确定度为0．02％（k=2）     

Lewis base catalyzed Mannich-type reactions between trimethylsilyl enol ethers and aldimines

Lewis base catalyzed Mannich-type reaction between trimethylsilyl enol ethers and N-tosylaldimines is described. Nitrogen anions generated from amides or imides such as lithium benzamide or potassium phthalimide are found to be effective Lewis base catalysts in DMF at room temperature to afford the corresponding beta-amino carbonyl compounds in good to high yields; the oxygen anion generated from carboxylic acids such as lithium acetate was also found to be effective in dry DMF. The above-mentioned lithium acetate-catalyzed Mannich-type reaction between aldimines and various trimethylsilyl (TMS) enol ethers such as silyl ketene acetal proceeded smoothly even in water-containing DMF. Then, Lewis base catalyzed three-component Mannich-type reactions of TMS enol ether, tosylamide, and aromatic aldehyde having electron-withdrawing group such as p-nitrobenzaldehyde were investigated. The reaction proceeded smoothly to afford the corresponding beta-amino ester in good yield. Further, ammonium carboxylates such as tetrabutyl ammonium acetate or tetrabutyl ammonium benzoate were found to be more effective Lewis base catalysts in the above-mentioned Mannich-type reaction. The synthesis proceeded in various solvents at lower temperatures. The reaction between aldimines and TMS enol ethers generated from thioester and various ketones such as propiophenone or cyclohexanone also proceeded smoothly to afford the corresponding beta-amino carbonyl compounds in high yields with good to high anti-selectivities.     

Systematic approach to extended even-tempered orbital bases for atomic and molecular calculations

Explicit formulas are established for simply generating arbitrarily large basis sets of optimal even-tempered Gaussian primitives which systematically approach complete bases for the entire function space. These bases, moreover, reproduce the corresponding optimal atomic SCF wavefunctions extremely closely and permit an extrapolation of the SCF energies to the Hartree-Fock limit. On the basis of the detailed quantitative information available from these calculations a simple general procedure is formulated for generating optimal even-tempered basis sets for molecular calculations.Dedicated to Professor Dr. Hermann Hartmann on the occasion of his 65th birthday.     

核酸水解产物嘌呤、嘧啶碱基在BDS柱上的分离及测定

 用高效液相色谱法测定了核酸水解的中间产物及最终产物 6种嘌呤、嘧啶碱基 ,探讨了色谱柱、流动相等对其分离的影响 ,确定了最佳色谱条件为 :HypersilBDS C18柱 ,乙腈 0 1mol/LKH2 PO4 (H3 PO4 调节 pH至4 0 5 ) (体积比为 2∶98)作流动相 ,紫外检测器在 2 6 0nm波长下检测。方法的精密度在 3%以内 ,回收率在 82 %～ 114%。方法应用于酵母核酸样品的测定中 ,取得了很好的结果。     

碱在过渡金属催化的有机化学反应中的作用

碱, 包括无机碱和有机碱, 在过渡金属催化的有机反应中发挥着重要作用. 本文概括地介绍和讨论相关文献中碱的作用机制. 碱的作用与许多因素有关, 包括: 碱性、溶解度、电离度、溶剂、聚集度、金属离子大小、金属离子Lewis酸性、金属离子的“软硬”度、阴离子的大小、阴离子的配位作用等. 碱可用于攫取质子、中和反应体系中的酸、活化催化剂、促进催化剂再生等, 碱中金属阳离子的作用主要集中在其对碱在有机溶剂中溶解度的影响和其与底物或溶剂间相互作用力的强弱上, 碱中阴离子的作用主要表现在离子与金属的配位方式和稳定性上; 有机碱和无机碱的主要区别体现在溶解度和空间位阻的不同上. 另外, 商品碱中极少量的过渡金属杂质也有可能对反应产生影响.     

Crystal and molecular structure of 5-trifluorothymine, a metabolite from human urine: Role of fluorine in stacking and hydrogen bonded interactions

The crystal structure of the metabolite from urine, 5-trifluorothymine [5F₃T] has been determined by single crystal X-ray diffractometric methods. Crystals of 5F₃T are monoclinic, space group P2₁/c with cell dimensions a = 6.7468(2), b = 15.0740(6), c = 13.4405(6), β = 90.412(2), V = 1366.88(8), Z = 8 (two molecules per asymmetric unit). Crystal structure of 5F₃T was determined with 3039 independent data and refined by full-matrix least squares methods to a final reliability factor of 0.047. Molecules of 5F₃T are connected by dimeric type of NH?O hydrogen bonding linking molecules related by a center of inversion into an extensive layer of dimeric molecules. These layers are stacked on top of each other at a stacking distance of 3.280 Å with a head-to-head stacking of the fluorine atoms on top of each other with no hydrogen bonding involving the fluorine atoms.     

Simultaneous separation of hydrophobic and polar bases using a silica hydride stationary phase

In this study, the retention behavior of selected hydrophobic and polar bases on a minimally modified silica hydride phase was investigated. From these results and the associated retention plots, significant differences in the chromatographic dependencies of these two classes of basic compounds were evident. The polar bases exhibited strong retention with mobile phases of high organic solvent content, but displayed weak retention with mobile phases of high water content. In contrast, the hydrophobic bases showed “U‐shape” retention dependencies, indicative of the interplay of both RP and normal‐phase retention characteristics. These studies have demonstrated that hydrophobic and polar bases can be simultaneously separated on the same column either under typical RP‐like or aqueous normal‐phase‐like conditions, respectively, with distinctive selectivity. Finally, the effects of temperature on the RP and aqueous normal phase modality of separations with these analytes were investigated, where discrete changes in retention behavior were also observed.     

Characterizing some gossypol and gossypolone Schiff's bases by studying their fragmentation patterns with electrospray ionization tandem mass spectra

To investigate the structural form of gossypol and gossypolone Schiff's bases,seven relevant Schiff's bases were synthesized and the electrospray ionization-tandem mass spectrometry(ESI-MS/MS) with low-energy collision-induced dissociation was used to analyze their fragmentations.A common fragmentation pathway with the loss of RNH_2 from those schiff's bases quasi-molecular ions was observed and proposed on the basis of their MS/MS spectra data.This common pathway indicated that those Schiff's bases exis...     

金属催化有机反应中的碱效应

众所周知, 在有机催化反应中经常用到不同的有机或无机碱, 许多碱本身也可以作为催化剂, 但化学家们对碱在化学转化中的作用并没有系统和明确的认识, 许多反应中碱的选择都是经过大量的条件实验确定的. 针对这些问题, 席振峰课题组对文献中碱的作用进行了系统归纳和总结, 分析了碱的多种因素对反应的影响并提出了一些规律性的结论, 对理解碱效应具有很高的参考价值.     

Synthesis,structure and characterization of some Schiff bases bearing phenylferrocene

Some novel Schiff bases bearing phenylferrocene were synthesized by condensation reaction of 4‐ferrocenylaniline with different aromatic aldehydes. The compounds prepared were characterized by spectroscopic methods (IR, UV–visible, ¹H and ¹³C NMR) and elemental analysis. The single crystal analysis of compound F1 [monoclinic, space group, P2₁/c (no. 14), a = 19.858(2), b = 7.416(2), c = 12.095(5) Å, β = 106.257(14) ] indicates a trans imine bond with a bond length of 1.270(2) Å, typical of a carbon‐nitrogen double bond. Copyright © 2007 John Wiley & Sons, Ltd.