气相色谱固定液极性和选择性评价

对非同族化合物溶质在两种固定相上保留值的关系进行了理论推导，并将该方程应用于８９种常见固定相的极性和选择性的评价。固定相的极性可用Ｂ值来评价，而选择性则用Ｂ、Ｔ３＾ａ，Ｃ３β值来评价。用该方程评价固定相具有两个优点，一是基于分子间作用力来评价固定相；二是探针化合物的选择不再受限制。     

一种新型极性脲丙基-C30固定相的制备和性能评价

以3-脲丙基三甲氧基硅烷为偶联剂，制备了一种新型极性脲丙基-C30（TPU-C30）反相色谱固定相。采用扫描电子显微镜、元素分析、红外光谱和热分析等对该固定相进行表征。结果表明，TPU-C30固定相已成功制备，连续制备3次固定相，其元素含量的相对偏差均小于5%，说明该合成工艺重复性良好。以不同极性、位置异构、碱性化合物为溶质探针，以传统的C18色谱柱与C30色谱柱为参比，对制备的固定相的色谱性能进行了研究。研究结果表明，TPU-C30固定相具有不同于传统C18柱、C30柱的选择性和更优的择形性，明显改善了碱性物质的峰形，其具有广阔的应用空间。     

烃类化合物在不同色谱柱上的定量结构-保留相关性研究

运用量子化学中的AMI方法计算烃类化合物的分子结构描述参数,借助逐步回归法建立了烃类化合物在不同极性色谱柱上的QSRR模型。结果表明：烷烃、烯烃、二烯烃类化合物在不同极性的色谱柱上的色谱保留与其分子结构描述参数之间具有较好的线性关系,烃类化合物在不同极性固定相上的保留主要与溶质分子的MR有关,即与溶质分子的色散力有关。随着溶质分子的不饱和度的增加,或固定相极性的增强,溶质分子与固定相之间的电荷传递作用随之增强。而且,烃类化合物在不同极性固定相上的色谱保留的QSRR模型均可用量化参数HOMO、LUMO、EICE以及MR参数来描述。所建立的在不同极性色谱柱上的烃类化合物的色谱保留QSRR模型预测烃类化合物的色谱保留值时具有较好的稳定性和准确性。     

线性非理想条件下液相色谱柱末端峰形规律

色谱流出曲线的二阶中心矩μ２和三阶中心矩μ３以及描述峰形非对称程度的偏态系数∑ｋ＝μ３／μ１．５２是反映色谱峰形的重要参数。从液相色谱过程动力学方程出发，运用电子计算机证明了在线性非理想条件下高效液相色谱体系中不同保留值组分在柱末端峰形的分布基本一致的结论。     

线性非理想条件下液相色谱柱末端峰形规律

 色谱流出曲线的二阶中心矩μ２和三阶中心矩μ３以及描述峰形非对称程度的偏态系数∑ｋ＝μ３／μ１．５２是反映色谱峰形的重要参数。从液相色谱过程动力学方程出发，运用电子计算机证明了在线性非理想条件下高效液相色谱体系中不同保留值组分在柱末端峰形的分布基本一致的结论。     

氮杂冠醚聚硅氧烷固定液的色谱保留机理

氨杂冠醚聚硅氧烷是一类呈中等极性的新颖气相色谱固定液．本文通过测定醇、酯、卤代烃和苯系列化合物的色谱保留值和相应势力学参数，研究它对上述不同化合物的保留机理及其分子识别的热力学性质     

含极性基团的硅质高效液相色谱固定相

介绍了含极性基团硅质高效液相色谱固定相的研究进展，对反相固定相的合成、极性基团作用机理和色谱性质方面作了评述，对手性分离固定相和高效离子色谱固定相方面的进展也作了简单综述。     

聚硅氧烷涂敷的反相高效液相色谱固定相

用甲基乙烯基聚硅氧烷涂敷于硅烷化的微粒硅胶上，制备出一种新型的涂敷型反相高效液相色谱固定相。该固定相对极性、非极性和碱性化合物均有良好的分离能力，峰对称性好。对其恶性循环 了考察，连续使用三个月后，固定相的碳量和色谱性能仍保持不变。     

二氢麦角碱在极性嵌入反相色谱固定相上的分离行为

二氢麦角碱的4种组分具有不同的药效特性,需适当的分析方法对其在不同剂型药品中的含量进行分析.传统液相色谱方法使用强碱性流动相,严重腐蚀硅胶基质色谱填料,影响色谱柱寿命.合成了极性嵌入反相固定相--C18酰胺固定相,并在中性流动相条件下分离4种组分.考察了流动相组成和pH对二氢麦角碱在C18酰胺固定相上保留行为的影响.在150 mm×4.6 mm I.D.的C18酰胺色谱柱上,流动相为乙腈-20 mmol/L Na2HPO4(30:70,V/V,pH 7.0)的条件下实现了4种组分的基线分离.与传统方法相比,极性嵌入反相固定相可以有效的改善碱性化合物的分离特性和大幅度地延长色谱柱的使用寿命.     

液相色谱中一个新的表征参数Z：Ⅱ.反相液相色谱中小分子极性溶质体系

反相高效液相色谱（ＲＰＬＣ）中小分子极性溶质的极性是可以用液相色谱中溶质计量置换保留模型中的Ｚ值（１ｍｏｌ溶质被固定相吸附时，在固定相与溶质子间释放出置换剂的ｍｏｌ数）来表征的，其大小可用带有该极性端基的同系物的Ｚ值对碳原子数线性作图的截距求得。这些检性基的Ｚ测量定值与疏水性片段指数１ｇｆ间有极好的线性关系。依此关系还可测出一些用其他实验方法无法测得的某些基团的１ｇｆ值。     

THE REACTION OF METHYLENE WITH HYDROGEN

Abstract— An investigation has been made of the reaction between methylene, formed by the photolysis of ketene, and hydrogen. Ethane, ethylene and methane are the major hydrocarbon products, and it has been shown that the formation of these products may be adequately described by the sequence of processes
CH₂CO + hv → CH₂+ CO (1)
CH₂+ H₂→ CH₃+H (2)
2CH₃→ C₂H₆ (3)
CH₃+ H₂+ CH₄+ H (4)
CH₂+ CH₂CO → C₂H₄+ CO (7)
In particular, the relative rates of ethane and methane formation are consistent with the known rate constants for reactions (3) and (4), and it is not therefore necessary to postulate the participation of an 'insertion' process
CH₂+ H₂→ CH₄ (6) to account for the formation of methane.
Decrease of the energy possessed by the methylene, either by increase of the wavelength of ketene photolysis, or by increase of gas pressure, is shown to result in an increase in the reactivity of the methylene towards ketene relative to its reactivity towards hydrogen (i.e. the ratio k₂/k₂ increases).     

STUDIES ON THE STEREOMECHANISM OF THE REACTION OF SULPHIDES WITH CHLORAMINE-T

Abstract

In the reactions of sulphides (RQS) with chlaramine-T (TsNClNa) sulphilimines (RQSNTs) and sulphoxides (RQSO) are known to be produced from a chlorosulphonium-sulphon-amidate ion-pair intermediate (RQSC1⁺, TsNH^?) in fast competitive S_N reactions of different steric controll. The stereomechanism was investigated in reactions of sulphides (RQ?S) with asymmetric carbon atom adjacent to sulphur, leading to diastereomeric sulphilimines (RQ?S?NTs) and sulphoxides (RQ?S?O). The proportions and the configurations of the diastereomers of both products were determined. The efficiency of the asymmetric induction was found to depend on the bulkiness of the substituents of sulphides. The major diastereomeric components of the produced sulphilimines and sulphoxides proved to have opposite configurations about sulphur. On this basis, the hydrolysis of chlorosulphonium ion yielding sulphoxide is assumed to proceed through a sulphurane intermediate via an a-a type ligand exchange, while the formation of sulphilimine from chlorosulphonium -sulphonamidate ion-pair may involve an a-e type displacement.     

THIATION OF CARBONYL COMPOUNDS WITH THE DIMER OF P-METHOXY-P-THIONOPHOSPHINSULFIDE

Abstract

Recent studies on thiation of carbonyl compounds with organic P,S-compounds have shown that p-methoxyphenyl-thionophosphinsulfide (1) is the most effective thiation reagent for ketones, carboxamides, esters, and thioloesters hitherto known.     

THE COPOLYMERIZATION OF 1-ALKYLVINAZENES WITH STYRENE

Copolymers are formed between styrene and 1-alkyl-4,5-dicyano-2-vinylimidazoles (1-alkylvinazenes). The reactivity ratios for the 1-ethylvinazenes are determined to be high, but also appear to vary with feed composition, with low feed ratios of 1-ethylvinazene giving r_EtVz=35 ± 6 and r_Sty=0.077 ± 0.029, whereas at higher 1-ethylvinazene feed fractions, r_EtVz=2.5 ± 2 and r_Sty=0.089±0.021. Mediation of the 1-methylvinazene/styrene copolymerization with 2,2,6,6-tetramethylpiperidine-N-oxide (TEMPO) leads to a more controlled polymerization which moves closer to ideal copolymerization behavior. The copolymers form with polydispersities approaching 1.5, suggesting bimolecular termination kinetics. The copolymers comply with the Fox relation for T_g.     

植物血凝素与金属离子锰(Ⅱ)的配位作用

植物血凝素简称PHA是从菜豆中提取的一种凝集素,能激活T淋巴细胞使其增殖,含有红血球凝集素(H-PHA)和白血球凝集素(L-PHA),某些凝集素分子中含有金属离子,如Mn~(2+)、Ca~(2+)等,这些凝集素与糖结合的活力和生物活性均依赖于金属离子的存在,这表明金属离子对凝集素的活性有影响.PHA与金属离子的作用研究还未见报道,本     

THE IN VIVO ASSOCIATION OF MANGANESE WITH THE CHROMOSOME OF MICROCOCCUS RADIODURANS

Abstract —Extremely high levels of paramagnetic manganese (Mn²⁺) which quench phosphorescent reactions have been found to inhibit the formation of thymine-containing dimers in M. radiodurans . Lowering the concentration of Mn²⁺ in the culture medium resulted in a lower intracellular concentration of Mn²⁺, an increase in the UV-sensitivity of this bacterium, and a larger photochemical yield of thymine-containing dimers. High levels of paramagnetic Mn²⁺ were not found in other test organisms which are more sensitive to UV-irradiation. One interpretation of our data is that in Micrococcus radiodurans Mn²⁺ may bind to the chromosome and thereby reduce the photochemical yield of thymine-containing dimers.     

六次甲基四胺与氯化苄加合物的晶体结构

六次甲基四胺(HMT)与氯化苄加成所得的Sommelet反应中间产物的单晶样品用SYNTEX R3型四圆衍射仪,以θ/2θ扫描方式收集了2677个衍射数据并进行了结构分析.晶体属空间群P2₁2₁2₁.晶胞参数α=7.692(1)Å,b=18.405(3)Å,c=19.059(3)Å,晶胞中含八个G₆H₅CH₂Cl·N₄(CH₂)₆.经PL,K,B及吸收因子的校正得绝对强度.全部非氢原子坐标的初始参数由SHELXTL直接法程序所得的E图导出.对坐标及热参数经六轮块矩阵最小二乘法修正,再加入氢原子修正两轮后得一致性因子R₁=0.040,R₂=0.032(加权).结构分析证实,此Sommelet反应中间物由季胺盐阳离子与氯离子所组成.在晶体中观察到苄基与HMT中N^*直接键连,并导致HMT中N^*—C^*键有极显著的键长增长效应,而与N^*—C^*邻接的C^*—N键则有所增强.由此预期当此加合物水解时,N^*—C^*弱键首先瓦解是较合理的.     

甲基丙烯酸甲酯在环烷酸钕—三异丁基铝α,α‘—联吡啶催化体系中聚？…

自６０年代以来,Ｚｉｅｇｌｅｒ型催化剂用于极性单体甲基丙烯酸甲酯（ＭＭＡ）的聚合研究较多,如由钛、矾、铁等过渡金属化合物与烷基铝组成的催化剂［１～３］．近年来出现了锆、稀土配位催化聚合ＭＭＡ及其他丙烯酸酯的报道［４～６］,这些催化剂引发ＭＭＡ聚合机理相当复杂,有的为自由基型,有的则为配位阴离子型．本文报道极性单体ＭＭＡ在环烷酸钕三异丁基铝α,α’联吡啶体系中的聚合特征和聚合反应动力学,并初步探讨了反应机理．１　原料及试剂甲基丙烯酸甲酯为化学纯,按常法纯制．苯、甲苯、四氢呋喃、石油醚、环己烷…