共查询到20条相似文献,搜索用时 93 毫秒
1.
洋葱状富勒烯的表面化学修饰 总被引:6,自引:0,他引:6
采用稀硝酸对洋葱状富勒稀(OLFs)进行了纯化处理, 用HRTEM观察了OLFs纯化前后的形态与结构, 用TGA技术定量分析了OLFs的纯化效果, 然后使OLFs与金属钾在甲苯中回流, 并采用FTIR光谱和Raman光谱对反应前后的OLFs进行了光学性能表征. 红外光谱在3451, 1402和1039 cm-1处出现了羟基的特征峰, 表明形成了OLFs羟基化合物; Raman光谱中IG/ID的比值增大, 说明OLFs的石墨化程度提高, 反应前后G峰和D峰的位置无明显区别, 表明OLFs的整体结构未发生变化. 相似文献
2.
反相液相色谱对多肽的分离、纯化与制备 总被引:19,自引:2,他引:17
用反相高效液相色谱(RPLC)对两种化学合成多肽--32肽和21肽进行了分离、纯化和制备。在用分析型RPLC色谱柱对多肽样品的制备过程中,对其进样量和洗脱梯度进行了选择。每次进样量为5mg,在最优化色谱条件下,用RPLC一步就可对21肽进行分离纯化,其纯度达到98.6%。而32肽由于样品组分更加复杂,RPLC一步纯化后其纯度仅有80%。通过对色谱分离条件的再次优化,对32肽进行二次分离纯化,纯度达杂,RPLC一步纯化后其纯度仅有80%。通过对色谱分离条件的再次优化,对32肽进行二次分离纯化,纯度达到96.4%。在其最优化条件下,通过多次样品收集和冷冻干燥,分别制备了高纯度的21肽和32肽各100mg。 相似文献
3.
研究了蛋白质纯化制备的二种运行模式,其一,在色谱柱超载下纯化制备蛋白质模式,并成功地用离子交换色谱纯化制备了大豆中的胰蛋白酶,用反相液相色谱纯化了细胞色素C;其二,用溶质-溶质顶替色谱纯化制备了核糖核酸酶-A,并对顶替色谱过程中诸参数进行了讨论和选择。 相似文献
4.
5.
以甲硫醇钠为原料,通过与稀硫酸反应制备甲硫醇。对甲硫醇和甲烷分别进行纯化,采用气相色谱-火焰光度检测器与气相色谱法氦离子放电检测器对纯化后的甲硫醇和甲烷进行纯度分析,甲硫醇纯度(摩尔分数)为99.75%,甲烷纯度(摩尔分数)为99.997%。通过称量法制备了甲烷中甲硫醇气体标准物质。采用气相色谱法火焰光度检测器对标准物质进行了均匀性检验、稳定性考察。研制的甲烷中甲硫醇标准物质标称浓度为100μmol/mol,F检验和回归曲线法实验结果表明,在压力0.5~10 MPa范围内,该标准物质具有良好的均匀性和稳定性,定值结果的相对扩展不确定度为2%(k=2),有效期为12个月。 相似文献
6.
纯化对三元无皂共聚胶粒性质的影响 总被引:1,自引:0,他引:1
以离子交换和高速离心两方法纯化含不同功能基的三元无皂共聚胶乳,用TEM和电导滴定检测比较了以上两方法的纯化效果,同时考察了这两种纯化方法对三元无皂胶粒形态,大小及表面功能其量的影响。研究发现,只有通过多次离心-倾析-再分散过程才能将胶乳所有杂质除去。离子交换和离心纯化不影响胶粒形态大小,而离心纯化使粒表面功能其量发生显著变化。 相似文献
7.
肝素亲和层析是利用生物大分子与层析介质表面的肝素特异性结合而进行选择性分离的一种技术,使用条件温和,纯化过程中能较好保持目标蛋白的生物活性。本文在阐述肝素与层析介质化学反应机理的基础上,系统论述了溴化氰活化及偶联法、环氧活化及偶联法、席夫碱法和碳二亚胺缩合法四种肝素亲和层析介质制备方法,深入分析了各制备方法的优缺点,总结了肝素亲和层析在血液制品、病毒纯化方面的应用。最后,进一步分析了肝素亲和层析在蛋白分离纯化领域应用存在的问题,并展望了其未来发展趋势,以期为肝素亲和层析介质的制备方法提供新思路。 相似文献
8.
蔗糖酯的合成研究进展 总被引:2,自引:0,他引:2
综述了蔗糖酯的合成方法及工艺的研究进展,并对其反应机理进行了阐述.蔗糖酯的合成方法主要有四种:溶剂法、微乳化法、无溶剂法以及酶催化法.溶剂法采用DMF或DMSO为溶剂,但是这两种溶剂均有毒,限制了蔗糖酯在食品等行业的应用.微乳化法采用丙二醇或水代替溶剂法所使用的有毒溶剂,并加入乳化剂,使反应体系近似为均相体系.无溶剂法则是通过在反应体系中加入乳化剂或表面活性剂等使熔融相成均一相,反应平稳.但是一般无溶剂法反应温度较高,反应不易进行,产率低,且产品质量得不到保证.酶催化合成法是一种新的生物合成方法,采用生物酶代替传统的催化剂合成蔗糖酯,该法催化活性高、反应条件温和、选择性强、产物易分离等优点.文中还对蔗糖酯粗品的纯化工艺进行了介绍. 相似文献
9.
10.
11.
Maaroof Zarei 《Tetrahedron》2017,73(14):1867-1872
A simple and efficient synthetic method for the one-pot synthesis of 1,3,4-thiadiazoles utilizing Vilsmeier reagent was developed. In this method carboxylic acids and hydrazine were converted to 1,3,4-thiadiazoles in the presence of Vilsmeier reagent and Lawesson's reagent. The influence of the thionation reagent, solvent, temperature and time, in this reaction was discussed. The developed methodology for 1,3,4-thiadiazole synthesis has the advantage of simplicity, ambient reaction conditions, easy purification and good to excellent yield of products. 相似文献
12.
4-氨基-5-烃基-2,4-二氢-3H-1,2,4-三唑-3-硫酮席夫碱的简便合成 总被引:10,自引:1,他引:9
近年来,人们发现标题类杂环席夫碱能发生很多新颖的反应,且其中许多具有强的生物活性[1~7].但其制备多以乙醇为反应介质,以酸或碱为催化剂,反应需经数小时,后处理也比较麻烦.本文报道了题示席夫碱的一种极为简便的合成方法,反应介质选用低级的脂肪酸(如冰醋... 相似文献
13.
加速溶剂萃取-凝胶色谱净化-气质联用测定土壤中15种有机氯农药残留的方法研究 总被引:4,自引:1,他引:3
建立了加速溶剂萃取-凝胶色谱净化-气质联用同时测定土壤中15种有机氯农药的分析方法。优化了凝胶色谱(GPC)净化的条件,比较了凝胶色谱净化及浓硫酸净化法对15种有机氯回收率的影响。结果表明,采用GPC净化能够有效避免浓硫酸净化对氯丹、异狄氏剂、硫丹、甲氧滴滴涕等农药回收率的影响,GPC净化的最佳收集时间为10~15 min,15种有机氯农药的回收率为56%~122%。15种有机氯农药在0.03~6.0 mg/L范围内具有较好的线性,相关系数达0.999以上,方法的检出限为0.1~5.0μg/kg,定量下限为0.4~16.0μg/kg。采用该方法对实际样品进行加标回收率实验,土壤样品的加标回收率为68%~122%,相对标准偏差为1.2%~5.9%。该方法简单、快捷、灵敏度高,已用于实际土壤样品的检测。 相似文献
14.
探索了一种适用于Pt/CNTs催化剂的纯化方法.利用比表面积测定、X射线衍射(XRD)、透射电子显微镜(TEM)和电化学等手段进行了表征.研究结果表明,经该方法纯化的CNTs作为载体制备的阳极催化剂表现出明显优于相应的混酸氧化法纯化的CNTs为载体的催化剂催化性能. 相似文献
15.
16.
Applications of counter-current chromatography in organic synthesis purification of heterocyclic derivatives of lapachol 总被引:1,自引:0,他引:1
Silva RS Leitão GG Brum TB Lobato AP Pinto Mdo C Pinto AV 《Journal of chromatography. A》2007,1151(1-2):197-202
This work describes the application of counter-current chromatography (CCC) as a useful, fast and economic alternative for the isolation and purification of heterocyclic derivatives from lapachol and beta-lapachone, two naturally occurring compounds from Tabebuia species, and nor-beta-lapachone, a synthetic congener of lapachol. The discussed data comprise four examples of purification of synthetic reactions with different solvent systems - the mixture of the oxazole and the imidazole from beta-lapachone; the quinoxaline from nor-beta-lapachone; and the purification of the N-oxides from the quinoxaline and the phenazine from nor-beta-lapachone from their respective not fully reacted substrates by means of aqueous reversed- and normal-phase elution modes and non-aqueous solvent systems. Traditional purification of these reaction products by silica gel column chromatography demanded a large amount of solvent and time and, in some cases, serious degradation of the products occurred, leading to low yield of the reaction. High-speed counter-current chromatography (HSCCC) was used as an alternative to optimize the process and raise the yield of the reactions. 相似文献
17.
Xiao Lu Zhiji Luo Ruili Huang Donald C. Lo Dr. Wenwei Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(50):e202201421
Detecting the formation of new chemical bonds in high-throughput synthesis is limited by the efficiency and scalability of reaction product detection, as conventional methods for isolating product from reaction mixtures are time consuming and labor intensive. Here, we report a miniaturizable purification method that enables the rapid, high-throughput isolation of quaternary ammonium-tagged products from reaction mixtures with excellent purity using inexpensive equipment that easily can be set up in a typical organic chemistry laboratory. This novel purification technique enabled us to establish a high-throughput reaction discovery platform. We validated this platform in a screen of 1536 reactions, and one previously unreported transformation was identified. 相似文献
18.
19.
20.
Nockemann P Thijs B Driesen K Janssen CR Van Hecke K Van Meervelt L Kossmann S Kirchner B Binnemans K 《The journal of physical chemistry. B》2007,111(19):5254-5263
Choline saccharinate and choline acesulfamate are two examples of hydrophilic ionic liquids, which can be prepared from easily available starting materials (choline chloride and a non-nutritive sweetener). The (eco)toxicity of these ionic liquids in aqueous solution is very low in comparison to other types of ionic liquids. A general method for the synthesis and purification of hydrophilic ionic liquids is presented. The method consists of a silver-free metathesis reaction, followed by purification of the ionic liquid by ion-exchange chromatography. The crystal structures show a marked difference in hydrogen bonding between the two ionic liquids, although the saccharinate and the acesulfamate anions show structural similarities. The optimized structures, the energetics, and the charge distribution of cation-anion pairs in the ionic liquids were studied by density functional theory (DFT) and second-order (M?ller-Plesset) perturbation theory calculations. The occupation of the non-Lewis orbitals was considered to obtain a qualitative picture of the Lewis structures. The calculated interaction energies and the dipole moments for the ion pairs in the gas phase were discussed. 相似文献