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1.
测定了一系列有机铵盐与一种全氟烷磺酸盐1:1混合体系水 溶液的表面张力,由此研究有机铵盐对碳氟表面活性剂表面活性及溶度的影响,导出应用于此种混合体系的Gibbs吸附公式,并讨论了混合体系中两表面活性组分的表面分子相互作用和表面层的结构。 相似文献
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双波长分光光度法测定混合组分 总被引:9,自引:3,他引:6
双波长分光光度法测定单组分,倘若以显色试剂吸收峰为参比波长,配合物吸收峰为测量波长(即双峰双波长法)可显著提高灵敏度,将该法用於混合组分体系的测定还未见报导。本文对双波长分光光度法测定混合干扰体系进行了研究,导出了双波长分光光度线性方程,对轻、重稀土-二甲酚橙-CTMAB体系及钴、镍-PAR体系进行了测定,采用直线回归及最小二乘两种方法处理实验数据。理论及实验均表明,采用此法测定混合组分体系,灵敏度较通常的单波长测定法有所提高。 相似文献
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两相体系分光光度法测定聚乙二醇化蛋白质混合物中游离聚乙二醇 总被引:3,自引:0,他引:3
建立了用硫氰酸铁胺-氯仿两相体系分光光度法测定游离聚乙二醇含量的方法。确定了最大吸收波长,考察了混合振荡时间、其他生物大分子存在对测定结果的影响,并与三硝基苯磺酸(TNBS法)进行了比较。 相似文献
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不同混合酸消解样品对电感耦合等离子体原子发射光谱法测定土壤中重金属含量的影响 总被引:6,自引:0,他引:6
为探究不同混合酸对电感耦合等离子体原子发射光谱法测定土壤中重金属元素(铜、锌、铅、镍和铬)的影响,对土壤进行多晶衍射分析,采用硝酸-高氯酸、盐酸-硝酸、盐酸-硝酸-氢氟酸-高氯酸、盐酸-硝酸-氢氟酸混合酸对4种不同类型土壤(黑钙土、褐土、棕壤、红壤)进行了分析。结果表明:该4种混合酸对标准样品的测定都具有较高的准确性与精确性;不同的混合酸的对不同类型土壤中重金属元素的测定具有一定的影响,其中对铬的影响最大;完全消解体系(盐酸-硝酸-氢氟酸-高氯酸、盐酸-硝酸-氢氟酸混合酸)的测定结果不同程度地高于不完全消解体系(硝酸-高氯酸、盐酸-硝酸混合酸)的结果。所以对于土壤重金属元素的测定,混合酸需要针对土壤类型,重金属元素种类等因素进行选择。 相似文献
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十二烷基季铵盐及其与十二烷基硫酸钠混合体系的表面活性 总被引:13,自引:0,他引:13
通过表面张力测定,研究了十二烷基季铵盐C12H25N(CnH2n+1)3Br(n=1,2,3,4)及其与十二烷基硫酸钠混合体系的表面活性,应用规则溶液理论,计算了混合体系表面吸附层和胶团的组成及分子相互作用参数,对于季铵盐、极性基影响大:cmc随n增加而下降,γcmc则先上升,后下降,自极性基碳链的空间阻碍、疏水、弯曲效应,以及电荷屏蔽效应可对此予以解释,对于混合体系,极性基大小对其表面活性及胶团 相似文献
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因子分析-紫外吸光光度法同时测定苯酚甲苯酚和间苯二酚 总被引:2,自引:0,他引:2
采用因子分析技术,用Visual Basic语言编辑分析程序,通过目标转换方式对苯酚、甲苯酚和间苯二酚严重重叠的紫外光谱数据进行处理,实现了三酚混合体系的同时测定.结果满意。 相似文献
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两次双波长分光光度法同时测定钴、镍、铜 总被引:1,自引:0,他引:1
本文用两次双波长分光光度法实现了三组分混合体系的同时测定。结果表明,两次双波长测量信号△A_1和△A_2的线性组合与混合体系中各组分浓度呈线性关系。该法用于钻、镍、铜三组分同时测定,定量结果令人满意。 相似文献
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提出了可应用于四元混合体系同时测定的比光谱-导数分光光度法,阐述了该方法的基本原理,并将其应用于氨基比林、苯巴比妥、咖啡因和非那西丁四元混合体系中各组分的同时测定。结果表明,氨基比林、笨巴比妥、咖啡因和非那西丁的回收率分别是109.3%(RSD=4.3%)、102.4%(RSD=6.6%)、108.7%(RSD=5.1%)、98.62%(RSD=3.2%)。方法的准确度和精密度都可以满足四组分同时测定的要求,方法简单、快速。 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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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. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
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. 相似文献
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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. 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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. 相似文献
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An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
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Mohammed KajjoutChristian Rolando 《Tetrahedron》2011,67(25):4731-4741
Quercetin, the polyphenolic compound, which has the highest daily intake, is well known for its protective effects against aging diseases and has received a lot of attention for this reason. Both quercetin 3-O-β-d-glucuronide and quercetin 3′-O-β-d-glucuronide are human metabolites, which, together with their regioisomers, are required for biological as well as physical chemistry studies. We present here a novel synthetic route based on the sequential and selective protections of the hydroxyl functions of quercetin allowing selective glycosylation, followed by TEMPO-mediated oxidation to the glucuronide. This methodology enabled us to synthesize the five O-β-d-glucosides and four O-β-d-glucuronides of quercetin, including the major human metabolite, quercetin 3-O-β-d-glucuronide. 相似文献