共查询到18条相似文献,搜索用时 70 毫秒
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对磺酸基苯基亚甲基若丹宁光度法测定三乙酸甘油酯中的汞 总被引:1,自引:0,他引:1
合成了一种新的若丹宁类试剂对磺酸基苯基亚甲基若丹宁 (SBDR) ,并用红外光谱和元素分析进行结构鉴定。研究了该试剂与汞的显色反应 ,在 p H4.0的HAc- Na Ac缓冲介质中 ,吐温 - 80存在下 ,SBDR与汞反应生成 2∶ 1稳定络合物 ,λmax=5 1 0 nm,ε=1 .0 7× 1 0 5L· mol- 1· cm- 1。汞含量在 0~ 3 0μg/2 5 m L内符合比耳定律。方法用于三乙酸甘油酯中汞含量的测定 ,结果满意。 相似文献
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制备了用于快速检测三油酸甘油酯的脂肪酶修饰丝网印刷电极(SPE)电化学传感器单元。用循环伏安法(CV)和计时电流法(CC)研究了三油酸甘油酯在脂肪酶修饰SPE上的电化学行为,确定了测定甘油酯的最优条件,建立了测定三油酸甘油酯浓度的电化学方法。其中CV法的线性范围为0.01~5 g.L-1,检出限为2.5 mg.L-1;CC法的线性范围为0.001~5.50 g.L-1,检出限为0.2 mg.L-1。以CV法考察样品的加标回收率,6个葵花籽油样品的加标回收率为94%~105%。 相似文献
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磺酸功能化的MCM-41催化三乙酸甘油酯与甲醇的酯交换反应 总被引:2,自引:0,他引:2
通过在孔壁上覆盖糠醇聚合物,于不同温度下用浓硫酸直接进行磺化制备了一系列磺酸基功能化的MCM-41介孔材料,并用氮气吸附-脱附、XRD、XPS和红外光谱等方法对其进行了结构表征,以三乙酸甘油酯和甲醇的酯交换反应为模型反应研究了生物柴油的制备.结果表明,在介孔结构完好的情况下,一定数量的磺酸基嫁接到了MCM-41的孔擘上... 相似文献
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以N-(2-溴乙基)邻苯二甲酰亚胺或N-(4-溴丁基)邻苯二甲酰亚胺和硫氢化钠为起始原料,通过取代、肼解、亲核加成等反应合成了10个三芥子酸甘油酯(erucin)类似物,通过核磁共振氢谱、碳谱及质谱对其结构进行了确认。采用比浊法初步测试了其对大肠杆菌、金黄色葡萄球菌、白色葡萄球菌、藤黄八叠球菌、枯草芽孢杆菌、蜡状芽孢杆菌和四联球菌等7种菌的生长抑制活性,测试结果显示,化合物对测试菌种都表现出较好的生长抑制活性,其中苄硫乙基-1-硫代异硫氰酸酯(5e)和苄硫基丁基-1-硫代异硫氰酸酯(5j)活性最高,对大肠杆菌的最低生长抑制浓度仅为7.8μg/m L,对金黄色葡萄球菌的最低生长抑制浓度也仅为15.6μg/m L和31.2μg/m L。 相似文献
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新型温控离子液体介质中脂肪酶催化合成乙酸苯乙酯 总被引:1,自引:0,他引:1
设计合成了三种同分异构离子液体 1,3-二正戊基咪唑六氟磷酸盐 ([D(n-C5)Im]PF6)、1,3-二异戊基咪唑六氟磷酸盐 ([D(i-C5)Im]PF6) 和 1,3-二 (2-甲基丁基) 咪唑六氟磷酸盐 ([D(2-mb)Im]PF6). 以假单胞菌脂肪酶 Pseudomonas cepacial 催化合成乙酸苯乙酯为模型反应, 分别考察了反应介质对酶行为的影响. 结果发现, 酶在离子液体[D(2-mb)Im]PF6 中的活性及反应性能明显高于有机溶剂正己烷. 基于[D(2-mb)Im]PF6 离子液体的温控特点, 提出了一种高温反应与低温分离相结合的乙酸苯乙酯合成路线. 通过优化实验, 得到合成乙酸苯乙酯的最佳反应条件为: 30 mg 酶, 1.0 g 离子液体, 2% 含水量, 反应温度 35 oC, 反应时间 48 h. 此时, 乙酸苯乙酯产率达 92.3%. 脂肪酶在[D(2-mb)Im]PF6 中的稳定性是在正己烷中的 7.4 倍, 且重复使用 10 次后催化活性没有明显降低. 此外, 采用圆二色谱和内源荧光光谱法研究了不同介质中脂肪酶结构的变化. 结果表明, 脂肪酶在[D(2-mb)Im]PF6 中有较大的氨基酸残基裸露程度和良好的二级结构稳定性. 相似文献
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G. D. Gamalevich A. V. Ignatenko E. P. Serebryakov N. E. Voishvillo 《Russian Chemical Bulletin》1995,44(4):743-748
With a view to obtaining both enantiomers of 3-(4-methoxycarbonyl)phenyl-2-methyl-1-propanols, (R)-1 and (S)-1, from the respective racemate, (±)-1, the hydrolysis of its acetate, (±)-2, in the presence of porcine pancreatic lipase (PPL) has been studied. The optical puriry of (R)-1 and (S)-1 thus obtained was unsatisfactory (ee 22–27%), and could not be increased beyondee 33% by repeated enzymatic hydrolysis of the unconverted fraction of the acetate. In contrast with this, the biohydrogenation of 3-(4-methoxycarbonyl)phenyl-2-methyl-2-propen-1-ol (4) with fermentingSaccharomyces cerevisiae afforded (S)-1 of considerably higher optical purity (ee 41–90 %, depending on the strain). The stereochemical correlation of the products obtained in the two biochemical processes under study shows that the PPL-catalyzed hydrolysis of (±)-2 produces preferably (R)-1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 761–766, April, 1995.The authors express their gratitude to the Russian Foundation for Basic Research for financial support (Grant No. 93-03-5893). 相似文献
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Jian Feng GE Li Fen ZHANG Zong Xuan SHEN Ya Wen ZHANG* Department of Chemistry Chemical Engineering Suzhou University Suzhou Department of Material Engineering Suzhou University Suzhou 《中国化学快报》2001,(7)
Mercaptoalcohols are a rare class of natural products. Some optically active mercaptoalcohols have been used as catalysts in asymmetric reduction of prochiral Ketone1,2. In this letter, we report the synthesis of a new optically active (-mercaptoalcohols, (R)-1,1-diphenyl-2-mercapto-3-methyl-1-butanol 7, from L- valine.Our first attempt is showed in Scheme 1. According to literature's method L-valine was converted to (S)-2-Hydroxy-3-methylbutanoic acid 21,2. 2 was treated with MeOH/SOCl2… 相似文献
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Liisa Pikkarainen 《Journal of solution chemistry》1988,17(11):1093-1099
The excess molar enthalpies of binary solvent mixtures of 1-butanol and 2-methyl-2-propanol with aniline, N-methylaniline, and N,N-dimethylaniline were measured with a flow microcalorimeter at 40°C. The excess enthalpies are positive for all the systems, and smaller for the mixtures of 1-butanol than the corresponding mixtures of 2-methyl-2-propanol. With respect to the anilines, the values increase in the order aniline < N-methylaniline < N,N-dimethylaniline. 相似文献
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Alessandro D'Aprano Ines Dorina Donato Vincenzo Turco Liveri 《Journal of solution chemistry》1989,18(8):785-793
Static dielectric constants, refractive indices and viscosities of 1-pentanol +2-methyl-2-butanol mixtures were measured at 5, 25 and 45°C. The results show that the mixing of the two isomers modifies the polarizability and the resistence of viscous flow of the system depending on the composition and temperature. Short range intermolecular interactions producing hetero-alcohol open dimers are considered. 相似文献
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Partial molar volumes at infinite dilution, V02, of alkali–metal halides (LiCl, NaCl KCl RbCl CsCl, NaBr, KBr, KI), tetra-n-alkylammonium bromides, R4NBr (R=Me, Et, n-Pr, n-Bu, n-Pen), NaBPh4, and Ph4PCl have been determined in binary solvent mixtures of water with 2-methyl-2-butanol covering the water-rich region and the alcohol-rich region at 298.15 K. V02 for alkali–metal halides show relatively little dependence on the solvent composition. However, in the case of hydrophobic electrolytes the observed effects are more pronounced. A good linear dependence between V02(R4NBr) and the molecular weight of the tetra-n-alkylammonium cation is found. Limiting single-ion volumes have been obtained using the assumption that V0(Ph4P+)–V0(BPh–4)=2.0 cm3-mol–1. The trends in the single-ion volumes are discussed in both solvent regions. 相似文献
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An attempt was made to use a simple procedure to obtain D- and L-allothreonine (D- and L-aThr), which are non-proteinogenic alpha-amino acids and are useful as chiral reagents in asymmetric syntheses. DL-aThr that exists as a conglomerate was optically resolved by replacing crystallization with L-alanine (L-Ala) as an optically active co-solute. D-aThr was preferentially crystallized from an aqueous solution of DL-aThr in the presence of L.-Ala, as was L-aThr in the presence of D-Ala. Furthermore, a diasteroisomeric mixture of D-aThr and L-threonine (L-Thr) and one of L-aThr and D-Thr were prepared, respectively, by epimerization of L- and D-Thr using salicylaldehyde as the catalyst in acetic acid. Based on the result of the replacing crystallization, D- and L-aThr were separated from aqueous solutions of the diastereoisomeric mixtures in the presence of L- and D-Ala. The partially resolved D- and L-aThr were recrystallized from water to yield the corresponding enantiomers in optically pure forms. 相似文献