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《理化检验(化学分册)》2010,(6)
研究了显色剂二溴对甲偶氮二溴羧与钴(Ⅱ)的显色反应。在pH 10.2的柠檬酸铵-氨水缓冲溶液中,钴(Ⅱ)与二溴对甲偶氮二溴羧反应形成绿色配合物,最大吸收波长为650 nm,表观摩尔吸光率为2.59×104L.mol-1.cm-1。钴质量浓度在1.0 mg.L-1以内符合比耳定律。方法用于锌钴镀液中钴的直接测定,测得相对标准偏差(n=5)平均值为1.65%,平均回收率为100.5%。 相似文献
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以对环芳烷为基本骨架结构,经磺化、上保护和脱氢上碘反应合成了新的邻碘苯磺酸类催化剂4-磺酸基-5-碘-[2.2]对环芳烃,其结构经1H NMR, 13C NMR, IR, MS和元素分析表征。并以2,5-二甲基苯酚为底物,测试其催化效率。结果表明最佳反应条件为:催化剂用量为5 mmol%,在过硫酸氢钾复合盐(1 eq.)和10 mmol%四丁基硫酸氢铵存在下,在干燥碳酸二甲酯中于室温反应24 h,产物环化二聚体收率85%。 相似文献
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用甲基三辛基氯化铵和钨酸钠一步法合成甲基三辛基季铵钨酸盐离子液体[(CH3)N(n-C8H17)3]2W2O11,以该离子液体为催化剂,在无反应溶剂条件下催化过氧化氢氧化苯甲醇生成苯甲酸。 考察了反应温度、催化剂用量以及氧化剂过氧化氢用量对苯甲酸产率的影响。 确定优化条件:反应温度70 ℃,苯甲醇用量5 mmol,催化剂用量是底物的0.4%(摩尔分数),30%过氧化氢用量2 mL,苯甲醇的转化率可达99%,苯甲酸选择性为98%。 该方法具有反应条件温和、产率高和选择性好的优点。 相似文献
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新型可溶性偶氮聚酰亚胺及其作为液晶光定向层应用的初步研究 总被引:3,自引:1,他引:3
以 4 ,4′ 二 (1,2 苯二酸酐 4 羧酸酯 )偶氮苯为二酐单体 ,4 十六烷氧基 4′ ,4″ 二氨基三苯甲烷为二胺单体 ,通过缩聚反应合成了可溶性偶氮聚酰亚胺 .采用红外光谱、氢核磁共振、紫外光谱和热分析等手段 ,对产物的结构、热性能及光学性能等进行了表征 .在紫外光辐照下 ,上述聚合物表现出明显的光色效应 .经线性偏振紫外光 (LPUV)辐射后的上述偶氮聚酰亚胺定向层能诱导液晶盒中液晶分子发生定向沿面排列 ,且取向均匀 .上述实验表明 ,合成的偶氮聚酰亚胺是一类潜在的液晶光定向材料 . 相似文献
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本发明公开了4,5-二甲氧基邻苯二甲醛在水中铵氮检测中的应用及测定方法。具体的测定方法包括:(1)在铵氮工作液中依次加入EDTA-4Na溶液、4,5-二甲氧基邻苯二甲醛溶液、亚硫酸钠溶液,然后用氢氧化钠溶液调节体系的pH值,反应平衡后,在λex=379 nm下,测定400~600 nm的荧光曲线,记录最大发射波长处的荧光强度,做出工作曲线;(2)将样品溶液在最大发射波长处的荧光强度根据工作曲线定量样品溶液中的铵氮含量。本发明所述方法中,4,5-二甲氧基邻苯二甲醛与铵氮的反应平衡时间缩短至50 min,且反应产物的最大激发波长红移至接近可见光区,为便携式铵氮在线荧光检测仪的研制奠定基础。 相似文献
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锌-硫氰酸铵还原体系用于氢化偶氮苯的合成 总被引:1,自引:0,他引:1
氢化偶氮苯是重要的精细有机化工原料及中间体,染料工业用于制备联苯胺染料,医药工业用于生产解热镇痛药保泰松等[1]。传统的制备方法是在强碱性介质中用锌粉还原硝基苯,反应时间长,产率低[2]。用硫化铵快速还原偶氮苯生成氢化偶氮苯[3],则硫化铵用量大,刺激性气味对操作者及环境造成极大危害。我们采用NH4CNS的饱和溶液与锌粉组成还原体系,在25℃时还原偶氮苯,反应条件温和,锌粉用量少,时间短,产率高,操作简单。反应方程式如下:PhN=NpH(橙红色)Zn-NH4CNS25℃,EtOHPhNHNHPh(白色)1 实验部分在50ml圆底… 相似文献
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Kang JH Toita R Oishi J Niidome T Katayama Y 《Journal of the American Society for Mass Spectrometry》2007,18(11):1925-1931
The ionization of phosphorylated peptides is usually suppressed by non-phosphorylated peptides when alpha-cyano-4-hydroxycinnamic acid (CHCA) is used as a matrix for matrix-assisted laser desorption/ionization-time-of-Flight (MALDI-TOF) mass spectrometry analysis. In the present study, we examined the effect of diammonium citrate addition to the CHCA matrix on the detection of phosphorylated peptides. Substrates for protein kinase C (PKC) and c-Src were synthesized and phosphorylated by reaction with cell and tissue lysate samples. The addition of diammonium citrate to the CHCA matrix increased the sensitivity for distinguishing phosphorylated peptides from background noise. However, the effect depended on substrate concentration. 相似文献
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A. Ďurecová 《Journal of Radioanalytical and Nuclear Chemistry》1997,223(1-2):225-228
New method for simultaneous determination of228Ra and226Ra by using 3M's EMPORETM Radium Rad Disks in water has been developed. Both radionuclides226Ra and228Ra were counted through their daughter products,226Ra by conventional radon emanation techniques and228Ra through its daughter228Ac by using a proportional counter. Different molarity of diammonium hydrogen citrate were used for elution of228Ac and226Ra from EMPORETM Radium Rad Disks. 79% of228Ac was eluted in 10 ml of 0.0003M diammonium hydrogen citrate. The recovery of226Ra was 99% by using 40 ml of 0.2M diammonium hydrogen citrate adjusted by ammonium to pH 7.8. 相似文献
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Six peptides with various phosphorylation sensitivities for protein kinase A (PKA) were used for the simultaneous analysis of phosphorylated peptides using matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry. The mixture of six peptides was reacted with PKA and was analyzed by MALDI-TOF mass spectrometry. The intensity of all peaks except one phosphorylated peptide peak was very low (<20%). Moreover, we examined whether the addition of diammonium citrate to CHCA matrix at concentrations of 1–20 mg mL?1 can increase the peak intensity of peptides and phosphorylated peptides. The addition of diammonium citrate increased the peak intensity of peptides and phosphorylated peptides, but an increase in the intensity was unsatisfactory. Our study strongly suggests that MALDI-TOF mass spectrometry is not suitable for the simultaneous analysis of phosphorylated peptides. 相似文献
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A method is presented in which citrate is determined by complexation with excess of copper(II), followed by back-titration with EDTA. Small amounts of citrate can be determined by this method in the presence of large amounts of most organic acids present in natural products. Interfering reductants are removed by treatment with permanganate, amino-acids with nitrous acid, and metal ions with a cation-exchange resin. The indicator used for end-point detection is Szechromotrope, 4,4'-sulphonyl-bis(azobenzene) dichromotropic acid. 相似文献
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《Solid State Sciences》2004,6(9):1001-1006
A novel azobenzene derivative modified magadiite has been prepared by the reaction between the interlayer hydroxyl groups of magadiite and the azobenzene derivative using dodecyltrimethylammonium-exchanged magadiite as the intermediate. The formation of the silylated magadiite–azobenzene system was confirmed by X-ray diffraction, IR and MAS NMR spectroscopies. The organic groups of the azobenzene molecules are grafted onto the interlayer surface of magadiite by covalent bonding, affording compounds different from those derived by ion exchange. The orientation and reorientation of the azobenzene derivative in the magadiite have been examined through observing its photoinduced anisotropy behavior. 相似文献
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