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1.
锆—7—(1—苯偶氮)—8—羟基喹啉—5—磺酸—Triton X—100荧光熄灭法测定锆 总被引:3,自引:1,他引:2
基于在pH=4.5~5.5、TritonX-100存在下、锆同7-(1-苯偶氮)-8-羟基喹啉-5-磺酸形成组成比为1:3的黄色络合物使荧光熄灭,建立了荧光熄灭测定锆的新方法。该方法的线性范围为0~28μgZrO2/L,检测限为0.5μg/L,体系稳定,灵敏度高,用于α-βAl2O3及瓷釉中锆的测定,结果满意。 相似文献
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以气体扩散膜为分离装置,流动注射进样冷蒸气发生法测定了土壤中的汞。试验了载流种类,流速,浓度,还原剂的浓度,流速,载气及春流速等分析参数对测定的影响。实验中观察到Cr(Ⅵ)对汞的响应信号有负干扰。方法的线范围为0-20μg/L,检出限为0.01μg/L,在2μg/L、5μg/L含量水平测定,方法的相对标准偏差(RSD)分别为1.5%和0.54%,回收率在91%-110%之间。 相似文献
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间接原子吸收测定硅酸盐中的钛 总被引:1,自引:0,他引:1
硅酸盐中微量钛的测定常用的是分光光度法。国外有报道用一氧化二氮-乙炔焰原子吸收测定钛,由于此法的精密度灵敏度及一些技术问题,在国内未被广泛应用,又由于钛本身的特性,使得空气-乙炔焰直接原子吸收测定成为不可能。本法利用元素钛对铁的线性增感效应,用空气-乙炔焰间接原子吸收测定了元素钛,同时借助离子交换进行干扰分离,并将此法应用到了硅酸盐中钦的测定。此法灵敏、简便、准确。该方法TiO_2标准曲线的线性范围为0.02—0.18μg/ml,特征浓度为0.0005μg/ml/1%A,相对标准偏差为2.8%。 相似文献
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蛋白质-钼(Ⅵ)-邻苯二酚紫-OP显色体系的研究及应用 总被引:3,自引:0,他引:3
建立了一种测定蛋白质的蛋白质-钼(Ⅵ)-邻苯二酚紫-OP显色体系光度法,蛋白质含量在0-50.0μg/mL范围内符合比尔定律。方法已应用于尿液、血清和豆浆中总蛋白测定,加标回收率90%-108%,相对标准偏差1.8%-3.0%(n=5),检出限4.0μg/mL。 相似文献
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在锆(钛)-对氯苯基荧光酮-CTMAB显色体系中,应用改进的人工神经网络解析锆和钛的吸收光谱,不经分离分光光度法同时测定锆和钛。在经典的BP算法的基础上改进了传递函数,引用双冲量因子,并对学习速率、动量因子采用自适应调整法,确定了网络的最佳参数。此方法避免了网络陷入过饱和,提高了网络的收敛速度和预测精度,优于经典的BP算法。用于钢样中锆和钛的测定,结果满意。 相似文献
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建立了氯化亚锡还原-硫氰酸铵快速光度法测定合金钢中钨的方法,方法的线性范围为2-400μg/50mL,相对标准偏差为0.24%-1.22%,方法简便,快速,测定结果准确。 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 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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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 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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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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Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 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