首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
本文研究了新显色剂7-(2-羧基-4-溴-苯偶氮)-8-羟基喹啉-5-磺酸与锌的反应条件,试验结果发现在乳化剂OP存在下,酒石酸介质中新试剂与锌形成稳定配合物,其最大吸收波长为500nm,表观摩尔吸光系数为1.15×10 ̄5L·mol ̄(-1)·cm ̄(-1),Zn ̄(2+)浓度在0~8μg/mL之间符合比尔定律,方法用于茶叶中微量锌的测定结果满意。  相似文献   

2.
初探了反-2-苯基-邻-硝基肉桂酸(PNCA)的高效液相色谱分离,优选出了最佳分离条件。所建立的方法简单、快速,适用于工业生产中的控制及分析。  相似文献   

3.
钴(Ⅱ)在HAc-NaNO_2-吐温-80-NPTSQ体系中有一灵敏的阴极极化导数波,其峰电位-1.00V(vs.SCE),钴浓度在4.0×10 ̄(-9)~3.0×10 ̄(-7)g/mL范围内与峰电流有良好的线性关系。本文讨论了测定钴(Ⅱ)的最佳实验条件,对极谱波的性质进行了初步探讨,并作了维生素B_(12)中钴的测定,测定结果的相对标准偏差为3.74%,回收率为96~108%。  相似文献   

4.
3-苯基-5-取代苯氨基-6-甲基-1,2,4-三嗪的合成陆忠娥,曾润生,席海涛(苏州大学化学系,苏州,215006)关键词硫代苯甲酰胺,α-乙酰基硫代甲酰苯胺,N'-氨基苯甲脒,3-苯基-5-取代苯氨基-6-甲基-1,2,4-三嗪1,2,4-三嗪类...  相似文献   

5.
以环戊酮、正戊醛为原料,采用相转移催化技术进行羟醛缩合,经脱水得到2-戊叉环戊酮,再经异构化,合成了2-戊基环戊-2-烯酮。文章对相转移催化合成2-戊叉环戊酮及其异构化的条件进行了研究。  相似文献   

6.
用新合成的偶氮试剂2-(5-硝基-2-吡啶偶氮)-5-二甲氨基苯胺(5-NO_2-PADMA)研究了光度法测定他的反应条件。结果表明,在0.45~1.2mol/L盐酸介质中,钯与试剂形成稳定的蓝色配合物,其最大吸收波长位于621nm处,表观摩尔吸收系数为9.4×10 ̄4L·mol ̄(-1)·cm ̄(-1),配合成的组成为Pd:5-NO_2-PADMA=1:2,钯浓度在0~10μg/10mL范围内符合比尔定律。本方法是目前测定钯的高灵敏度和高选择性体系之一。用于含钯分子筛及二次合金管理样-88中微量钯的测定,结果满意。  相似文献   

7.
研究了在氯化氢-乙醇溶液或乙醇溶液中,2,4-二羟基苯乙酮与甲醛和芳胺的Mannich反应,分别得到了5个2,4-二羟基-3-芳氨基甲基苯乙酮和5个8-乙酰基-3-芳基-3,4-二氢-5-羟基-2H-1,3-苯并嗪新化合物。用元素分析、IR、1HNMR、MS、UV确定了它们的结构,并成功地实现了2,4-二羟基-3-芳氨基甲基苯乙酮和8-乙酰基-3-芳基-3,4.二氢-5-羟基-2H-1,3-苯并嗪二类化合物的转化。  相似文献   

8.
γ-甲基-δ-酮己酸,γ-异丙基-δ-酮己酸在碘化N-甲基-2-氯吡啶盐存在下分别同(R)-四氢噻唑-2-硫酮-4-羧酸乙酯反应,得到光学活性的(R)-N-(γ-甲基-δ-酮己酰基)四氢噻唑-2-硫酮-4-羧酸乙酯(1a)及光学活性的(R)-N-(γ-异丙基-δ-酮己酰基)四氢噻唑-2-硫酮-4-羧酸乙酯(1b)。1a,1b分别同(R,S)-α-苯乙胺反应得到光学活性的酰胺2a,2b,同时使(R,S)-α-苯乙胺拆分,得到光学活性的α-苯乙胺。  相似文献   

9.
探讨题示试剂(DMTAQ)与锌离子的显色反应条件,当pH为5.5,在TritonX-100存在下,DMTAQ与锌离子形成红色配合物,最大吸收峰位于545nm,表观摩尔吸光系数9.4×10 ̄4L·mol ̄(-1)·cm ̄(-1),锌量在0~25μg/50mL范围内符合比尔定律。该法可用于测定人发中的微量锌。  相似文献   

10.
对钴与4-[(5-氯-2-吡啶)偶氮]-1,3-二氨基苯(5-Cl-PADAB)形成络合物的吸收光谱进行探讨,结果表明:试剂及络合物在不同酸度条件下形成不同型体。在酸性条件下,络合物为大阳离子,钴离子以三价形式存在,钻与试剂的络合比为1:2。在强酸性介质中,将此络合物用于光度测定钻,方法选择性及稳定性好,且灵敏度极高。对水、粮食、土壤、茶叶及维生素B_(12)中微量钻进行直接测定,获得满意结果。  相似文献   

11.
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   

12.
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
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   

18.
19.
《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   

20.
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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号