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1.
采用2,6-二羟甲基苯酚类化合物分别与单苯并冠醚(B15C5、B18C6)和二苯并冠醚(2B18C6、2B24C8、2B30C10)在酸催化下缩聚,合成了不同两个系列冠醚共缩聚物,这些聚合物M=1200-4500,可溶于氯仿等溶剂,萃取性能和络合选择性均有所提高。作为树脂使用,动态吸附容量为0.05-0.15mmol/g,并有较好的色谱特性。  相似文献   

2.
冠醚共缩聚物的合成与性能(Ⅱ)   总被引:1,自引:0,他引:1  
采用2,6-二羟甲基苯酚类化合物分别与单苯并冠醚(B15CS、B18C6)和M苯并冠醚(2B18C6、2B24C8、2B30C10)在酸催化下缩聚,合成了两个系列冠醚共缩聚物.这些聚合物M=1200—4500,可溶于氯仿等溶剂,萃取性能和络合选择性均有所提高.作为树脂使用,动态吸附容量为0.05—0.15mmol/g,并有较好的色谱特性.  相似文献   

3.
流动注射—火焰原子吸收光度法测定矿泉水中的锶   总被引:1,自引:0,他引:1  
张衍林 《分析化学》1995,23(2):180-182
用流动注射离子交换系统于酸性条件下在线富集饮用天然矿泉水中的锶、火粉原子吸收光度法测定,工存在分无干扰,方法简便快速,富集倍数可随意调节,在60h^-1的进样频率下,灵敏度提高17倍,用于矿泉水中锶的测定,当含量为60-250ng/ml时,相对标准偏差为0.68%-0.94%,回收率为94.4%-110.3%,检测限为15ng/ml。  相似文献   

4.
汽车氢化物空调机用贮氢合金的研究   总被引:1,自引:0,他引:1  
针对汽车发动机尾气废热为驱动热源的应用要求,研究了一对新的稀土系贮氢合金对La0.6Ml0.4Ni4.7Cr0.8-La0.2Mm0.8Ni4.35Fe0.65。该合金对在150~250℃/35~45℃/15~20℃工作温度下做制冷循环时,最大工作氢容量为4.5H/molM,理论特性系数COPc为0.74,可基本满足氢化物空调机应用要求。  相似文献   

5.
李永田  杨志勇 《分析化学》1995,23(3):297-298
本文用反相液相色谱法对同分异构体多环芳烃Qu和1,2-苯并蒽进行分离,固定其它全部色谱条件观察了30--7℃条件下的分离情况,结果发现,30-0℃左右,该两种物质始终不能分离,-4℃时见分离趋势,-7℃时分离较为满意,认为低温液相色谱可用于某些同分异构体等难分离物质的分离。  相似文献   

6.
卿笑天  刘红鸣 《分析化学》2000,28(7):842-845
使用4’-胆甾烯氧羰基苯并-15-冠-5气相色谱固定相建立了蔬菜中C1-C8脂肪酸及乳酸的定性1定量分析方法,测定的线性范围为0.10-50mg/L,RSD≤3.76%,回收率≥97.05%,该法快速,灵敏,准确,具有实用价值。  相似文献   

7.
首次介绍了一种以HZSM-5为载体,以La2O3为促进剂,采用浸渍法制成的Fe2O3-La2O3/HZSM-5新型催化剂,在常压,反应温度为300℃条件下,以H2O2为氧化剂使苯羟基化为苯酚,取得了苯的最高转化率和苯酚的选择性分别达到40.2%和94.0%的结果。  相似文献   

8.
牟峻  李庆才 《分析化学》1997,25(1):69-71
确立了粮谷和油籽中氯苯胺灵残留量的气相色谱测定方法,试样采用甲醇提取,经与正己烷液液分配,再以弗罗里硅土柱净化,毛细管柱气相色谱-氮磷检测器测定。方法简便、准确、检出限0.02μg/g,添加回收率为87.5-92.9%,相对标准偏差为3.5-7.0%。  相似文献   

9.
本文用分光光度法确定了25℃下配阳离子Cu(SCN)+在NaNO3-叔丁醇-水介质中的稳定常数。混合溶剂中叔丁醇组成为0,5,10,15,20和25wt%,离子强度范围为0.2~3.0mole·dm-3,溶液的pH=1.5~1.6。基于Pitzer理论用最小二乘多项式逼近法,确定了混合溶剂中配合物热力学稳定常数。讨论了配位反应的一级介质效应。  相似文献   

10.
高纯氧化钪中稀土杂质的电感耦合等离子体质谱法测定   总被引:5,自引:0,他引:5  
研究了用电感耦合等离子体质谱法测定高纯氧化钪中15个稀土杂质的方法。考察了基体效应及内标的作用,采用I或Cs为内标可很好补偿基体SC的影响。方法检测限为0.013-0.085ng/ml,加料回收率为91.2%-105.7%,相对标准偏 1.4%-8.1%。  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.
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   

13.
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   

14.
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   

15.
16.
《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   

17.
Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.  相似文献   

18.
A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.  相似文献   

19.
A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).  相似文献   

20.
Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO4 oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.  相似文献   

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