共查询到19条相似文献,搜索用时 78 毫秒
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以4-羟基-3-硝基香豆素为起始原料,经过开环、脱羧,得到2-硝基-2,-羟基苯乙酮,再和甲氧胺盐酸盐反应生成中间体1-(2-羟基苯基)-2-硝基-乙酮-O-甲基肟。最后通过碱性条件下关环得到苯并呋喃-2,3-二酮3-(O-甲基-肟)2-肟。目标化合物及中间体结构经1H-NMR确证。反应总收率70.4%,产品纯度99.2%。该工艺原料廉价,操作简单,收率较高,具有较好的工业化应用前景。 相似文献
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以丁酮肟和2,4-二氯氯苄为原料合成了O-2,4-二氯苯甲基丁酮肟醚,再用盐酸水解得到了O-2,4-二氯苯甲基羟胺盐酸盐。文章系统研究了反应温度、不同溶剂、溶剂含水量等各种实验因素对O-2,4-二氯苯甲基丁酮肟醚合成的影响,研究了盐酸浓度、原料配比等因素对O-2,4-二氯苯甲基丁酮肟醚水解工艺的影响。两步收率最高分别为94.5%和85.0%。产物熔点为167.7~169.9℃。 相似文献
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从克拉霉素的前体 6 O 甲基 2′, 4″ 二 (三甲基硅 ) 红霉素A 9 ( 1 异丙氧基环己基 )肟出发,在φ(C2H5OH) =50%的乙醇水溶液中加入甲酸,加热回流 2h脱去保护得到 6 O 甲基红霉素A9 肟,将它悬浮于水中,在w(HCl) =1%的盐酸水溶液作用下水解去除 3 克拉定糖得到目标化合物 3 羟基 6 O 甲基红霉素A9 肟,它是合成对耐药菌有优良活性的第三代红霉素酮内酯和酰内酯的重要中间体, 收率为 73 3%。为了简化反应步骤,试探了在脱保护一步不分离产物而在w(C2H5OH) =95%的乙醇和w(HCl) =2%的盐酸水溶液反应体系中直接水解脱糖的方法,得到了目标化合物,总收率为 69 0%。通过1HNMR、13CNMR和MR确定了目标化合物的结构。 相似文献
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HR Bahari HA Sidek FR Adikan WM Yunus MK Halimah 《International journal of molecular sciences》2012,13(7):8609-8614
Heavy metal oxide glasses, containing bismuth and/or lead in their glass structure are new alternatives for rare eart (RE) doped hosts. Hence, the study of the structure of these vitreous systems is of great interest for science and technology. In this research work, GeO(2)-PbO-Bi(2)O(3) glass host doped with Er(3+)/Yb(3+) ions was synthesized by a conventional melt quenching method. The Fourier transform infrared (FTIR) results showed that PbO and Bi(2)O(3) participate with PbO(4) tetragonal pyramids and strongly distort BiO(6) octahedral units in the glass network, which subsequently act as modifiers in glass structure. These results also confirmed the existence of both four and six coordination of germanium oxide in glass matrix. 相似文献
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《Inorganic chemistry communications》1999,2(7):283-287
[Rh(μ-OMe)(COD)]2 reacts with tris-ortho-tert-butylphenylphosphite in the presence of carbon monoxide to provide the first example of a stable dinuclear carbonyl-phosphite rhodium(0) complex with a metal–metal bond distance of 2.73(1) Å. The geometry at the metals is different: square planar and distorted trigonal bipyramid. The crystallographic data indicate that two of the carbonyl ligands are semi-bridged between the two rhodium atoms. 相似文献
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Summary For neutral and FeCl3-doped poly(3-butylthiophene) (P3BT) and poly(3-dodecylthiophene) (P3DDT), conductivity measurement and thermal analysis are performed. Before doping, the glass transition temperatures (Tg) of the P3BT and P3DDT are 75.4°C and 5.6°C respectively. No melting transition of an ordered phase for P3BT is observed. But for P3DDT, the melting temperatures of ordered side chains and main chains are 56.1°C and 116.3°C respectively. Upon doping, the Tg 's shift upward to 150.5°C and 51.2°C for P3BT and P3DDT respectively and the two melting peaks of the ordered phases of P3DDT disappear. The dopant anions decompose in the range of about 150 to 230°C. The conductivities increase with increasing temperature and reach maxima at 135°C and 28°C and drop sharply in the range of 160–200°C and 130–170°C for P3BT and P3DDT respectively. This indicates that the thermal motion of the main chains would lead to a drop of conductivity due to thermal undoping, while the dopant decomposition would lead to a rapid loss of conductivity and an occurrence of crosslinking reaction. 相似文献
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(1-x)Pb(Zn_(1/3)Nb_(2/3))O_(3-x)PbTiO_3(PZNT)晶体是弛豫铁电体Pb(Zn_(1/3)Nb_(2/3)O_3与普通铁电体PbTiO_3组成的具有钙钛矿结构的固溶体,其准同型相界成分(x=0.09)附近表现出极其优异的压电性能,在医用超声成像、声纳、微位移器等方面具有广阔的应用前景,分析了PZNT-PbO赝二元系的析晶行为和相关系,总结了PZNT晶体的压电性能,讨论了生长工艺和成分对晶体性能的影响。针对PZNT晶体生长中存在的问题,发展了助熔剂-坩埚下降法、通气诱导成核技术、两步法生长工艺、区熔凝固技术、底部籽晶高温溶液法等多种生长技术,生长出大尺寸的PZNT晶体,并比较了这些生长技术的特点。 相似文献
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制备 Pb(Zn_(1/3)Nb_(2/3))O_3(PZN)基陶瓷电容器,最主要的问题是形成有害于介电性质的焦录石相。实验表明,固相反应法很难合成钙钛矿结构的 PZN 陶瓷,于1000经固相反应的产物是含立方焦录石的混合物,在 PZN 中添加0.53mol 的 PFW,试样中的钙钛矿相超过97%。通过对 Pb(Fe_(2/3)W_(1/3))O_3(PFW)结晶化学和烧结机理的分析,证明在 PZN 中添加 PFW 能减少或抑制焦录石的形成。本文报导了 PZN-PFW 二元系陶瓷的相关系和介电性质,探讨了钙钛矿相的形成机理。 相似文献
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