共查询到20条相似文献,搜索用时 78 毫秒
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取代芳杂环及其苯并物在溶液中的互变异构平衡实验结果已有大量报道。互变异构体的芳性或共振能(RE)被广泛用于定性解释互变平衡的移动趋向,Katritzky 等并从互变平衡实验数据得出吡啶酮、喹诺酮和异喹诺 相似文献
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本文提出呋喃甲醛、二甲基呋喃,噻吩甲醛,毗咯甲醛和呋喃丙烯酸的质谱断裂速率决定步骤的机理,采用CNDO/2方法计算了这些化合物的分子离子及其碎片的各种量子化学参量,定量地解释了它们的质谱峰高,从芳碳环共轭体系推广到芳杂环共轭体系。 相似文献
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利用精密的流动混合微量热法测定了298.15 K时D/L-色氨酸、L-色氨酸、L-组氨酸和L-苯丙氨酸四种天然芳香族氨基酸水溶液的稀释焓, 根据所建立的拟等步自堆叠作用的化学模型对实验数据进行了处理, 计算得到模型参数K△Hm. 该化学作用参数与McMillan-Mayer理论模型中的焓对作用系数具有高度一致性, 即hxx=K△Hm. 结合文献报道的结果, 认为芳核π-π自堆叠作用在本质上是一种特殊的疏水-疏水作用, 一般表现为吸热效应; 取代基空间位阻、芳核以外部分的静电、氢键和手性选择性作用等对芳核π-π自堆叠作用有显著影响; 组合参数K△Hm实际上描述了芳核π-π自堆叠作用平衡及焓变的综合效应. 相似文献
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Reaction of substituted benzene rings with N‐bromophthalimide, under neutral conditions, gave the corresponding bromo derivatives with a preference for the formation of the para bromo isomer over the ortho isomer. The simple work‐up procedure minimizes loss of product and the yields are good. 相似文献
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Keng‐Shiang Huang Sie‐Rong Li You‐Feng Wang Yu‐Li Lin Yung‐Hua Chen Tzu‐Wei Tsai Chih‐Hui Yang Eng‐Chi Wang 《中国化学会会志》2005,52(1):159-167
Synthesis of some benzoheterocyclic compounds like substituted benzofurans, 4‐methyl‐2H‐chromenes and 3,4‐dihydro‐2H‐benzo[b]oxepin‐5‐ones from 2‐hydroxyacetophenone via base induced cyclization and ring‐closing metathesis (RCM) is described. 相似文献
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Synthesis of Aromatic Ketones from Aromatic Compounds Using Vanadium‐Containing Mesoporous Silicates
Aromatic ketones were synthesized from aromatic compounds via liquid‐phase oxidation at 60 °C and 1 atm over vanadium‐containing MCM‐41 catalysts using a batch reactor. The catalysts were prepared by direct hydrothermal (4V‐MCM‐41) and wet impregnation (9V/MCM‐41) methods. Their physico‐chemical properties were determined with various characterization techniques. For the oxidations of all substrates in this work, 4 V‐MCM‐41 exhibits superior catalytic performance than 9 V/MCM‐41 due to its larger values of unit cell parameter, BET surface area, and vanadium dispersion as well as stronger oxidation ability of vanadium‐oxygen species. Apparently, the single site, isolated vanadium centers in 4V‐MCM‐41 possess much higher activity (based on the turnover number) than those containing more vanadium atoms in 9V/MCM‐41. In addition, the substrate activities decrease in the order of diphenylmethane > fluorene > 9,10‐dihydroanthracene > ethylbenzene ≥ 4‐nitroethylbenzene, which are attributed to their distinct molecular structures. 相似文献
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液晶性芳香醛化合物的合成 总被引:2,自引:0,他引:2
以对羟基苯甲醛和对烷氧基联苯酰氯为原料,采用爱因宏反应,合成了一系列4-(4'-烷氧基联苯基-4-羧基)苯甲醛.化合物的结构通过元素分析、红外光谱、核磁共振和质谱等方法确证.化合物的液晶行为用示差扫描量热法、偏光显微镜和旋光仪等方法表征.结果表明,所有的化合物加热至各自的熔点以上都能形成液晶态.在液晶态可以观察到手性近晶C相、近晶相、胆甾相和向列相的典型织构.含手性中心的化合物都有较高的旋光性,而且在合成反应中旋光性得到保持.随着分子末端烷氧基碳原子数增加,化合物(除2a和4a外)的熔点(Tm)和液晶态的清亮点(Ti)呈规律性变化,近晶相范围和近晶相-向列相转变温度渐增,而向列相温度范围递减,至十二烷基时,仅呈现近晶性. 相似文献
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液晶性芳香酰胺化合物的合成 总被引:7,自引:0,他引:7
合成了一系列炖粹以酰胺基为中心桥键的刚性芳香酰胺小分子化合物,并对其作了表征,发现其中有些化合物具有液晶性。酰胺键之间能形成很强的分子间氢键,使芳香酰胺小分子化合物的熔点很高,难于形成液成液晶态。研究发现,如果在这类化合物的中心苯环上引入合适的取代基以减弱分子间氢键,同时引入合适的末端基时,则可使芳香酰胺化合物生成液晶相的能力增强。 相似文献
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《合成通讯》2013,43(24):4221-4227
Abstract Lead/ammonium acetate is a convenient reagent for the reduction of aromatic nitro compounds to the corresponding symmetrically substituted azo compounds. Various azo compounds containing additional reducible substituents such as halogen, nitrile, acid, phenol, ester, methoxy, etc., functions have been synthesized in a single step by the use of this reagent. The conversion is reasonably fast, clean, high yielding and occurs at room temperature in methanol. 相似文献