共查询到19条相似文献,搜索用时 578 毫秒
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季铵盐单体在蒙脱土中的插层原位聚合反应 总被引:6,自引:1,他引:6
通过四种结构相似的可聚合季铵盐(二甲基二烯丙基氯化铵、三甲基烯丙基氯化铵、丙烯酰氧乙基三甲基氯化铵、甲基丙烯酰氧乙基三甲基氯化铵), 通过蒙脱土层间构型排布的模拟及分析比较, 从分子水平上探讨了原位插层聚合反应中, 单体分子排列角度及构型对聚合反应的影响. 相似文献
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表面解吸常压化学电离质谱直接测定香辛蔬菜化学指纹 总被引:1,自引:1,他引:0
采用表面解吸常压化学电离质谱技术在无需样品预处理的前提下,对香辛蔬菜如韭菜、洋葱和大蒜的挥发性成分进行了快速检测,并对部分成分进行了二级串联质谱分析。 结果表明,韭菜叶片挥发性主要成分为2-甲基-2-戊烯、二甲基硫代亚磺酸酯、甲基烯丙基硫代亚磺酸酯等,其中二甲基硫代亚磺酸酯和甲基烯丙基硫代亚磺酸酯产生较强的M+H2O·+信号。 未切开的洋葱鳞茎挥发性成分质谱信号较弱,质谱图中主要是一些电晕放电产生的初始离子信号。 切开后的洋葱鳞茎挥发性成分质谱信号明显增强,主要是丙烯基次磺酸、丙基烯丙基硫代亚磺酸酯和二丙基硫代亚磺酸酯。 大蒜鳞茎挥发性成分主要是二烯丙基硫代亚磺酸酯。 切开后的大蒜鳞茎挥发性成分主要是丙烯基次磺酸。 实验对韭菜的二甲基硫代亚磺酸酯和甲基烯丙基硫代亚磺酸酯、洋葱的丙烯基次磺酸、大蒜的二烯丙基硫代亚磺酸酯进行了二级串联质谱分析。 表面解吸常压化学电离质谱技术无需样品预处理,分析速度快且对样品不造成破坏。 相似文献
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《应用化学》2010,(5)
采用表面解吸常压化学电离质谱技术在无需样品预处理的前提下,对香辛蔬菜如韭菜、洋葱和大蒜的挥发性成分进行了快速检测,并对部分成分进行了二级串联质谱分析。结果表明,韭菜叶片挥发性主要成分为2-甲基-2-戊烯、二甲基硫代亚磺酸酯、甲基烯丙基硫代亚磺酸酯等,其中二甲基硫代亚磺酸酯和甲基烯丙基硫代亚磺酸酯产生较强的M+H2O.+信号。未切开的洋葱鳞茎挥发性成分质谱信号较弱,质谱图中主要是一些电晕放电产生的初始离子信号。切开后的洋葱鳞茎挥发性成分质谱信号明显增强,主要是丙烯基次磺酸、丙基烯丙基硫代亚磺酸酯和二丙基硫代亚磺酸酯。大蒜鳞茎挥发性成分主要是二烯丙基硫代亚磺酸酯。切开后的大蒜鳞茎挥发性成分主要是丙烯基次磺酸。实验对韭菜的二甲基硫代亚磺酸酯和甲基烯丙基硫代亚磺酸酯、洋葱的丙烯基次磺酸、大蒜的二烯丙基硫代亚磺酸酯进行了二级串联质谱分析。表面解吸常压化学电离质谱技术无需样品预处理,分析速度快且对样品不造成破坏。 相似文献
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通过Knoevenagel缩合反应、用甲基肼闭环、再用碱进行酯的水解,得到目标产物1-甲基-3-三氟甲基-4-吡唑甲酸。以三氟乙酰乙酸乙酯为原料,对比原甲酸三乙酯和N,N-二甲基甲酰胺二甲基缩醛与之反应所得中间体对后续反应的优劣。 相似文献
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在CH2Cl2-H2O-NaCl溶液中,香叶醇的末端烯丙基经电解转变成烯丙基氯化物(2),2与二甲胺反应生成末端烯丙基胺(3),3再用过氧乙酸氧化形成烯丙基二甲基胺氧化物后,通过[2,3]-σ重排,再经锌粉还原得到辅酶Q10的重要中间体——2E,6E)-8-乙酰基-2,6-甲基-2,6-辛二烯-1-醇(7),7的结构经1H NMR和IR表征,且全为末端反式烯丙型醇。 相似文献
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The photodissociation of p-xylene at 266 nm in n-heptane and acetonitrile has been studied with use of nanosecond fluorescence and absorption spectroscopy. The p-methylbenzyl radical was identified in n-heptane and acetonitrile by its fluorescence, which was induced by excitation at 308 nm. The p-xylene radical cation was observed in acetonitrile by its absorption. In n-heptane, the decay rate of the S(1) state of p-xylene ((3.2 +/- 0.2) x 10(7) s(-1)) is equal to the growth rate of the p-methylbenzyl radical ((2.7 +/- 0.4) x 10(7) s(-1)), showing that the molecule dissociates via the S(1) state into the radical by C-H bond homolysis (quantum efficiency approximately 5.0 x 10(-3)). In acetonitrile, the formation of the p-xylene radical cation requires two 266 nm photons, and the decay rate of the radical cation ((1.6 +/- 0.2) x 10(6) s(-1)) equals the growth rate of the p-methylbenzyl radical ((2.0 +/- 0.2) x 10(6) s(-1)). This shows that the radical cation dissociates into the radical by deprotonation (quantum efficiency approximately 8.9 x 10(-2)). 相似文献
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二(对甲基苄基)二氯化锡和氢氧化钠溶液反应,合成了梯形结构二(对甲基苄基)锡氧(氯)簇合物,经X-射线衍射测定了其晶体结构。属三斜晶系,空间群为P1,晶体学参数a=0.979 52(16) nm,b=1.313 8(2) nm,c=1.419 5(2) nm,α=62.965(10)°,β=88.551(12)°,γ=73.709(11)°,V=1.550 5(5) nm3,Z=1,Dc=1.563 g·cm-3,μ(Mo Kα)=17.38 cm-1,F(000)=727,R=0.024 2,wR=0.057 9。簇合物为由Sn2O2构成的平面四元环形成的1个中心内环和2个由Sn2OCl(O)构成的平面四元外环组成的梯形结构。锡原子均为五配位三角双锥构型。对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及一些前沿分子轨道的组成特征。 相似文献
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Preparation of 2,6-dimethyl-4-arylpyridine- 3,5-dicarbonitrile: a paired electrosynthesis 总被引:1,自引:0,他引:1
Electrolysis of benzylthiocyanate, benzyl chloride, p-methylbenzyl chloride, p-methoxybenzyl chloride, or toluene in acetonitrile, at platinum electrodes in a two compartments cell divided by a glass-frit diaphragm, affords 2,6-dimethyl-4-arylpyridine-3,5-dicarbonitrile as major product. 相似文献
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螺环丙基杂环化合物是一类具有重要药理、生理活性的化合物, 研究和发展这类化合物的新的立体选择性合成方法是当前有机合成领域的一个热点. 对1,4-二氮杂双环[2.2.2]辛环(DABCO)衍生的氮叶立德与3-甲基-1-苯基-4-芳亚甲基-5-吡唑啉酮合成螺环丙基吡唑啉酮的反应做了研究, 并与胂叶立德所参与的类似反应的结果做了比较, 发现仅得到单一反式结构产物, 但存在exo和endo两种构型, 其中前者为主要产物. 产物结构由IR, MS, 1H NMR, 13C NMR, 元素分析和X射线衍射鉴定. 还从反应机理角度对两种叶立德性质对反应的影响做了解释. 相似文献
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The full low resolution fluorescence-excitation spectra of benzyl, benzyl-d7 and p-methylbenzyl in rigid amorphous solution at 77 K are reported, together with the polarization spectrum of the visible excitation band of p-methylbenzyl.The three excitation spectra are roughly similar in their low energy region appearing like weakly allowed spectra having stronger “forbidden” components. The three spectra more or less agree with the mirror image of the benzyl and benzyl-d7 fluorescences. The emission of p-methylbenzyl is strikingly different, showing a considerable relative strengthening of the allowed portion over the “forbidden” component and, with that, an apparent strong break with the absorption fluorescence mirror image rule.One interpretation anticipates an important effect of geometry change in pMB, due to electronic excitation, upon both the allowed and “forbidden” components of this well known weak transition. Alternatively, it may be that the elusive second excited state (2B2) appears in the pMB excitation spectrum in such a coincident manner that the mirror image rule holds even while conferring upon the excitation spectrum a structure very much like the absorption and emissions of the two benzyl radicals. This second state, in any case, is supposed to lie very near tthe first excited (2A2?) state. The polarization results in pMB are consistent with either interpretation. Since theoretical predictions indicate that the ratio of 2B2? to 2A2? intensity should be much larger in p-methylbenzyl than in benzyl, it may well be that the 2B2? band is an important part of the excitation spectrum in the latter case. The necessary coincidence of energy and intensity required of the 2B2? transition with what should characterize the nontotally symmetric vibronic activity in the 2A2? transition is a complicating factor which these low resolution studies are not able to overcome in trying to resolve this question. 相似文献