排序方式: 共有52条查询结果,搜索用时 12 毫秒
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研究了HMCM-22分子筛催化邻苯二酚与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、异戊醛、正己醛、正辛醛、苯甲醛、二苯甲酮等十余种醛(酮)的缩合反应.考察了反应时间、酚与醛(酮)的配比、HMCM-22分子筛用量等因素对酚与醛(酮)反应的影响.结果表明,当酚与醛(酮)摩尔比为1∶1.4,催化剂用量为3.5 g/1mol醛(酮),反应5 h,选择性一般在97%以上,转化率也一般在70%以上,表明HMCM-22分子筛对邻苯二酚与醛(酮)的反应有较好的催化性能. 相似文献
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Acetalization of glycol with carbonyl compounds was carded out catalyzed by cupric p-toluenesulfonate. These carbonyl compounds included cyclohexanone, propionoaldehyde, n-butyraldehyde, /so-butyraldehyde, n-valeraldehyde, benzaldehyde and butanone. Satisfactory results were obtained: the conversions of these carbonyl compounds were more than 90%, the selectivities were higher than 99.1%, only 0.1% mole ratio of catalyst to substrate and 90 min were sufficient in most cases. The catalyst and products were separated easily by phase separation. 相似文献
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建立了超高效液相色谱-串联质谱法快速测定人体尿液中甜蜜素、糖精钠和安赛蜜3种甜味剂的方法。样品经过冷冻、解冻和高速离心后上清液用水直接稀释测定。目标化合物采用Waters ACQUITY UPLCHSS T3色谱柱(50×2.1mm,1.8μm)分离,以甲醇和含0.002mol/L乙酸铵的水溶液为流动相进行梯度洗脱,质谱采用电喷雾离子源电离、负离子多反应监测模式检测。甜蜜素、糖精钠和安赛蜜的平均回收率分别为101%、99.8%和108%,相对标准偏差分别为1.25%、2.00%和1.78%,检出限(S/N=3)分别为0.015μg/L、0.10μg/L和0.01μg/L。应用本方法测定200份尿液样品,甜味剂总检出率为97%。 相似文献
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在“星光Ⅱ”激光装置上进行了X射线辐射输运分解实验研究.实验中利用高时空分辨的MCP选通X射线皮秒分幅相机和软X射线条纹相机从缝口观测腔内壁X射线辐射时空分布,得到X射线在腔中的输运速率、X射线持续发射时间和轴向强度衰减量;利用X射线CCD针孔透射光栅谱仪观测到腔内X射线辐射光谱随空间位置的变化,得到X射线在输运过程中被多次吸收和发射后谱的变化特征;用X射线二极管和亚千X射线能谱仪分别得到源和输运末端X射线辐射总量和辐射温度.介绍了实验中采用的诊断技术和实验方法,并给出了获得的典型结果.
关键词: 相似文献
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研究了HY分子筛催化邻苯二酚与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、异戊醛、正己醛、正辛醛、苯甲醛、二苯甲酮等十余种醛(酮)的缩合反应.考察了反应时间、酚与醛(酮)的配比、HY分子筛用量等因素对酚与醛(酮)反应的影响.实验发现,当邻苯二酚与醛(酮)摩尔比为1:1.0、催化剂用量为每mol邻苯二酚2.5g、反应4h,选择性一般在97%以上,醛(酮)的转化率一般在57%以上,表明HY分子筛对邻苯二酚与醛(酮)的反应有较好的催化性能. 相似文献
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A novel carbon based strong solid acid catalyst has been synthesized successfully. The catalytic activity for acetalization and ketalization was investigated. The results showed that the novel catalyst was very efficient with the average yield over 92%. The novel heterogeneous catalyst also has the advantages of high activity, wide applicability even to the preparation of 7 membered ring acetals and ketals, strikingly simple workup procedure, non-pollution and reusability, which will contribute to the green process greatly. 相似文献