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磷钨杂多酸催化合成丙酸丁酯 总被引:2,自引:0,他引:2
以磷钨杂多酸为催化剂,通过丙酸和丁醇反应合成丙酸丁酯,研究了各有关因素对丙酸酯化率的影响.实验证明,磷钨杂多酸是合成丙酸丁酯的良好催化剂.在酸醇物质的量比为1:1.2,催化剂用量1.0%(占反应物总质量的百分数),带水剂环己烷10mL/0.2mol丙酸,反应时间为80min,反应温度100~115℃的条件下,丙酸的酯化率可达99.3%. 相似文献
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以糠醇和丙酰氯为原料,以吡啶为催化剂,无水碳酸钠为缚酸合成了丙酸糠醇酯,并考察了反应物的配料比,催化剂,缚酸剂,带水剂的用量等因素对反应的影响。 相似文献
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用2-溴丙酸与乙醇酯化,按n(C2H5OH)/n(CH3CHBrCOOH)=1.5,以对甲苯磺酸为催化剂,苯为带水剂,在80℃左右加热回流反应3.5h,合成2-溴丙酸乙酯,经蒸馏后得2-溴丙酸乙酯,其质量分数为98.6%,收率为94.7%. 相似文献
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钼镍粉催化合成丙酸异丁酯的绿色合成研究 总被引:3,自引:0,他引:3
以丙酸和异丁醇为原料,以改性钼镍粉取代以往常用的硫酸作催化剂,进行了丙酸异丁酯的合成研究.该催化剂的制作原料广、价廉,制作方便,催化活性高,能反复使用,不腐蚀设备、污染环境,在工业上制取丙酸异丁酯有推广和应用价值.经实验确定最佳反应条件为:n(异丁醇)/n(丙酸)=1.3∶1,催化剂用量为反应物总质量的3%,反应时间为2h,反应温度105~125℃.上述条件下,丙酸异丁酯的收率可达85%. 相似文献
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以四氯化锡为催化剂,正丙酸和异戊醇为原料合成了丙酸异戊酯.最佳合成条件:以0.2mol正丙酸为基准,醇酸摩尔比1.3:1,催化剂用量2.0g,反应时间为1.0h,最后酯化率为92.3%.研究表明该催化剂具有催化活性高、稳定性好、价廉易得、后处理工艺简单、不需要加带水剂、无腐蚀性、不污染环境以及能重复使用等优点. 相似文献
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首次利用共价型(C1)化物为催化剂,用邻苯二甲酸酐与丁醇反应合成了DBP增塑剂,并考察了带水剂、催化剂用量、醇用量、反应温度、反应时间等因素的影响.结果表明,在本催化剂条件下可以避免使用具毒性的甲苯、二甲苯的带水剂. 相似文献
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以低廉的膨润土为载体原料,采用浸渍法制备了固体超强酸SO42-/TiO2/膨润土;再以氯乙酸和异丁醇为原料,SO42-/TiO2/膨润土为催化剂,催化合成了氯乙酸异丁酯。探讨了SO42-/TiO2/膨润土对酯化反应的催化活性,研究了原料醇酸摩尔比、反应时间、带水剂选择、带水剂用量、催化剂用量、催化剂重复使用性等反应条件对酯化反应的影响。结果表明:在氯乙酸用量为0.20mol,醇酸摩尔比为1.2∶1,催化剂用量为0.5g,反应时间为3h,带水剂环己烷用量为5mL时,酯化率可达99.27%,催化剂重复使用6次后仍具有较高活性。表明SO42-/TiO2/膨润土催化剂具有稳定的催化活性。 相似文献
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用维生素C作催化剂,环己烷作带水剂,以草酸与正丁醇为原料合成了草酸二丁酯;考察了醇酸摩尔比、催化剂用量、带水剂用量、反应时间对草酸二丁酯收率的影响。结果表明,维生素C有着良好的催化活性,在草酸用量0.1 mol,醇酸摩尔比3.5∶1、催化剂用量为反应物总质量3.0%、环己烷用量32mL条件下回流反应40 min,草酸二丁酯收率可达94.8%。 相似文献
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以硅胶负载硅钨酸为催化剂,通过丁醛与1,2-丙二醇反应合成了丁醛1,2-丙二醇缩醛.较系统地研究了醛醇量比、催化剂用量、带水剂用量及反应时间等条件对收率的影响.结果表明:在丁醛用量为0.20 mol,n(丁醛)∶n(1,2-丙二醇)=1∶1.3,催化剂用量为0.1 g,环己烷为带水剂用量为4 mL,反应时间30 min的优化条件下,丁醛1,2-丙二醇缩醛的收率可达82.6%. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献