共查询到20条相似文献，搜索用时 78 毫秒
1.
以乙酸和异戊醇为原料,环己烷为带水剂,用732阳离子交换树脂催化合成乙酸异戊酯。探讨了催化剂用量、原料配比、反应时间、反应温度对合成乙酸异戊酯的影响。结果表明,合成较佳工艺条件：异戊醇0.1 mol、醇酸摩尔比1：1.7、环己烷6 mL、催化剂0.9 g,保温回流2 h,乙酸异戊酯的平均产率为54.6%。该催化剂重复使用6次后其催化活性开始降低。 相似文献
2.
四氯化锡催化合成己酸异戊酯 总被引：2，自引：1，他引：1
研究了用四氯化锡催化己酸和异戊醇合成己酸异戊酯的反应。考察了酸醇摩尔比、催化剂用量、反应时间、带水剂用量等因素对酯化率的影响。优化反应条件为：催化剂用量0.5g／0．08mol己酸,酸醇摩尔比1．0：1．4,用6ml环己烷/0．08mol己酸为带水剂,反应时间120min,酯化率可达96.28％。 相似文献
3.
4.
以固体超强酸为催化剂，用苯甲酸和异戊醇两种原料，直接酯化合成苯甲酸异戊酯．首先制备固体超强酸SO4^2-／TiO2，然后以此为催化剂进行酯化反应．反映过程中，考察了反应温度，原料配比，催化剂用量，反应时间等酯化反应的影响，由此确定最佳合成工艺条件：反应温度170℃，反应时间3h，异戊醇和苯甲酸摩尔比4：1，催化剂用量2％（以体系总质量计算）．由此条件下，其中苯甲酸异戊酯的收率达87．50％． 相似文献
5.
氯化铁催化合成马来酸二异戊酯 总被引：4，自引：0，他引：4
用六水三氯化铁为催化剂，由异戊醇和马来酸酐合成了马来酸二异戊酯，研究了影响反应的因素。当马来酸酐、异戊醇和三氯化铁的物质的量之比为1：4：0．11，回流分水60min，酯收率达95．3％。 相似文献
6.
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
7.
8.
用锗钨酸催化合成了水杨酸异戊酯,研究了催化剂用量、酸／醇摩尔比、反应温度、反应时间对酯收率的影响。当催化剂用量为反应物质量的１．３％、酸／醇摩尔比为１：２．５、反应温度为１３５～１５３℃、反应３ｈ,酯收率可超过９４％,在一定条件下催化剂可以重复使用多次。 相似文献
9.
用四氯化锡取代浓硫酸作为冰乙酸和正戊醇的酯化反应催化剂,成功地合成了乙酸戊酯。在探讨了酯化反应的历程后,找到了较好的反应条件:酸醇摩尔比为1、催化剂用量2.54%、反应时间为60m in,产率达89.9%。 相似文献
10.
负载型离子交换树脂催化合成乙酸异戊酯的工艺研究 总被引：1，自引：0，他引：1
对以强酸型阳离子交换树脂负载四氯化锡为催化剂,异戊醇和冰乙酸为原料合成乙酸异戊酯的工艺进行了研究,重点考察了催化剂用量、原料配比以及反应时间等因素对反应的影响。结果表明,冰乙酸和异戊醇的摩尔比为3.0∶1.0,催化剂用量为原料质量28%时,反应3h,酯化率达可达97.02%,纯度98.41%。优化后的工艺具有操作简单、时间短,对环境无污染、无腐蚀,产品纯度高等优点,且催化剂可重复利用。 相似文献
11.
12.
13.
《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
14.
罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
15.
《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
16.
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
17.
Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
18.
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
19.
20.
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