邻苯二甲醛的简易合成工艺

研究了邻二—(二氯甲基)苯在冰乙酸条件下，滴加少量浓硫酸，酸解合成邻苯二甲醛各反应条件的影响；实验结果表明：邻二—(二氯甲基)苯与浓硫酸摩尔比为1：4，反应温度在90—100℃，反应时间为90min，邻苯二甲醛的收率可达92．3％．     

一锅法合成N-羟基邻苯二甲酰亚胺

通过对目前国内外N-羟基邻苯二甲酰亚胺主要合成方法的对比研究,以邻苯二甲酸酐作为原料,用一锅法合成了目标产物,获得了较高的产率和纯度,减少了反应时间,优化了合成路线,实现了环境友好.     

聚苯乙烯—吡啶树脂催化合成N—取代邻本二甲酰亚胺

以聚苯乙烯－吡啶树脂为催化剂，催化合成了两种Ｎ－取代邻苯二甲酰亚胺，催化效果良好，催化剂可重复使用。     

氧代-双（N-甲基邻苯二甲酰亚胺）合成工艺研究

氧代-双(N-甲基邻苯二甲酰亚胺)(OBI)是合成聚酰亚胺的重要单体ODPA的中间体．非质子性溶剂中,催化剂存在下4-硝基-N-甲基邻苯二甲酰亚胺能发生自缩合反应,生成结构对称的氧代-双(N-甲基邻苯二甲酰亚胺)．文章考察了催化剂种类、催化剂用量、反应时间、反应温度对其合成收率的影响,确定了适宜的合成条件,并通过红外光谱对产品结构进行了表征．     

顶空气相色谱法测定氨氯地平中间体中残留苯及其同系物的含量

建立了顶空气相色谱法测定氨氯地平中间体邻苯二甲酰亚胺氨氯地平(PHTHALOYL AM LOD IP INE)中残留苯、甲苯、对二甲苯、间二甲苯和邻二甲苯的方法。实验结果表明:苯、甲苯、对二甲苯、间二甲苯和邻二甲苯均在0.1-64ΜG/ML浓度范围内呈良好的线性关系,相关系数分别为0.9992、0.9994、0.9987、0.9993和0.9995;加标回收率和相对标准偏差分别在96.2%-103.7%和2.7%-3.4%之间。本法操作简便,结果准确,是测定药物中间体中残留有机溶剂苯、甲苯、对二甲苯、间二甲苯和邻二甲苯的有效方法。     

一水邻苯二甲酸钙的热分解及其脱水动力学分析

采用TG-DTA分析研究了一水邻苯二甲酸钙热分解过程,对其中的脱水过程进行了动力学计算. 由Friedman和Ozawa-Flynn-Friedman法得到脱水过程的活化能和指前因子,用Archar方法计算拟合了几种机理函数,确定了脱水过程的优化动力学参数及最佳机理模型. 脱水过程的活化能Ea为141.1576 kJ/mol,反应的机理模型为Bna,即f(α) =(1-α)n*αn.     

交叉羟醛缩合反应制二苯叉丙酮实验的研究

研究了交叉羟醛缩合反应制二苯叉丙酮实验中原料液存放时间、存放方武、NaOH浓度对产率的影响,推测了反应中出现的油状副产物,提出了获得较好实验效果的条件.     

相转移催化下的合成安息香缩合反应研究

以PEG-6000为相转移催化剂,VB1为催化剂,合成了二苯羟乙酮(安息香),找出了最佳反应条件:PEG-6000的用量为1.5 g、反应温度为50℃、回流时间80 m in、氢氧化钠浓度10%(5 m l),反应生成物产率达70.8%-80.2%,重现性达100%。     

聚苯乙烯-吡啶树脂催化合成N-取代邻苯二甲酰亚胺

以聚苯乙烯－吡淀树脂为催化剂，催化合成了两种Ｎ－取代邻苯二甲酰亚胺，催化效果良好，催化剂可重复使用。     

3,4,5-三氟溴苯的合成工艺的改进

为了改进以2,3,4-三氟苯胺为原料合成3,4,5-三氟溴苯的传统工艺中存在的产品产率低、副产物产率高和生产成本高的缺点,该实验将溴化反应过程中溴素用量减少一半,溴化后用过氧化氢氧化产生的溴化氢,使之转化为溴素后再进行溴化反应.并采用了单因素分析法探讨了改进后的合成工艺的最佳合成条件:溴化反应温度为36℃～45℃,溴化反应时间范围是8～9h,硫酸与冰醋酸最佳配比为1:0.15,亚硝酸钠与次磷酸钠最佳配比为1∶0.930.在此工艺条件下,3,4,5-三氟溴苯的产率≥76.0％,副产物1,2-二溴-3,4,5-三氟苯产率为3.0％.由于溴素、冰醋酸和亚硝酸钠等辅料的用量比传统工艺少,使得生产成本大幅降低,并且基本达到了提高产品产率和降低副产物产率的目的.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

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?     

Western and Eastern culture differences in commercial field

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.     

只要努力,不要后悔

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.     

浅谈移民问题

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.     

风的曲线

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.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

Sister Carrie, an Adherent of Desires

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.