问题 问答题

化合物A最早发现于酸牛奶中,它是人体内糖代谢的中间体,可由马铃薯、玉米、淀粉等发酵制得.A的钙盐是人们喜爱的补钙剂之一,A在某种催化剂存在下进行氧化,其产物不能发生银镜反应.在浓硫酸存在下,A可发生如下反应.

试写出:

(1)化合物A、B、D的结构简式:

A______;B______;D______.

(2)化学方程式:

A-→E______;A-→F______.

(3)反应类型:A-→E______;A-→F______.

答案

A在浓硫酸存在下既能和乙醇反应,又能和乙酸反应,说明A中既有羧基又有羟基.A催化氧化的产物不能发生银镜反应,说明羟基不在碳链的端点上,可判断A为乳酸CH3CH(OH)COOH,而A被氧化可得CH3COCHO,不能发生银镜反应,这就进一步证明了A是乳酸.A与乙醇发生酯化反应生成B,B为CH3CH(OH)COOCH2CH3,A与乙酸发生酯化反应生成D,D为CH3COOCH(CH3)COOH,A在浓硫酸、加热条件下生成E,E可以溴水褪色,应发生消去反应,E为CH2=CHCOOH,A在浓硫酸、加热条件下生成六原子环状化合物F,结合F的分子式可知,为2分子乳酸发生酯化反应生成环状化合物,故F为

(1)由上述分析可知,化合物A为CH3CH(OH)COOH,B为CH3CH(OH)COOCH2CH3,D为CH3COOCH(CH3)COOH,

故答案为:CH3CH(OH)COOH;CH3CH(OH)COOCH2CH3;CH3COOCH(CH3)COOH;

(2)A→E是乳酸在浓硫酸、加热条件下发生消去反应生成CH2=CHCOOH,反应方程式为:

A→F是乳酸在浓硫酸、加热条件下发生酯化反应生成环状化合物

,反应方程式为:

故答案为:

(3)由(2)可知,A→E 属于消去反应,A→F属于酯化反应,故答案为:消去反应;酯化反应.

单项选择题 共用题干题
阅读理解

When did you last visit a shopping mall? In many places, the answer would be “last weekend.” Some people go even more often. Why? For one thing, malls offer goods and services that people need all in one place: food, clothing, things for their houses, entertainment, even medical services. So, are malls one of the highlights of modern civilization? Environmental activists would say No! They would go even further and say that consumer behavior is causing a huge environmental disaster. They cause consumers of ignorance of the side effect of their shopping—urban sprawl (扩大) .

Social scientists agree that patterns of development have changed the landscape a great deal in the last half century. Before 1950, most people lived in towns or cities and either walked to work or took public transportation. Only very wealthy people had automobiles. Farmers lived in rural areas or isolated villages and came into town only when they needed things they couldn’t produce themselves. If you gazed at the landscape you would see towns surrounded by countryside. Then a massive change occurred.

Automobiles became affordable and people were quick to adopt them. Now ambitious workers could live in the suburbs, the areas just outside cities, which started to grow rapidly. As long as there was lots of cheap land in the suburbs, no one paid much attention to the usage of that land. Malls, fast food restaurants, cinemas, and car dealerships spread out in large, flat buildings. These one–storey buildings and their parking lot took up a great deal space. Well– meaning farmers thought they were better off selling their land than growing crops. In ignorance, no one realized that once the land was built up in urban sprawl, the good farming land would be ruined forever. There was no way to preserve it.

Only in recent years have people come to mourn the old way of life as they have developed insight into the problems. Now people realize that urban sprawl has come with serious environmental problems. The negative aspects of sprawl include air and water pollution, loss of agricultural land, traffic jams, and the death of businesses in the old town centers. Many scholars think the time has come to analyze the problems better so we can develop appropriate policies to control further sprawl. Some think the best way to do is to educate citizens about their priceless environment.

小题1:What is mainly discussed in the passage?

A.Weekend Fun

B.Urban Sprawl

C.New Automobiles

D.Isolated Villages小题2:What does the underlined word “They” refer to in the first paragraph?

A.Scientists

B.Activists.

C.Farmers.

D.Malls小题3:Who do environmental activists blame for environmental problems?

A.Endangered animals.

B.Shopping mall owners.

C.Unthinking shoppers.

D.Ambitious farmers.小题4:What do scholars think should be done about urban sprawl?

A.Understand the situations better.

B.Follow customary policies.

C.Start school in shopping malls.

D.Charge polluters a lot of money.小题5:What is the scholars’ attitude toward urban sprawl?

A.Respectful.

B.Negative.

C.Positive.

D.Doubtful.