动态诱导效应是一种暂时的效应，不一定反 映在分子的物理性质上，不能由偶极矩等物理性 质的测定来比较强弱次序。比较科学、可靠的方 法是根据元素在周期表中所在的位置来进行比较

在成键原子间电子云并非完全对称分布， 而是偏向电负性较高的原子一边，这样形成的 共价键键就具有了极性（polarity），称为极性 共价键或极性键

H ydrocarbons that contain carbon-carbon triple bond are called alkynes. Non- cyclic alkynes have the molecular formula C, H2n-2. Acetylene (HCCH) is th simplest alkyne. We call compounds that have their triple bond at the end of a carbon chain(RC=CH) monosubstituted, or terminal, alkynes. Disubstituted alkynes (RCCR') are said to have internal triple bonds. You will see in this chapter that a car- bon-carbon triple bond is a functional group, reacting with many of the same reagents

第一节醇的定义和分类 第二节醇的命名 第三节醇的结构特点 第四节醇的物理性质和光谱特征 第五节醇的反应 第六节醇的制备

一、基本概念 1、碳水化合物基本含义: 组成符合Cn(H2O)m通式 2、单糖、二糖、低聚糖、多糖; 还原糖、非还原糖 3、变旋现象(单糖的 Haworth结构中讲) 4、差向异构(单糖的立体构型中讲)

W hen we discussed elimination reactions in Chapter 5, we learned that Lewis base can react with an alkyl halide to form an alkene. In the present chapter, you will find that the same kinds of reactants can also undergo a different reaction, one in which the Lewis base acts as a nucleophile to substitute for the halide substituent on carbon

Ikenes are hydrocarbons that contain a carbon-carbon double bond. A car- bon-carbon double bond is both an important structural unit and an important functional group in organic chemistry. The shape of an organic molecule is influ- enced by the presence of this bond, and the double bond is the site of most of the chem- ical reactions that alkenes undergo. Some representative alkenes include isobutylene(an industrial chemical), a-pinene (a fragrant liquid obtained from pine trees), and farnesene (a naturally occurring alkene with three double bonds

tructure* is the key to everything in chemistry. The properties of a substance depend on the atoms it contains and the way the atoms are connected. What is less 0 obvious, but very powerful, is the idea that someone who is trained in chemistry can look at a structural formula of a substance and tell you a lot about its properties

1.色谱法:起源与发展: 特点:分离分析技术;分析有色 物质、无色物质。 本质:色谱柱高选择性的高效分 离作用与高灵敏度检测技术的结合。 分类(流动相状态):气相色谱、 液相色谱、超临界色谱

drogen peroxide is formed in the cells of plants and animals but is toxic to them. neemen Consequently, living systems hav developed mechanisms to rid themselves of hydrogen peroxide, usually by enzyme-catalyzed reduction to water. An under- standing of how reactions take place, be they reactions in living systems or reactions in