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

ow that we've reviewed the various bonding models, we are ready to examine organic compounds in respect to their structure, reactions, properties, and appli cations. Were we to list the physical and chemical properties of each of the more than million organic compounds separately, it would tax the capacity of even a pow- erful computer. Yet someone who is trained in organic chemistry can simply look at the structure

first three chapters established some fundamental principles concerning the structure of organic molecules. In this chapter we begin our discussion of organic chemical reactions by directing attention to alcohols and alkyl halides. These two rank among the most useful classes of organic compounds because they often serve as starting materials for the preparation of numerous other families

一. 电环化反应(Electrocyclic Reactions) 在光或电的作用下，共轭烯烃转变为环烯烃或它的逆反应——环烯烃开环变为共轭烯烃的反应都称为电环化反应

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

he Greek word stereos means\solid, \and stereochemistry refers to chemistry in three dimensions. The foundations of organic stereochemistry were laid by Jacobus van't Hoff* and Joseph Achille Le Bel in 1874. Independently of each other, van't Hoff and Le Bel proposed that the four bonds to carbon were directed toward the cor- ners of a tetrahedron. One consequence of a tetrahedral arrangement of bonds to carbon

醚，可以看成是水分子中的两个氢原子被烃基取代而生成的化合物。分为简单醚(两个烃基相同，R-O-R)、混合醚(两个烃基不同，R-O-R’)

1. 核磁共振的基本原理 （1）原子核的自旋 原子核的自旋量子数：I 或ms 表示原子核的自旋运动情况。ms 与原子的质量数和原子序数之间的关系：

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

ntil the second half of the twentieth century, the structure of a substance-a newly discovered natural product, for example-was determined using information obtained from chemical reactions. This information included the identification of functional groups by chemical tests, along with the results of experiments in which the substance was broken down into smaller, more readily identifiable fragments. Typical of this approach is the demonstration of the presence of a double bond in an alkene by cat- nd subsequent