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

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

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

ot all the properties of alkenes are revealed by focusing exclusively on the func- tional group behavior of the double bond. A double bond can affect the proper- ties of a second functional unit to which it is directly attached. It can be a sub- stituent, for example, on a positively charged carbon in an allylic carbocation, or on a carbon that bears an unpaired electron in an allylic free radical, or it can

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

rganometallic compounds are compounds that have a carbon-metal bond; they lie at the place where organic and inorganic chemistry meet. You are already familiar with at least one organometallic compound, sodium acetylide (NaC=CH), which has an ionic bond between carbon and sodium. But just because a compound contains both a metal and carbon isn't enough to classify it as organometal-

the preceding chapter you learned that nucleophilic addition to the carbonyl group is one of the fundamental reaction types of organic chemistry. In addition to its own reactivity, a carbonyl group can affect the chemical properties of aldehydes and ketones in other ways. Aldehydes and ketones are in equilibrium with their enol isomers

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

itrogen-containing compounds are essential to life. Their ultimate source is atmo- spheric nitrogen which, by a process known as nitroge. nitrogen fixation, is reduce ced to ammonia, then converted to organic nitrogen compounds. This chapter describes the chemistry of amines, organic derivatives of ammonia. Alkylamines have their nitro- gen attached to sp'-hybridized carbon; arylamines have their nitrogen attached to an sp2-hybridized carbon of a benzene or benzene-like ring

ipids differ from the other classes of naturally occurring biomolecules (carbohy- drates, proteins, and nucleic acids)in that they are more soluble in non-to-weakly polar solvents(diethyl ether, hexane, dichloromethathan they are in water.they include a variety of structural types, a collection of which is introduced in this chapter. In spite of the number of different structural types, lipids share a common biosyn- thetic origin in that they are ultimately derived from glucose. During one stage of car- bohydrate metabolism, called glycolysis, glucose is converted to lactic acid. Pyruvic acid is an intermediate