Alkyl Halides Nucleophilic Substitution and Elimination

Our study of organic chemisti is organized into families of compounds classified by their f unctional groups. In this chapter, we consider the properties and reactions of alkyl halides. We use their reactions to introduce substitution and elimination, two of the most important types of reactions in organic chemistry. Stereochemistry (Chapter 5) will play a major role in our study of these reactions. Many other reactions show similarities to substitution and elimination, and the techniques introduced in this chapter will be used throughout our study of organic reactions. 

There are three major classes of organohalogen compounds the alkyl halides, the vinyl halides, and the aryl halides. An alkyl halide simply has a halogen atom bonded to one of the sp hybrid carbon atoms of an alkyl group. A vinyl halide has a halogen atom bonded to one of the sp hybrid carbon atoms of an alkene. An aryl halide has a halogen atom bonded to one of the sp hybrid carbon atoms of an aromatic ring. The chemistry of vinyl halides and aryl halides is different from that of alkyl halides because their bonding and hybridization are different. We consider the reactions of vinyl halides and aryl halides in later chapters. The structures of some rqjresentative alkyl halides, vinyl halides, and aryl halides are shown here, with their most common names and uses. 

Chloromethane and its electrostatic potential map (EPM). The polar C—Cl bond is seen in the EPM as an electron-rich (red) region around chlorine and an electron-pOOr (blue) region around carbon and the hydrogen atoms. 

Classify each compound as an alkyl halide, a vinyl halide, or an aryl halide. 

There are two ways of naming alkyl halides. The systematic (lUPAC) nomenclature treats an alkyl halide as an alkane with a halo- substituent Fluorine is jluoro-, chlorine is chloro-, bromine is bromo-, and iodine is iodo-. The result is a systematic haloalkane name, as in 1-chlorobutane or 2-bromopropane. Common or trivial names are constructed by naming the alkyl group and then the halide, as in isopropyl bromide. This is the origin of the term alkyl halide. Common names are useful only for simple alkyl halides, such as the following  

6-1 In problems like part (a), draw out the whole structure to detect double bonds. 

6-3 lUPAC name common name degree of halogen-bearing carbon 

6-7 From Table 3-2, the density of hexane is 0.66 it will float on the water layer (d 1.00). From Table 6-2, the density of chloroform is 1.50 water will float on the chloroform. Water is immiscible with many organic compounds whether water is the top layer or bottom layer depends on whether the other material is more dense or less dense than water. (This is an important consideration to remember in lab procedures.) 

This is a very exothermic reaction it is reasonable to expect a small activation energy in step (1), so this reaction should be very rapid. 

The resonance-stabilized allylic radical intermediate has radical character on both the 1° and 3° carbons, so bromine can bond to either of these carbons producing two isomeric products. 

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CHAPTER 11 Reactions of Alkyl Halides Nucleophilic Substitutions and Eliminations... 

Chapter 11, Reactions of Alkyl Halides Nucleophilic Substitutions and Eliminations—A discussion of the El cB reaction has been added to Section 11.10, and a new Section 11.11 discusses biological elimination reactions. 

CHAPTER 6 Alkyl Halides Nucleophilic Substitution and Elimination... 

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