Reactions of Alkyl Halides Nucleophilic Substitution and Eliminations

Nucleophilic substitution reactions of primary and secondary alkyl halides always proceed with inversion of configuration. 

This type of reaction is a second-order reaction. 

This type of attack accounts for inversion of configuration. 

Poor leaving groups can be converted to better leaving groups. 

These reactions must be occurring by a different mechanism. 

Reactions of Alkyl Halides Nucleophilic Substitutions and Eliminations 

We saw in the preceding chapter that the carbon-halogen bond in alkyl halides is polar and that the carbon atom is electron-poor. Thus, alkyl halides are electrophiles, and much of their chemistry involves polar reactions with nucleophiles and bases. 

Alkyl halides do one of two things when they react with a nuclei] phile/base Either they undergo substitution of the X group by the nuclei phile (Nu), or they undergo elimination of HX to yield an alkene  

These two reactions—nucleophilic substitution and base-induced elimina tion—are two of the most widely occurring and versatile reactions in organ chemistry. We ll take a close look at both in this chapter to see how the occur, what their characteristics are, and bow they can be used to synthesize new molecules. 

In 1896, the German chemist Paul Walden made a remarkable discoveij 

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We saw in the preceding chapter that the carhon-halogen bond in an alky] halide is polar and that the carbon atom is electron-poor. Thus, alkyl halides are electrophiles, and much of their chemistry involves polar reactions with nucleophiles and bases. Alkyl halides do one of two things when they react with a nucleophile/base, such as hyd) oxide ion either they undergo subsiitution of the X group by the nucleophile, or they undergo eliminaiion of HX to yield an alkene. 

In 1896, the German chemist Paul Walden made a remarkable discovery. He found that the pure enantiomeric (- )- and (-)-malic acids could be intercon-veiTed through a series of simple substitution reactions. When W alden treated (-)-malic acid with PCI5, he isolated (-)-chlorosiicdmc acid. This, on treatment with wet Ag20, gave (+)-malic acid. Similarly, reaction of (-f )-malic acid with 

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Online homework for this chapter may be assigned in Organic OWL. 

The discovery of the nucleophilic substitution reaction of alkyl halides dates back to work carried out in 1896 by the German chemist Paul Walden. Walden 

we refer to the transformations taking place in Walden s cycle as nucleophilic substitution reactions because each step involves the substitution of one nucleophile (chloride ion, Cl , or hydroxide ion, HO ) by another. Nucleophilic substitution reactions are one of the most common and versatile reaction types in organic chemistry. 

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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. 

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