Haloalkanes characteristic reactions

In this chapter, we study two characteristic reactions of haloalkanes nucleophilic substitution and /3-elimination. Haloalkanes are useful molecules because they can be converted to alcohols, ethers, thiols, amines, and alkenes and are thus versatile molecules. Indeed, haloalkanes are often used as starting materials for the synthesis of many useful compounds encountered in medicine, food chemistry, and agriculture (to name a few). 

In Chapters 11 and 12 we return to the presentation of a new functional group the carbon-carbon double bond. This functional group differs from those seen so far in that it hicks strongly polarized covalent bonds. Instead, its reactivity arises from specitil characteristics of electrons in so-called it bonds. The properties of the.se electrons and their consequences are discussed in the next chapter. Chapter 11 is restricted to a general description of alkenes as a compound class and a presentation of methods of preparation of double bonds. Most of the reactions are ones you have already seen, because the major methods of alkene syntheses are the same elimination reactions of alcohols and haloalkanes that were presented in Chapters 7 and 9. Only some finer details have been added. 

Certain nucleophilic displacements that have the kinetic characteristic of Sj l reactions (first order in haloalkane and zero order in nucleophile) involve two successive Sj 2 reactions. 

In the second group we consider interconversions of functional groups with the exchange of hetereoatoms, breaking of old and formation of new C-heteroatom bonds. Examples of these transformations are interconversion of an amide to ester, thioketone to ketone or alkylhalide to alcohol. They are related to S5mthetic reactions formation of amide from ester, thioketone from ketone or haloalkane from alcohol. Characteristic of all the above interconversions is the disconnection (imaginative process ) of the C-heteroatom bond, C-N or C-O. In the synthetic direction C-N, C-S and C-Hal bonds are formed. Therefore, such FGIs are also denoted as DIS-C-X, where X stands for heteroatom. 

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