Reaction Mechanism

Reaction Mechanism Alkylhalide reactivity

Outline Synthesis  Chemical Properties of Alkyl Halide  Nucleophilic substitution  Elimination 

Synthesis 

Among the “building block” molecules used as starting materials to prepare new substances, alcohols and alkyl halides are especially valuable

Alcohol Substitution

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Secondary and primary alcohols do not react with hydrogen chloride at rates fast enough to make the preparation of the corresponding alkyl chlorides a method of practical value. Therefore, the more reactive hydrogen halide HBr is used; even then, elevated temperatures are required in order to increase the rate of reaction.

Halogenation of Alkane

Chemical Properties

Nucleophlilic Substitution Nucleophilic substitution reactions of alkyl halides are related to elimination reactions in that the halogen acts as a leaving group on carbon and is lost as an anion.  The carbon–halogen bond of the alkyl halide is broken heterolytically: the pair of electrons in that bond are lost with the leaving group. 

SN2 Mechanism

SN1 Mechanism

Elimination

Elimination vs Substitution