Reactions of Alkyl Halides

You may use these summaries and problems but you may NOT download them for use at another site, nor may you charge for access to them. Copyright Linda M. Sweeting 1997

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Nucleophilic Substitution


Mechanism! Stereospecific SN2 reaction.
Will be SN1 for tertiary halides (carboations, rearrangements)
Competition also from E2 elimination in non-aqueous solvents
McMurry 11.10, 16.8, Fessenden 5.4, 5.5, 5.10, Schmid 12.1, 12.2,

Mechanism! SN2 reaction.
Note that more substituted halides will undergo the E2 elimination instead.
McMurry 11.14, 11.15, 18.3, Fessenden 5.3, 8.2, Schmid 13.8C,

Mechanism! SN2 reaction.
McMurry 11.21, 24.6, Fessenden 5.4, 5.10, Schmid 12.2 - 12.4,

McMurry 8.8, 8.9, 8.10, Schmid 9.10 ,


The reaction is hard to control, because the products are at least as reactive; it works well for making amino acids from halo acids because the product is the conjugate acid of the amine (the carboxylic acid protonates it)
Mechanism!
McMurry 24.6, Fessenden 5.10, 18.4, Schmid 22.8,




The Wittig reaction; works best with less substituted halides, aldehydes and ketones.
McMurry 19.12, Fessenden 13.5, Schmid 14.16, 14.17,

Elimination: Dehydrohalogenation


Mechanism! E2, Stereospecific, but may be E1 in polar solvents
McMurry 11.10, 11.13, 11.15, Fessenden 5.7, 5.8, Schmid 12.12 - 12.15 ,

With Metals (Reduction)


The Grignard reagent
McMurry 10.8, 10.10, 17.6, Fessenden 7.3D, Schmid 11.7,
2
Note that aryl halides do not undergo any of these reactions except those with metals, e.g. the Grignard reaction. Nucleophilic aromatic substitution only occurs on rings with strongly electron-withdrawing substituents (Schmid 23.2, 23.3, Mc Murry 10.9).

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Last update Feb 10, 1999