Alkyl and Aryl Halides - Nucleophilic substitution reactions

Nucleophilic substitution in primary halogenoalkanes
The nucleophilic substitution reaction - an SN2 reaction - S stands for substitution, N for nucleophilic, and the 2 is order of reaction. It is because the initial stage of the reaction involves two species - the bromoethane and the Nucleophilic (Nu-) ion.



Nucleophilic substitution in tertiary halogenoalkanes - The nucleophilic substitution reaction - an SN1 reaction (1 denotes 1st order)



Many organic compounds are prepared using alkyl halides

Nucleophilic substitution reactions

1. Substitution by hydroxylgroup (OH) leads to the formation of alcohols
2. Substitution by alkoxy group leads to the formation of ether.
3. Substitution by cyano group leads to the formation of cyanides or nitriles.

4. Substitution by isocyanide group leads to the formation of isocyanides.
When haloalkane is treated with alcoholic silver cyanide (AgCN), isocynaides (R-N≡C) are obtained. They are also called carbyl amines.

RX + AgCN ---> RNC + AGX

C2H5Br + AgCN ---> C2H5NC + Ag Br

5. Substitution by amino group leads to the formation of amines.
6. Substitution by nitrite group leads to the formation of nitrite.
7. Substitution by nitro group leads to the formation of nitro alkanes.
8. Substitution by carboxyl group leads to the formation of esters.
9. substitution by hydrosulphide group leads to the formation of thioalcohols.
10. Substitution by mercaptide group leads to the formation of thioethers.
11. Substitution by alkyl group leads to the formation of alkynes.