Background for Amines
Amines are classified by the number of carbons directly attached to the nitrogen. A primary amine contains one alkyl group attached to the nitrogen. A secondary amine contains two alkyl groups attached to the nitrogen. A tertiary amine contains three alkyl groups attached to the nitrogen. A quaternary amine contains four alkyl groups attached to the nitrogen. Primary, secondary, and tertiary amines are sp3 hybridized, have a trigonal pyramidal shape, and a bond angle of 107o. Quaternary amines are sp3 hybridized, have a tetrahedral shape, and a bond angle of 109.5o. Primary and secondary amines have intermolecular hydrogen bonding. Primary and secondary amines have boiling points and melting points between ethers and alcohols. Tertiary amines have boiling points and melting points lower than primary and secondary amines with similar molecular weights. Amines have fishy smells.
IUPAC Nomenclature for Amines
For the IUPAC nomenclature, the longest continuous carbon chain is the parent compound. Number the chain so that the C-N bond has the lowest possible number. From the alkyl prefixes, use Aanamine@ for amines. Give the location of the attachment of the N to the parent amine. Name and number substituents.
Common Nomenclature for Amines
For the common nomenclature, an amine is named with the alkyl groups first, then Aamine.@ Alphabetize the groups. Name amine salts as ammonium salts.
Synthesis of Amines
Nitro compounds are reduced to primary amines with hydrogen with a catalyst (nickel, palladium, or platinum). Nitro compounds are reduced to primary amines with acid and a metal (iron, zinc, or tin). Nitriles are reduced to primary amines with hydrogen and nickel. Amides are reduced with lithium aluminum hydride, followed by hydrolysis, to amines. Alkyl halides react with ammonia or amines, followed by loss of hydrogen halide, to yield amines. Aldehydes and ketones react with hydroxylamine, followed by reductive amination, to form primary amines. Possible reduction reagents are hydrogen and nickel; lithium aluminum hydride and hydrolysis; and zinc and hydrochloric acid. Aldehydes and ketones react with primary amines, followed by reductive amination, to form secondary amines. Reduction reagents include hydrogen and nickel or lithium aluminum hydride, followed by hydronium ion. Aldehydes and ketones react with secondary amines, followed by reductive amination with sodium triacetoxyborohydride, to yield tertiary amines
Reactions of Amines
Amines react with hydrogen halides to form ammonium salts. Aldehydes and ketones react with ammonia derivatives, in the presence of acid, to form imine derivatives. Acid chlorides react with amines to form amides. Sulfonyl chlorides react with amines to yield sulfonamides.