Amines-Notes

Amines are a class of organic nitrogen compound.

They smell "fishy" (butylamine is gross).

Amines are used for...

• Making dyes
• Making medicines
• Making detergents (quaternary ammonium salts are used to make cationic surfactants)

You can get primary, secondary and tertiary amines as well as quaternary ammonium ions.

Like primary, secondary and tertiary alcohols, the class of amine is determined by the number of alkyl/aryl groups attatched to the nitrogen atom:

• Primary amines have one group bonded to the nitrogen atom
• Secondary amines have two groups bonded to the nitrogen atom
• Tertiary amines have three groups bonded to the nitrogen atom
• Quaternary ammonium ions have four groups attached to the nitrogen atom making it electron defficient and leaving it with a positive charge. They can often be salts which are crystalline and soluble in water.

Small amines are soluble in water and primary/secondary amines form hydrogen bonds with one another too because of the lone electron pair on the nitrogen and its attraction to partially positive hydrogen atoms:

Amines act as weak bases. 

The amine is a base because it is a proton acceptor. The nitrogen donates its lone pair of electrons to the proton from the acid forming a dative covalent bond.

In solution, this equilibrium is formed:

RNH2 + H2O RNH3+ + OH-

Because amines are weak bases, this equilibrium lies far to the left.

Amines will react in a typical acid-base reaction if mixed with an acid, forming a salt:

CH3CH2NH2 + HCl → CH3CH2NH2H+Cl-

You can see that the entire acid molecule goes "into" the amine.

The salt formed is ethylammonium chloride--an ammonium salt containing chlorine and an ethyl group (CH3CH2).

Three factors affect the basicity of an amine:

• How available the electron pair on the nitrogen is for…