Fatty amine

Production and reactions

Fatty amines are commonly prepared from fatty acids; which are themselves obtained from natural sources, typically seed-oils. The overall reaction is sometimes referred to as the Nitrile Process and begins with a reaction between the fatty acid and ammonia at high temperature (>250 °C) and in the presence of a metal oxide catalyst (e.g., alumina or zinc oxide) to give the fatty nitrile.

RCOOH + NH₃ → RC≡N + 2 H₂O

The fatty amine is obtained from these fatty nitriles by hydrogenation with any of a number of reagents, including Raney nickel or cobalt, and copper chromite catalysts. When conducted in the presence of excess ammonia the hydrogenation affords the primary amines.

RCN + 2 H₂ → RCH₂NH₂

In the absence of ammonia, secondary and tertiary amines are produced.

2 RCN + 4 H₂ → (RCH₂)₂NH + NH₃

3 RCN + 6 H₂ → (RCH₂)₃N + 2 NH₃

Fatty secondary and tertiary amines

Alternatively, secondary and tertiary fatty amines can be generated by the reaction of fatty alcohols and fatty alkyl bromides with (di)alkylamines. For example 1-bromododecane reacts with dimethyl amine:

RBr + HNMe₂ → RNMe₂ + HBr

By reaction with tertiary amines, long-chain alkyl bromides give quaternary ammonium salts, which are used as phase transfer catalysts.

Secondary and tertiary amines may also be produced by the Leuckart reaction. This reaction effects N-methylation using formaldehyde with formic acid as the reductant. These tertiary amines are precursors to quaternary ammonium salts used for a variety of applications.