Primary amines are primary amines, and amines are hydrocarbon derivatives. According to the number of hydrocarbon groups connected to the nitrogen atom in the amine, they can be divided into primary amines, secondary amines and tertiary amines. If connected with 4 hydrocarbon groups, it is quaternary ammonium compound.
Amines are organic compounds in which the hydrogen atoms of ammonia are replaced by hydrocarbon groups. Amines are widely present in the biological world and have extremely important physiological roles. Generally, primary amines can be divided into aliphatic primary amines and aromatic primary amine according to the difference of the hydrocarbon groups connected to the nitrogen atoms. Primary amines are weakly basic, aliphatic primary amines are more basic than ammonia, and aromatic primary amines are generally less basic than aliphatic primary amines.
The reaction of ammonia and halogenated hydrocarbons is also called amination reaction, which belongs to the nucleophilic substitution reaction of halogenated hydrocarbons. The resulting product is a mixture of primary amine, secondary amine, tertiary amine and quaternary ammonium salt. The yields of primary amines are high, while the yields of secondary and tertiary amines increase when ammonia is insufficient.
(1) The general formula is different
①Primary amine: RNH2.
②Secondary amine: R2NH.
③ Tertiary amine: R3N.
(2) The number of hydrocarbon groups attached to the nitrogen atom is different
①Primary amine: connect one hydrocarbon group.
②Secondary amine: connect two hydrocarbon groups.
③ Tertiary amine: connect 3 hydrocarbon groups.
(3) Differences in characteristics and properties
①Primary amine: The nitrogen atom in the primary amine has strong nucleophilicity and is the main method for synthesizing organic amines.
②Secondary amine: It is the synthon of many natural products and biologically active molecules, and it is also the key active functional group of modern medicine.
③Tertiary amine: It has a wide range of uses. It can be used as a component of formulated products, as an intermediate product of various special chemical derivatives, and as an important raw material for the production of quaternary ammonium salts.
2. How to distinguish primary, secondary and tertiary amines
(1) Nitrous acid reagent: The diazonium salt formed by the reaction of primary amine and nitrous acid dissolves in water and is a colorless solution, while the secondary amine produces a yellow oily substance, and the tertiary amine does not react.
(2) Sulfonyl chloride: The primary amine reacts with sulfuryl chloride to form a precipitate and dissolve immediately, the secondary amine precipitates but does not dissolve, and the tertiary amine does not react.