Basic information and introduction to primary amines

Amine is a hydrocarbyl derivative of ammonia. According to the number of hydrocarbyl groups connected to the nitrogen atom in the amine, it can be divided into primary amine, secondary amine, and tertiary amine. If connected with four hydrocarbyl groups, it is a quaternary ammonium compound, in which the number of hydrocarbyl groups is 1 One is a primary amine. According to the number of amino groups in the primary amine, it can be divided into monoamine, diamine and polyamine. According to the difference of the hydrocarbon group attached to the nitrogen atom, it can be divided into aliphatic primary amine and aromatic primary amine. 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. Primary amines are a class of active compounds. Due to the unshared electron pair on the nitrogen atom, they can be used as nucleophiles to participate in many reactions, such as alkylation, acylation, sulfonylation, reaction with carbonyl compounds, and oxidation reactions. , and can also react with nitrous acid to generate various compounds.
There are many preparation methods for primary amines, such as the reduction of nitro compounds, amides, and nitriles; the amination reduction of carbonyl compounds; the alkylation of ammonia or amines; synthesis through rearrangement reactions, etc.
Nitrogen atoms in primary amines have strong nucleophilicity, and the hydrocarbylation on nitrogen is much easier than that on oxygen, which is the main method for synthesizing organic amines. Commonly used hydrocarbylation reagents are halogenated hydrocarbons, alcohols, alkyl sulfates, alkylene oxides, aromatic sulfonates, and the like.
Hydrocarbylation of Ammonia
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, secondary and tertiary amine quaternary ammonium salts. Yields of secondary and tertiary amines increased.
Hydrocarbylation of Primary Amines
The reaction of primary amines with halogenated hydrocarbons mainly produces a mixture of secondary and tertiary amines, and the structure of the reactants has a certain influence on the resulting products. Generally speaking, when haloalkanes have high activity, primary amines have strong basicity, and there is no obvious steric hindrance between the two, mixed amines are often obtained, and the proportion of products depends on conditions such as raw material ratio and reaction temperature. If the halide is active and the primary amine is strong, and one of the two has steric hindrance, or if the halide is active and the primary amine is weak, and the two have no steric hindrance, the yield of the secondary amine is high.

 

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