氨酸及其相应的氨基基碳酸盐的温度依赖结构及其相应的氨基基碳酸盐的温度依赖结构

Amines can behave as Brønsted–Lowry bases by accepting a proton from the acid to form corresponding conjugate acids. Due to a lone pair of nonbonding electrons, aliphatic amines can also act as Lewis bases by forming a covalent bond with an electrophile.
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates higher...

The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...

Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...

Amines with low molecular weight are usually gaseous at room temperature, while those with high molecular weight are liquid or solids in nature. Usually, low molecular weight amines have a rotten fish-like smell. Diamines typically have a pungent smell. For instance, cadaverine and putrescine, depicted in Figure 1, are two molecules responsible for decaying tissue.

Enamine formation involves the addition of carbonyl compounds to a secondary amine through a series of reactions. The mechanism begins with the generation of carbinolamine, a nucleophilic attack followed by several proton transfer reactions. The hydroxyl group of the carbinolamine is converted into water to make a better leaving group that can push the reaction forward by eliminating a water molecule. In enamine formation, the last step involves the abstraction of a proton from the α carbon to...

Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.