Monoalkylamines with short chain radicals are gases, Monoalkylamines with medium length radicals are liquids.

All amines have a characteristic odour, which in many alkylamines is reminiscent of ammonia.
The intensity of the odour is severe for low molecular weights, but decreases as the molecular weight increases.

The dissolving properties follow a similar pattern: short chain alkylamines are freely soluble in water and the common organic solvents such as ethanol and ether.
As the molecular weight and the degree of substitution increases, the solubility in water decreases.

Most aliphatic di- amines are faintly coloured, slightly viscous liquids that are freely soluble in water and have an intense ammonia-like odour. They have almost unlimited miscibility with methanol, acetone, toluene, and ether, but are only sparingly soluble in aliphatic hydrocarbons.