Lower aliphatic amines are soluble in water due to the ability to form hydrogen bonds with water molecules. However, solubility decreases with increasing molar mass of amines because of the larger hydrophobic alkyl part.
Why do lower aliphatic amines exhibit higher solubility in water compared to higher amines, and what factor influences this solubility?
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Lower aliphatic amines, such as methylamine and ethylamine, exhibit higher solubility in water compared to higher amines due to the presence of hydrogen bonding. Lower amines can form hydrogen bonds with water molecules more effectively as they have smaller and more polarizable molecules. The primary factor influencing this solubility is the ability of the amine molecules to engage in hydrogen bonding with water. In contrast, higher aliphatic amines have larger hydrophobic alkyl groups, reducing their capacity for hydrogen bonding, resulting in lower water solubility compared to their smaller counterparts.