Question

Account for the fact that tetrahydrofuran (THF) is very soluble in water, whereas the solubility of diethyl either in water is only \(8 \mathrm{~g} / 100 \mathrm{~mL}\) water.

Short answer

Based on the analysis of their molecular structures and solubility properties, the key difference between the solubility of tetrahydrofuran (THF) and diethyl ether in water can be attributed to their ability to form hydrogen bonds and overall polarity. THF, with a more polar structure and greater capacity for hydrogen bonding, is more soluble in water than diethyl ether, which has a less polar structure and weaker interactions with water molecules.

Step-by-step solution

Molecular structure of THF and diethyl ether

First, let's examine the molecular structures of tetrahydrofuran (THF) and diethyl ether. THF is a heterocyclic compound with the formula \(\mathrm{C_4H_8O}\), containing an oxygen atom within a five-membered ring. Diethyl ether, on the other hand, is an ether compound with the formula \(\mathrm{C_4H_{10}O}\), in which there is also an oxygen atom, but it is not part of a ring structure. The molecular structure has a significant effect on their solubility in water.

Hydrogen bonding, polarity, and solubility

Water is a polar molecule, meaning that it has regions of positive and negative charge. In addition, it has the ability to form hydrogen bonds as it contains hydrogen atoms bonded to oxygen atoms. Due to these properties, water can dissolve polar molecules as well as compounds that can form hydrogen bonds. In the case of THF, the oxygen atom within the ring structure is able to engage in hydrogen bonding with water molecules, leading to its high solubility in water. On the other hand, diethyl ether contains an oxygen atom, but its overall structure is less polar, and it does not possess strong hydrogen bonding capabilities as observed in THF.

Like dissolves like principle

An important principle for solubility is "like dissolves like." This principle states that polar molecules can dissolve other polar molecules while nonpolar molecules can dissolve nonpolar molecules. Therefore, since water is a polar molecule and capable of hydrogen bonding, it can dissolve polar compounds like THF more easily than nonpolar or weakly polar compounds like diethyl ether.

Solubility differences of THF and diethyl ether in water

In conclusion, the solubility differences between tetrahydrofuran (THF) and diethyl ether in water can be attributed to their molecular structures and ability to form hydrogen bonds. THF, with its higher polarity and greater capacity for hydrogen bonding, is much more soluble in water than diethyl ether, which has comparatively weaker interactions with water molecules due to its less polar structure.