Final answer:
β-carotene's nonpolar structure, composed of two β-ionone rings connected by a hydrocarbon chain, makes it much more soluble in nonpolar solvents like petroleum ether than in polar solvents like water. Its solubility is explained by the principle that 'like dissolves like.'
Step-by-step explanation:
β-carotene is significantly more soluble in petroleum ether than in water because of its chemical structure, which heavily influences its solubility. β-carotene, consisting of two β-ionone rings connected by an eighteen-member hydrocarbon chain, with sporadic methyl group substitutions, exhibits strong nonpolar characteristics. Since petroleum ether is a nonpolar solvent, it can effectively dissolve β-carotene due to the 'like dissolves like' principle in chemistry, where nonpolar solutes are more soluble in nonpolar solvents.
On the other hand, water is a polar solvent, and due to β-carotene's nonpolar nature, it has low solubility in water. β-carotene's extended system of 11 conjugated double bonds also contributes to its nonpolarity. This is similar to other lipid soluble vitamins such as Vitamins A, E, and K, which also exhibit lipophilic (fat-loving) properties due to their complex nonpolar structures.
Understanding the molecular structure and solubility behavior of compounds such as β-carotene can also extend to understanding properties of other organic substances, such as why haloalkanes dissolve in organic solvents but are only slightly soluble in water, or why the hydrogenation of vegetable oils affects their physical properties like melting points.