Which of the following molecular structures has the most hydrophobic character?

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11ecba2d_1236_f984_a3bf_f7c505671f5d_MD0008_00 In the structure of a water molecule, the large electronegativity difference between the covalently bonded H and O atoms produces a polar covalent bond in which the H atom has a partial positive charge and the O atom has a partial negative charge. The partial charges associated with the dipole of the O-H bonds cause water to readily interact with polar bonds or ionic charges in other molecules via ion-dipole interactions, dipole-dipole interactions, or hydrogen bonding (strong dipolar interactions from bonds involving H, N, O, and F). Molecules with many polar bonds that promote dipolar interactions with water are hydrophilic ("water-loving"), whereas those with mostly nonpolar bonds that lack attractive dipolar interactions with water are hydrophobic ("water-fearing"). Frequently, a compound structure will have both nonpolar and polar bonds that make a strict binary classification difficult. In such cases, the overall hydrophobic or hydrophilic character of the compound depends on the relative number of each type of bond and the strength of the dipoles present. The compounds presented in this question each consist of a five-carbon chain and differ in the number of polar bonds and nonpolar methyl substituents. Among the four structures, the compound with the greatest number of nonpolar methyl (-CH₃) groups and the fewest polar bonds (Choice D) will interact with polar water molecules the least and have the most hydrophobic character. (Choice A) This structure is very hydrophilic due to having one very polar O-H bond, two very polar N-H bonds, and one polar C-F bond, which are all capable of hydrogen bonding. The structure contains only two nonpolar methyl groups. (Choices B and C) These structures have an intermediate hydrophobic character due to having fewer polar bonds, but neither compound has the most hydrophobic character among the answer choices. Each has only three nonpolar methyl groups. Educational objective: Molecules with many polar bonds that promote dipolar interactions with water are hydrophilic, whereas those with mostly nonpolar bonds that lack attractive dipolar interactions with water are hydrophobic. The overall character of a compound depends on the relative number of each type of bond present.

Which of the Following Molecular Structures Has the Most Hydrophobic