Question

Which of the following functional group modifications for the clinically used drug would likely increase water solubility?

a) Adding a methyl group (-CH3) to the existing structure

b) Introducing a hydroxyl group (-OH) to the existing structure

c) Substituting a benzene ring for an alkane chain

d) Removing a carboxyl group (-COOH) from the existing structure

Answer 1

Adding a hydroxyl group (-OH) to a drug's structure is most likely to increase its water solubility due to the group's polar, hydrophilic nature, which allows it to form hydrogen bonds with water(option b).

Step-by-step explanation:

The modification of a functional group in a drug affects its water solubility. Adding a hydroxyl group (-OH) to the existing structure of a drug will likely increase its water solubility because a hydroxyl group can engage in hydrogen bonding with water. This is based on the principle that 'like dissolves like', where polar groups (like -OH) are hydrophilic and attracted to water, thus increasing solubility.

Hence, the correct answer is option b i.e. Introducing a hydroxyl group (-OH) to the existing structure.