Pharmaceutical Chemistry Flashcards

Which chemical reaction is used in the synthesis of esters from carboxylic acids?

Answer: Fischer esterification

Fischer esterification involves the acid-catalyzed condensation of a carboxylic acid with an alcohol to form an ester and water.

The term 'bioisostere' in medicinal chemistry refers to:

Answer: A substituent or group that produces similar biological effects to another group

Bioisosteres are atoms or groups that produce broadly similar biological activity due to similar size, electronegativity, or electronic effects.

Which oxidation state characterizes a sulfonic acid group (-SO3H)?

Answer: +6

In a sulfonic acid (-SO3H), sulfur has an oxidation state of +6, the same as in sulfuric acid H2SO4.

In pharmacokinetics, the concept of 'ionization trapping' in the stomach means that:

Answer: Basic drugs are trapped in the stomach because ionization reduces membrane permeability

Basic drugs become protonated (ionized) in the acidic stomach environment, making them water-soluble but membrane-impermeable, trapping them in the gastric lumen.

Which reaction converts a primary amine to a diazonium salt?

Answer: Diazotization (with NaNO2/HCl)

Diazotization reacts a primary aromatic amine with sodium nitrite (NaNO2) in acidic (HCl) conditions at 0–5°C to form a diazonium salt (ArN2+Cl-).

Hydrolysis of an amide bond under acidic conditions produces:

Answer: A carboxylic acid and an amine (or ammonium salt)

Acid hydrolysis of an amide cleaves the C-N bond, yielding a carboxylic acid and the protonated amine (ammonium salt).

Which analytical technique is most commonly used to confirm the identity and purity of a crystalline drug substance by its unique molecular fingerprint?

Answer: Infrared (IR) spectroscopy

IR spectroscopy identifies functional groups and provides a molecular fingerprint region (1500–400 cm⁻¹) unique to each compound, used for identity confirmation.