The (R)-enantiomer of the antiasthma drug albuterol is the active isomer. If a researcher wants to separate a racemic mixture of albuterol, which of the following methods will most likely separate the enantiomers?

Question

The (R)-enantiomer of the antiasthma drug albuterol is the active isomer.  If a researcher wants to separate a racemic mixture of albuterol, which of the following methods will most likely separate the enantiomers?

Quizplus · Accepted Answer

11ecba2d_1278_96bc_a3bf_1570b3aaf3e5_MD0008_00 An atom bonded to four unique substituents is called a chiral center. If corresponding chiral centers in a pair of otherwise identical molecules have the opposite configuration (ie, R in one molecule, S in another), the molecules are known as enantiomers, or nonsuperimposable mirror images. A 50:50 mixture of enantiomers is known as a racemic mixture. Enantiomers have many of the same chemical and physical properties, including melting and boiling points, solubility, and polarity, although they differ in the way that they interact with plane-polarized (linear) light. Therefore, separation of enantiomers relies on changing the physical properties of the molecules. The separation of enantiomers, such as those in the racemic mixture of albuterol, requires the addition of a resolving agent (a chiral molecule). When a resolving agent is added to a racemic mixture, it reacts with each enantiomer, forming a covalent bond or an ionic salt. Because the resolving agent is chiral, it incorporates a new chiral center into each enantiomer, creating a pair of diastereomers. Diastereomers can be separated from each other because, unlike enantiomers, they have different physical properties. Once the diastereomers are separated, the resolving agent is removed, yielding the original molecules as single enantiomers. (Choices A, B, and C) Because enantiomers have the same chemical and physical properties, they cannot be separated by physical means such as extraction, thin-layer chromatography (TLC), or fractional distillation. Enantiomers react in the same way with bases, have the same retention time on a TLC plate, and have the same boiling point. Educational objective: A racemic mixture is a 50:50 mixture of enantiomers, which have the same chemical and physical properties, and therefore cannot be directly separated. Consequently, the separation of enantiomers requires the addition of a resolving agent to change their physical properties by creating a pair of diastereomers. The resolving agent is removed once the diastereomers are separated to yield the original molecules as single enantiomers .

The (R)-Enantiomer of the Antiasthma Drug Albuterol Is the Active