Organic Chemistry MCAT Practice Exam

What is the result of adding a strong acid when extracting an amine?

1. It converts the amine into a salt

2. It deprotonates the amine

3. It enhances its polarity

4. It vaporizes the amine

The correct answer is: It converts the amine into a salt

When a strong acid is added during the extraction of an amine, the primary outcome is the conversion of the amine into a salt. This occurs because amines, which are basic due to their lone pair of electrons on the nitrogen atom, react with strong acids to form ammonium salts. The proton from the acid attaches to the nitrogen atom of the amine, resulting in the formation of a positively charged ammonium ion. This conversion into a salt significantly increases the solubility of the amine in aqueous solutions, thereby facilitating its separation from non-polar solvents. The resulting ammonium salt is generally more polar than the original amine, which can be advantageous for the extraction process. While the increase in polarity is somewhat related, it is a consequence of the formation of the salt rather than a direct result of the acid addition itself. The amine does not get deprotonated by adding a strong acid; instead, it gets protonated. Further, the addition of a strong acid does not vaporize the amine but rather alters its chemical state by forming a soluble salt. This understanding of the acid-base chemistry involved in the extraction process is crucial for effectively isolating amines in organic chemistry.