PCAT Chemical Processes – Proton Acidity on Organic Molecules
- Apr 19, 2018
- PCAT Question of the Day
The acidity of a given proton on a molecule decreases as the strength of the covalent bond connecting that hydrogen to the rest of the molecule increases. With this information, which of the following ethanol derivatives has the most acidic proton?
Click for Explanation
D is correct. Due to the inductive effect, some of the electron density that comprises the bond between hydrogen and oxygen is drawn toward the electronegative fluorine atoms, away from the carbon chain. This weakens the hydrogen-oxygen bond and increases the acidity of the hydrogen atom. This electron-withdrawing effect also stabilizes the conjugate base, making it more favorable for the proton to leave. This effect is stronger in 2,2,2-trifluoroethanol than in the chlorinated and brominated derivatives because fluorine is more electronegative than chlorine or bromine.
Search the Blog
Free ConsultationSchedule Now
MCAT Blog How to Review MCAT Full-Lengths
Free MCAT Practice AccountNeed great MCAT practice?
Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.Learn More