Functional Groups
Reactivity patterns of alcohols, aldehydes, ketones, carboxylic acids, amines, and esters. How functional group identity determines chemical behavior, acidity, basicity, and reaction pathways in organic chemistry.
Ethanol (pKa ~16) is far too weak an acid to react appreciably with NaOH under normal conditions. You would need a much stronger base, such as sodium metal or sodium hydride, to deprotonate an alcohol.
Carboxylic acids react readily with NaOH through a straightforward acid-base neutralization. Acetic acid (pKa 4.76) is acidic enough to donate a proton to the strong base hydroxide, forming sodium acetate and water.
Ketones are less reactive toward nucleophilic addition because the two alkyl groups create steric crowding around the carbonyl carbon. Additionally, the two electron-donating alkyl groups partially reduce the positive character of the carbonyl carbon.
Aldehydes are more susceptible to nucleophilic addition than ketones for two reasons. First, the carbonyl carbon has less steric hindrance with only one alkyl substituent. Second, the single alkyl group donates less electron density to the carbonyl carbon, keeping it more electrophilic.
Amides are extremely weak bases (pKb ~14) because the nitrogen lone pair is delocalized into the adjacent carbonyl group through resonance. This resonance stabilization makes the lone pair far less available for protonation.
Primary amines are much more basic than amides. In methylamine, the nitrogen lone pair is freely available to accept a proton. The pKb of 3.36 makes methylamine a moderately strong base.