See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the type of each -OH group: - (w): Phenolic -OH directly attached to the aromatic benzene ring. Phenols are significantly more acidic than alcohols due to resonance stabilization of the phenoxide anion by the aromatic ring. - (x): Primary aliphatic alcohol (-CH2OH attached to the cyclohexane ring, not at a benzylic position directly). This is a primary alkyl alcohol. - (y): Secondary benzylic alcohol - the -OH is on a carbon adjacent to (or at the junction with) the aromatic ring (benzylic position on the cyclohexane ring). Benzylic alcohols are slightly more acidic than simple aliphatic alcohols due to weak resonance stabilization. - (z): Secondary aliphatic alcohol on the cyclohexane ring, away from the aromatic ring, non-benzylic. Step 2 - Rank acidic strength: - Phenol (w) is most acidic because the phenoxide anion is resonance-stabilized by delocalization into the aromatic ring (pKa ~10). - Primary alcohols (x) are slightly more acidic than secondary alcohols because primary carbons are less electron-donating (less inductive destabilization of the alkoxide), so (x) > (y) and (x) > (z). - Between (y) (secondary benzylic) and (z) (secondary non-benzylic aliphatic): benzylic position provides slight extra stabilization, so (y) > (z) might be expected, but note (y) is secondary benzylic and (z) is secondary aliphatic. However, the question states the answer is (a) w > x > y > z. - (y) benzylic secondary alcohol: the benzylic position gives slight resonance stabilization to the alkoxide, making it marginally more acidic than a plain secondary aliphatic alcohol (z). - Therefore the order is: w (phenol) > x (primary alkyl alcohol) > y (secondary benzylic alcohol) > z (secondary aliphatic alcohol). Step 3 - Why other options fail: - (b) w > z > x > y: Incorrectly places z above x and y, ignoring that primary alcohols are more acidic than secondary and that benzylic position adds acidity. - (c) z > w > x > y: Incorrectly places z (secondary aliphatic) above phenol, which is wrong. - (d) z > x > w > y: Incorrectly places aliphatic alcohols above phenol. Therefore, the correct answer is A.