From the following, how many compounds contain at least one secondary alcohol?
Choose the correct answer from the options given below :

Solution

Chemistry ma’am · 2 steps

Go to every OH, look at the carbon holding it, and count how many carbons that carbon is bonded to.

1. Classify each OH. An OH carbon bonded to one other carbon is primary (-CH₂OH). One bonded to two carbons is secondary (>CH-OH). One bonded to three carbons is tertiary. An OH on a C=O is part of an acid group, so it is not an alcohol at all.

   Compound	Carbons holding an OH	Secondary alcohol?
   (I)	two -CH₂OH (1°). The -COOH on N is an acid, not an alcohol	No
   (II)	-CH₂OH (1°) and CH bonded to the ethyl carbon and the CH₂OH carbon (2°)	Yes
   (III)	ring C bonded to 2 ring carbons and the side chain (3°), and C(CH₃)₂OH (3°)	No
   (IV)	ring CH next to CH₂ (2°), ring C carrying CH₃ (3°), side-chain CH (2°), CH₂OH (1°)	Yes
   (V)	C carrying ethyl and CH₃ (3°), and CH(OH)CH₃ (2°)	Yes
   (VI)	CH₂OH (1°), C carrying CH₃ (3°), C(CH₃)₂OH (3°)	No

2. So. Only (II), (IV) and (V) have a secondary alcohol. That is three compounds, option (a).

The idea to keep. The degree of an alcohol is the degree of the carbon holding the OH. Count carbon neighbours only, not the H, O or N atoms, and remember a ring carbon counts its ring neighbours too.

Answer from the NTA final answer key. Solution by PrepWiser.