Among the following compound which can be dehydrated very easily is

The ease of dehydration depends directly on the stability of the resulting carbocation:

$$\text{Tertiary } (3^{\circ}) > \text{Secondary } (2^{\circ}) > \text{Primary } (1^{\circ})$$

For carbocations of the same degree, stability is further governed by the number of $$\alpha$$-hydrogens available to stabilize the positive charge via hyperconjugation and inductive effects.

Structure and Intermediate Analysis:

• Option A: Pentan-1-ol

  $$\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{OH} \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\overset{+}{\text{C}}\text{H}_2$$

  Forms a primary ($$1^{\circ}$$) carbocation ($$2$$ $$\alpha$$-hydrogens). This is highly unstable and very difficult to dehydrate.

• Option B: 2-Pentanol

  $$\text{CH}_3\text{CH}_2\text{CH}_2\text{CH(OH)CH}_3 \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2\overset{+}{\text{C}}\text{HCH}_3$$

  Forms a secondary ($$2^{\circ}$$) carbocation with $$5$$ $$\alpha$$-hydrogens ($$2$$ from the adjacent $$-\text{CH}_2-$$ group and $$3$$ from the terminal $$-\text{CH}_3$$ group).

• Option C: 2-Butanol

  $$\text{CH}_3\text{CH}_2\text{CH(OH)CH}_3 \rightarrow \text{CH}_3\text{CH}_2\overset{+}{\text{C}}\text{HCH}_3$$

  Forms a secondary ($$2^{\circ}$$) carbocation with $$5$$ $$\alpha$$-hydrogens ($$2$$ from the adjacent $$-\text{CH}_2-$$ group and $$3$$ from the terminal $$-\text{CH}_3$$ group).

• Option D: 2-Heptanol

  $$\text{CH}_3(\text{CH}_2)_4\text{CH(OH)CH}_3 \rightarrow \text{CH}_3(\text{CH}_2)_3\text{CH}_2\overset{+}{\text{C}}\text{HCH}_3$$

  Forms a secondary ($$2^{\circ}$$) carbocation with $$5$$ $$\alpha$$-hydrogens ($$2$$ from the adjacent $$-\text{CH}_2-$$ group and $$3$$ from the terminal $$-\text{CH}_3$$ group).

Evaluating the Secondary ($$2^{\circ}$$) Alcohols:

While 2-pentanol, 2-butanol, and 2-heptanol all form secondary carbocations with $$5$$ $$\alpha$$-hydrogens, 2-butanol has the smallest alkyl chain backbone.

As the size of the hydrophobic alkyl group increases (from butyl to pentyl to heptyl), steric hindrance in the transition state slightly increases, and the overall volatility/reactivity trends favor the smaller molecular weight system under standard experimental conditions. Therefore, 2-butanol yields its carbocation framework with the lowest relative activation barrier.

Answer: Option C — 2-butanol