Which of the following is most soluble in water

Options

A. Normal butyl alcohol
B. Isobutyl alcohol
C. Tertiary butyl alcohol
D. Secondary butyl alcohol

Explanation

To determine which of the following alcohols is most soluble in water, we will analyze the structure and properties of each option provided: normal butyl alcohol, isobutyl alcohol, tertiary butyl alcohol, and secondary butyl alcohol.

### Step-by-Step Solution:

1. **Identify the Structures**:
- **Normal Butyl Alcohol (1-butanol)**: This is a straight-chain alcohol with the formula CH3-CH2-CH2-CH2-OH.
- **Isobutyl Alcohol (2-methyl-1-propanol)**: This has a branched structure with the formula (CH3)2CH-CH2-OH.
- **Tertiary Butyl Alcohol (2-methyl-2-propanol)**: This is a highly branched alcohol with the formula (CH3)3C-OH.
- **Secondary Butyl Alcohol (2-butanol)**: This has a structure where the hydroxyl group is attached to the second carbon in a straight chain, with the formula CH3-CH(OH)-CH2-CH3.

2. **Understand Hydrogen Bonding**:
- All alcohols can form hydrogen bonds with water due to the presence of the hydroxyl (-OH) group. This is a key factor in their solubility.

3. **Consider Hydrophobic vs. Hydrophilic Character**:
- The longer the carbon chain (hydrophobic part), the less soluble the alcohol tends to be in water. The hydrophobic nature of the carbon chains can hinder solubility.
- Tertiary butyl alcohol has a bulky structure with three methyl groups attached to the central carbon, which reduces the surface area in contact with water.

4. **Evaluate Solubility**:
- **Normal Butyl Alcohol**: Has a longer carbon chain, which makes it less soluble.
- **Isobutyl Alcohol**: Also has a branched structure but is still less soluble than tertiary butyl alcohol.
- **Tertiary Butyl Alcohol**: Due to its bulky structure and lower surface area, it experiences less repulsion from water molecules, leading to higher solubility.
- **Secondary Butyl Alcohol**: Has moderate solubility, but still less than tertiary butyl alcohol.

5. **Conclusion**:
- Among the four alcohols, tertiary butyl alcohol is the most soluble in water due to its unique structure, which minimizes the hydrophobic interactions.

### Final Answer:
**Tertiary Butyl Alcohol (Option 3) is the most soluble in water.**

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