Question

Which of the following can be classified as 'hexadecanoic acid' under IUPAC?

• A. Butyric acid
• B. Capric acid
• C. Palmitic acid
• D. Stearic acid

Hint:

Fatty Acid IUPAC Systematic Names:
Butyric (4:0) = Butanoic.
Caproic (6:0) = Hexanoic.
Caprylic (8:0) = Octanoic.
Capric (10:0) = Decanoic.
Lauric (12:0) = Dodecanoic.
Myristic (14:0) = Tetradecanoic.
PALMITIC (16:0) = HEXADECANOIC.
Stearic (18:0) = Octadecanoic.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
IUPAC chemical nomenclature of aliphatic saturated fatty acids: hexadecanoic acid contains an unbranched 16-carbon chain ($ ext{CH}_3( ext{CH}_2)_{14} ext{COOH}$, palmitic acid, 16:0).
Key Formula or Approach:
\[ \text{IUPAC: Hexadecanoic Acid} = \text{CH}_3\text{-(CH}_2)_{14}\text{-COOH} = \mathbf{Palmitic \text{ } Acid (16:0)} \]

Step 2: Detailed Explanation:
Systematic IUPAC vs common trivial names of saturated fatty acids:
1. Palmitic Acid (C): 16-carbon saturated fatty acid ($\text{C}_{16}\text{H}_{32}\text{O}_2$) $\rightarrow$ Hexadecanoic Acid under IUPAC.
2. Butyric Acid: 4-carbon saturated fatty acid $\rightarrow$ Butanoic Acid.
3. Capric Acid: 10-carbon saturated fatty acid $\rightarrow$ Decanoic Acid.
4. Stearic Acid: 18-carbon saturated fatty acid $\rightarrow$ Octadecanoic Acid.

Step 3: Final Answer:
Thus, Palmitic acid is classified as hexadecanoic acid under IUPAC, matching option (C).