The degrees of unsaturation for C10H13BrO2 is which value?

The degrees of unsaturation for C10H13BrO2 is which value?

• A. 4
• B. 5
• C. 6
• D. 7

Answer: (B)

Degrees of unsaturation count how many rings plus pi bonds a molecule has. The oxygen atoms don’t affect this count, while halogens count like hydrogens in the formula. Use DBE = (2C + 2 + N − H − X)/2. For C10H13BrO2: C = 10, H = 13, N = 0, X (halogens) = 1 (Br). Plugging in gives DBE = (2×10 + 2 − 13 − 1)/2 = (20 + 2 − 13 − 1)/2 = 8/2 = 4. So there are four degrees of unsaturation. A benzene ring alone accounts for four (one ring and three C=C bonds), so the rest of the molecule’s substituents (the Br and two oxygens) must be arranged without adding extra rings or pi bonds.

Degrees of unsaturation count how many rings plus pi bonds a molecule has. The oxygen atoms don’t affect this count, while halogens count like hydrogens in the formula. Use DBE = (2C + 2 + N − H − X)/2.

For C10H13BrO2: C = 10, H = 13, N = 0, X (halogens) = 1 (Br). Plugging in gives DBE = (2×10 + 2 − 13 − 1)/2 = (20 + 2 − 13 − 1)/2 = 8/2 = 4.

So there are four degrees of unsaturation. A benzene ring alone accounts for four (one ring and three C=C bonds), so the rest of the molecule’s substituents (the Br and two oxygens) must be arranged without adding extra rings or pi bonds.