Q.26 Which of the following compounds have the same degree of reduction per
carbon-mole?
(A) Glucose
(B) Lactic acid
(C) Acetic acid
(D) Formic acid
Glucose vs Lactic Acid vs Acetic Acid vs Formic Acid
These three compounds have identical degree of reduction per carbon-mole = 4. Formic acid has γ = 2 per carbon.
Understanding Degree of Reduction Per Carbon-Mole
Degree of reduction per carbon-mole measures the average available electrons for oxidation per carbon atom in organic compounds. This key biochemical parameter is calculated as total degree of reduction (γ) divided by the number of carbon atoms.
The standard formula is: γ = 4c + h - 2o where c, h, and o represent atoms of carbon, hydrogen, and oxygen respectively.
γ = 4 × (number of C atoms) + 1 × (number of H atoms) - 2 × (number of O atoms)Per carbon-mole: γper C = γ ÷ (number of C atoms)
Detailed Calculations for Each Compound
Glucose (C₆H₁₂O₆) – Option A
Per carbon: 24 ÷ 6 = 4
Lactic Acid (C₃H₆O₃) – Option B
Per carbon: 12 ÷ 3 = 4
Acetic Acid (C₂H₄O₂) – Option C
Per carbon: 8 ÷ 2 = 4
Formic Acid (HCOOH or CH₂O₂) – Option D
Per carbon: 2 ÷ 1 = 2
⚠️ Important Correction
While glucose, lactic acid, and acetic acid all have degree of reduction = 4 per carbon-mole, formic acid has γ = 2 per carbon-mole. This makes A, B, and C the compounds with identical reduction degrees.
Biochemical Significance
Compounds with γ = 4 per carbon represent the standard reduction level of carbohydrates and related metabolites. This uniformity explains why glucose, lactic acid, and acetic acid maintain balanced electron availability during metabolic pathways like glycolysis and fermentation.
Formic acid’s lower reduction state (γ = 2) reflects its higher oxidation level, positioning it closer to fully oxidized CO₂ (γ = 0).
Quick Reference Table
| Compound | Formula | Total γ | γ per C |
|---|---|---|---|
| Glucose | C₆H₁₂O₆ | 24 | 4 |
| Lactic Acid | C₃H₆O₃ | 12 | 4 |
| Acetic Acid | C₂H₄O₂ | 8 | 4 |
| Formic Acid | CH₂O₂ | 2 | 2 |
