See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of C–H Bond Strength for Homolytic Fission **Key Principle:** Weaker C–H bonds require less energy for homolytic fission (breaking into radicals: R–H → R• + H•). **Bond Strength Factors:** - C–H bonds are weaker when the resulting carbon radical is more stabilized - Radical stability order: **tertiary > secondary > primary > methyl** **Evaluation of Each Option:** **(A) Benzene C–H:** - Forms a primary phenyl radical (aryl radicals are very unstable) - High bond dissociation energy (~110 kcal/mol) **(B) Benzyl C–H (benzylic):** - Forms a benzylic radical: $C_6H_5CH_2•$ - Stabilized by resonance with aromatic ring - Moderate bond dissociation energy (~85 kcal/mol) **(C) Methane C–H:** - Forms methyl radical (minimal stabilization) - Bond dissociation energy (~104 kcal/mol) **(D) Triphenylmethane C–H:** - Forms triphenylmethyl radical: $(C_6H_5)_3C•$ - **Highly stabilized** by resonance with **three aromatic rings** - Exceptional resonance stabilization → **lowest bond energy (~77 kcal/mol)** **Answer: (D)** because the tertiary carbon bearing three phenyl groups produces a triphenylmethyl radical with maximum resonance stabilization, making this C–H bond the weakest.