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50 Chapter 3 REACTIONS OF ALKANES So, Yield of 1-chloro-3-methylpentane = 100% X 6/(6 + 16 + 5 + 3) = 100% X 6/30 = 20% Yield of = 100% X 16/30 = 53% Yield of 3-chloro-3-methylpentane = 100% X 5/30 = 17% Yield of 3-(chloromethyl)pentane = 100% X 3/30 = 10% (c) Propagation step 1 [values below are DH° (kcal for bonds made or broken]: CH₃ CH₃ + HCI + 96.5 103 = 96.5 - 103 = -6.5 Propagation step 2: CH₃ CH₃ + Cl₂ + 58 85 = -27 For the reaction overall, = 33.5 kcal mol⁻¹. 22. The mechanism is qualitatively the same as that of chlorination of methane (textbook Section 3-4): Initiation: Br₂ 2 Br. Propagation: (1) Br. + CH₄ CH₃· + HBr (2) CH₃· + Br₂ CH₃Br + Br. Termination: Br. + Br. Br₂ CH₃· + Br. CH₃Br CH₃· + CH₃CH₃ 23. The data needed to prepare these diagrams may be found in Table 3-5. Examples to use as models include Figures 3-7 and 3-8. First propagation step Second propagation step + Br₂ + HBr: E E = = + 18 kcal 24 kcal mol⁻¹ CH, + + :Br. Reaction coordinate Reaction coordinate