1) Read the thermochemistry module in the StudyAids.[https://classes.yale.edu/chem220a/studyaids.html#Thermochemistry] 2) From the data presented on page 305, show with a diagram that the difference in the heat of combustion of 3-methyl-1-butene and 2-methyl-2-butene is 3.4 kcal/mole. Which alkene liberates more heat upon combustion? Given the DHfo for 2-methyl-2-butene [https://classes.yale.edu/chem220a/studyaids/thermo/heats-formation.html], what is the heat of formation of 3-methyl-1-butene? Calculate the heat of formation of 2-methylbutane. 3) In the homologous series (ethane ----> octane) what is the average incremental value of DHfo for a CH2 group? Show math. Using this value and the DHfo of 2-methylheptane in the module table (see problem 1), determine the heat of formation of 2-methylbutane. Show work. How does this value compare with the value obtained for 2-methylbutane in problem 2?

Aleksandr Mikhailovich Zaitsev [Saytzeff (German)] (1841-1910) University of Kazan

4) The E₂ elimination of cis-1-bromo-4-tert-butylcyclohexane with NaOC₂H₅ in ethanol occurs faster than the elimination of the trans isomer under the same conditions. Illustrate and explain.

5) Two optically active bromides (C₅H₁₁Br) A and B are independently heated in ethanol in the presence of NaOC₂H₅. Bromide A forms C (C₅H₁₀) and bromide B forms D (C₅H₁₀) leading to Zaitsev products. Both C and D are hydrogenated to form the same compound E (C₅H₁₂). The hydrogenation of C liberates 1.6 kcal/mole more heat than the hydrogenation of D. What are the structures of A-E? Explain and illustrate. [Tabular data appears in Chapter 6.]

6) What is the structure of the product in problem 4? Is it achiral, a racemate or a single enantiomer? The elimination in problem 4 can occur with hindered amines such as 1. What would you expect to happen when you use the (R,S)-amine in the elimination? The d,l-amine, i.e, the racemic amine? The (R,R)-amine or (S,S)-amine? [Think about Pasteur's method of resolution.]