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9.39 The reactant in this problem is the same as in Problem 9.38a. However, the reaction conditions are different. In Problem 9.38a, the reaction was conducted with the strong base, ethoxide anion, so the mechanism was E2 and anti elimination was preferred. In this problem, there is no strong base present, so the mechanism is First the CI leaves to form a carbocation. Because the carbocation is planar, stereochemistry is lost and anti elimination is not required. So both products are formed. Product 2 should be the major elimination product because E1 reactions follow Zaitsev's rule. Review of Mastery Goals After completing this chapter, you should be able to: Provide a detailed description, including stereochemistry, for the E2 mechanism and summarize the conditions that favor its occurrence. (Problems 9.2, 9.3, 9.4, 9.5, 9.6, 9.20, 9.21, 9.23, and 9.24) Provide similar information about the E1 mechanism. (Problems 9.11, 9.12, 9.19, 9.28, and 9.33) Understand Zaitsev's rule and Hofmann's rule and when each applies. (Problems 9.7, 9.8, 9.9, and 9.17) Show the expected products, including stereochemistry and regiochemistry, of any elimination reaction. (Problems 9.1, 9.5, 9.10, 9.13, 9.14, 9.17, 9.22, 9.27, 9.34, 9.36, and 9.37) Predict whether the major pathway that will be followed under a particular set of reaction conditions will be SN1, SN2, E1, or E2. (Problems 9.15, 9.16, 9.18, 9.25, and 9.26) 146