Fall, 2013 Chemistry 2311 Homework Problems- Chapter 7 (1) Name each of the following compounds. Designate E,Z, cis-, trans-, and R,S configurations. (a) (b) (c) (d)(e) (2) Place the following alkenes in the order of decreasing stability. (3) Predict the structure for the major products for each of the following reactions. (a) (b)(c) (d) (e) (f) (g)(h) (i) (j) (k)(l) (m) (4) Write a detailed mechanism for the following reaction.(5) Provide a brief mechanistic explanation for each of the following. (a) Dehydrohalogenation of (1S,2R)-1-bromo-1,2-diphenylpropane produces only (E)-1,2-diphenylpropene. (b) 1-Bromobicyclo[2.2.1]heptanes does not undergo elimination when heated with sodium ethoxide in ethanol.(6) Indicate True (T) or False (F) for each of the following statements. (a) trans-2-heptene is thermodynamically less stable than 1-heptene. (b) trans-2-butene is thermodynamically more stable than cis-2-butene but cis-cyclooctene is more stable than trans-cyclooctene. (c) Whenever an elimination reaction occurs to give the less stable, less highly substituted alkene, the elimination process is said to follow the Hofmann rule. (d) When an elimination reaction occurs to give the most stable, most highly substituted alkene, the elimination process is said to follow the Zaitsev rule. (e) The preferential formation of one product, because the free energy of activation leading to its formation is lower than that for another product, is termed thermodynamic control. (f) Bulky organic bases such as potassium tert-butoxide in tert-butyl alcohol are employed in elimination reaction of 2-bromo-2-methyl butane in order to form the less stable alkene product. (g) The tert-butyl carbocation is a Lewis base. (h) Alcohols can be Lewis bases. (i) A secondary carbocation is less stable than a tertiary carbocation. (j) A geminal dihalide has halogen atoms on adjacent carbon atoms. (k) Aceylene is more acidic than ethylene. (l) The heterogeneous addition of hydrogen (H2 + Pt) to 2-butyne results in the preferential formation of trans-2-butene. (m) The addition of hydrogen to 1-butene in the presence of a Pt catalyst is highly endothermic. (n) The lowest energy geometry for the E2 transition state is the anti-coplanar arrangement of the beta C-H bond and C-X bond. (o) In general, eliminations reactions are favored over competing substitution reactions at lower temperatures. (p) A carbanion is an intermediate in the E1 process. (q) Acetylene is a stronger acid than ethanol.(r) When trans-2-methylcyclohexanol is subjected to acid-catalyzed dehydration, the major product is 1-methylcyclohexene. (s) When trans-1-bromo-2-methylcyclohexane is reacted with sodium ethoxide in ethanol, the major product is 3-methylcyclohexene. (7) How would you carry out the following synthetic transformations? You may use any needed reagents. The transformations will require several steps.
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