Chapter 15.13, Problem 15.33E

SN2 Reaction lodide ion is an effective nucleophile in S2 displacements. In acetone solution, other alkyl halides can be converted to alkyl iodides: CH;CH2 CH,CH3 I-C H;C H acetone X- Na I- H CH3 Na X X-Clor Br TR) Although you might expect such a reaction to be reversible, it can be made to proceed in the forward direction by using anhydrous acetone as the solvent because sodium iodide is soluble in this solvent, but sodium chloride and sodium bromide are not. We can detect whether a reaction has occurred by the formation of a precipitate of sodium chloride or bromide.

Explain, by using words and structures, why when aniline is added to acetic anhydride and AlCl3 there is no product formed from a Friedel-Crafts reaction.

5. Optically pure 2-octyl sulfonate was treated with varying mixtures of water and dioxane, and the optical purity of the resulting product (2-octanol) was found to vary with the ratio of water to dioxane, as shown in the following table (J. Am. Chem. Soc. 1965, 87, 287-291). Given that dioxane possesses fairly nucleophilic oxygen atoms, provide a complete mechanism that explains the variation in in the product's optical purity due to changes in solvent composition. Hint, the solvent is doing more here than just dissolving.. it is partaking in the reaction. Solvent Ratio (water : dioxane) 25:75 50: 50 75: 25 100 :0 Optical purity of (S)-2-octanol 77% 88% 95% 100% H20 он (R)-2-Octyl sulfonate (optically pure) (S)-2-Octanol (dioxane)

Carboxylic acids are lowest in reactivity towards nucleophilic substitution. Why? (Consider the reaction between acetic acid and sodium methoxide).

We used biphenyl instead of benzene for Friedel-Crafts alkylation. What would you predict the major product would be if we had used benzene instead?  Why?

During Friedel Crafts Acylation , Why does AlCl3 have to be anhydrous??

Brevicomin, the aggregation pheromone of the western pine bark beetle, contains a bicyclic bridged ring system and is prepared by the acid-catalyzed cyclization of 6,7-dihydroxynonan- 2-one. a. Suggest a structure for brevicomin. b. Devise a synthesis of 6,7-dihydroxynonan-2-one from 6-bromohexan-2-one. You may also use three-carbon alcohols and any required organic or inorganic reagents.

a. sec-butyl alcohol remains optically active in aqueous base, but racemizes when mixed with dilute sulfuric acid. Suggest a mechanism accounting for this observation. b. The following 1935 experiment established that in SN2 reactions, a molecule undergoes an inversion of configuration. Optically active 2-iodooctane was reacted to with Na1311 in acetone. It was observed that the rate of reaction depended on both [RI] and [I-], but the rate of racemization was two times faster than isotopic exchange. Explain this set of results. c. Explain the following observations: (i) why neomenthyl chloride and menthyl chloride yields the following products below; and, (ii) why menthyl chloride reacts 1/200 times as fast as neomenthyl chloride to yield the same product as neomenthyl chloride. da C neomenthyl chloride 2-menthene 25% 2-menthene 75% menthyl chloride 2-menthene only product

Friedel–Crafts acylation of the individual isomers of xylene with acetyl chloride and aluminum chloride yields a single product, different for each xylene isomer, in high yield in each case. Write the structures of the products of acetylation of o-, m-, and p-xylene.