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Suggested solutions for Chapter 9 Problem 1 Propose mechanisms for the first four reactions in the chapter. 0 oH 0 H 1. Li 1. H 2. H2O 2. 0 H 0 1. 1. MgBr Ho H 2. H+, H2O 2. H2O Purpose of the problem Rehearsal of the basic reactions of Chapter 9. Suggested solution Each reaction simply involves the nucleophilic attack of the organometallic reagent on the aldehyde ketone followed by protonation. You may draw the intermediate as an anion or with an O--metal as you please. Note the atom-specific arrows to show which atom is nucleophilic. In the second example the allyl-lithium might attack through its other end. 0 Li 0 H 0 Li H 0 H H product product 0 H 0 H 0 product product MgBr H Problem 2 When this reaction is carried out with allyl bromide labelled as shown with ¹³C, the label is found equally distributed between the ends of the allyl system in the product. Explain how this is possible. How would you detect the distribution in the product? OH Br 1. Mg, THF Ph 2. PhCHO ¹³C Purpose of the problem Reminder of the way allyl-metals react and revision of NMR.