Our base choice determines how much of the original acid is left in solution at equilibrium. This will have significant consequences during our discussion of the Aldol and Claisen reactions. For each of the reactions below determine which is the most acidic proton in the first molecule. Assign a pKa value to at least the most acidic proton. Draw the expected conjugate base and acid. Assign a pKa value to the conjugate acid then determine the approximate position of the equilibrium (towards the starting material, towards the product, or near the middle - for example there would be a significant amount of starting material and product at equilibrium). Then predict the product of the reaction of the conjugate base with the reagent over the next arrow. An example is provided below. Alcohol 16 Alcohol 16 HO st pKa = Most acidic HO 10 Phenol 38 Amine Albuterol pKa 10 stronger acid OH NaOCH HO HOCH₂ 16 pKa 16 weaker acid favored at equilibrium Difference in pKa values = 6 = 6 orders of magnitude difference therefore >99% of molecules look like product, very little neutal phenol and NaOCH, would be present in solution. OH HO 305x

Our base choice determines how much of the original acid is left in solution at equilibrium. This will have significant consequences during our discussion of the Aldol and Claisen reactions. For each of the reactions below determine which is the most acidic proton in the first molecule. Assign a pKa value to at least the most acidic proton. Draw the expected conjugate base and acid. Assign a pKa value to the conjugate acid then determine the approximate position of the equilibrium (towards the starting material, towards the product, or near the middle - for example there would be a significant amount of starting material and product at equilibrium). Then predict the product of the reaction of the conjugate base with the reagent over the next arrow. An example is provided below. Alcohol 16 Alcohol 16 HO st pKa = Most acidic HO 10 Phenol 38 Amine Albuterol pKa 10 stronger acid OH NaOCH HO HOCH₂ 16 pKa 16 weaker acid favored at equilibrium Difference in pKa values = 6 = 6 orders of magnitude difference therefore >99% of molecules look like product, very little neutal phenol and NaOCH, would be present in solution. OH HO 305x

Organic Chemistry: A Guided Inquiry

2nd Edition

ISBN:9780618974122

Author:Andrei Straumanis

Publisher:Andrei Straumanis

Chapter16: Synthesis Workshop 1

Section: Chapter Questions

Problem 14E

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