ps5 - Massachusetts Institute of Technology Problem Set 5,...

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Unformatted text preview: Massachusetts Institute of Technology Problem Set 5, Due 4pm March 31 5.12, Spring 2005 1. Draw the products of the following reactions. Ignore stereochemistry. a. H H b. H H H2SO4, HgSO4, H2O 1. NaNH2, NH3 2. O 1. NaNH2, NH3 2. O 3. H2O 2. a. Draw the molecular orbital diagram of ethyne. b. What is the pKa of ethyne? c. What is the pKa of ethane? d. n-butyl lithium is a commercially available form of an alklyl anion. Draw the structure of the product of the following reaction. H Li+ 1 3. Design a multistep synthesis for the following compound 2-methyl-tridec-5ene. Organic starting materials are provided. You need to provide reagents. starting materials H Product: 2-methyl-tridec-5-ene H Br Br 2 4. Starting from acetylene (also known as ethyne) and a ketone, design a synthesis of the following compound (ignore stereochemistry). HO 3 5. Suggest a multi-step synthesis of 2-bromobutane from acetylene (ethyne). 4 6. a. Fill in the missing intermediates. O Mg, Et2O Br b. Design a multistep synthesis for 3-deutero-2,2,4,4-tetramethylpentane from 2,2,4,4-tetramethylpentane. D 3-deutero-2,2,4,4-tetramethylpentane 2,2,4,4-tetramethylpentane 5 7. Br2, hu a. Write the structures of the products of the above reaction. b. Use the following bond dissociation energies to calculate the DH˚ for the formation of the major and minor products. 100 kcal/mol H 105 kcal/mol H 46 kcal/mol Br Br 70 kcal/mol Br Br H Br 74 kcal/mol 87.5 kcal/mol c. The relative rate of abstraction of a tertiary hydrogen is 1600; secondary is 82 and primary is 1. Calculate the percent yield for each product of the reaction. d. Draw a mechanism for the formation of the major product. 6 8. Draw the major products of the following reactions. NBS, heat NBS, heat 9. Write the structures expected from the monochlorination of 2-methylbutane via a radical reaction. Using the relative reactivities of 1:4:5 for replacement of primary, secondary and tertiary hydrogens, determine the percentage of each of the monochloro compounds expected in the product mixture. 8 ...
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