Homework answers / question archive / University of Pittsburgh-Pittsburgh Campus CHEM 0310 1)Determine R/S for the following chiral centers                                                                     Label the degree of oxidation of the indicated carbons in the following compound

University of Pittsburgh-Pittsburgh Campus CHEM 0310 1)Determine R/S for the following chiral centers                                                                     Label the degree of oxidation of the indicated carbons in the following compound

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University of Pittsburgh-Pittsburgh Campus

CHEM 0310

1)Determine R/S for the following chiral centers

 

 

                                                           

 

 

2. Label the degree of oxidation of the indicated carbons in the following compound. 

                    

 

 

 

 

3. Explain why stability order of carbon radicals, carbocations and alkenes follow the similar trend.                   

 

 

 

4. Write True  (T) or False (F) against each statement

 

1. 1. Epoxide opening is a stereoselective reaction:    
   2. Williamson’s ether synthesis involves carbocation formation:  
   3. Bromination with H-Br may lead to rearrangement:  
   4. E2 reaction involves multiple steps:  
   5. Main driving force for rearrangement reaction is to generate stable carbocation:
   6. Methanol is a stronger acid than tertiary butanol:
   7. Oxacyclopropane is more reactive than ethanol:
   8. In ¹H NMR # of peaks corresponds to # of different kinds of Hs:
   1. Deuterium is NMR active:
   10. Meso compounds do not have chiral centers:
   11. Energy of transition state is proportional to the rate of a reaction:  L. Bromination of butane in presence of light is stereospecific:

 

5. Draw the structures of the products in the following reactions. Mention the stereochemical outcomes of these reactions.

 

 

-          -

 

6. Write the reagents for the following sequential transformations. 

 

 

7. Draw the structures of the products in the following reactions.

 

 

 

 

 

8. Draw the product of the following reaction. Indicate the name of the reaction. Show arrow-pushing mechanism. Draw the potential energy diagram and structure of the transition state. 

 

 

9. Draw all chair forms of the following molecule and indicate which one is the most stable. Explain your choice in a few words.

 

 

 

10. Provide examples of each of the following:

 

 

 

 

 

11. Are the following pairs of structures enantiomers, diastereomers, constitutional isomers, or the same?

 

 

 

12. Circle the word or phrase within each set of brackets that best completes the sentence.  

 

1. In an S_N2 reaction, doubling the concentration of nucleophile will   the rate of product formation.

 

2. halogenation of alkane in presence light involves formation of
3. Bromination of alkene involves formation of

 

4. Consider the figure below, which depicts an ethyl radical: 

 

H

H

 

H

H

                                      ^H

 

The interaction indicated by the dotted line is an example of 

and the interaction is energetically

 

5. In the following compound one functional group is
6. For a pair of molecules with the same connectivity that are not superimposable and not mirror images, the relationship is best described as  

13. Write clear, step-by-step mechanisms for the following reactions. Use arrows to track electron flow. Be sure your mechanism accounts for the indicated stereochemical outcome.

 

 

 

 

14. Multiple-choice question: Circle the right answer

 

A chiral center

1. Is sp2 hybridized
2. Is sp3 hybridized
3. Is quaternary carbon
4. Has vacant p orbital

 

 

15. Match entries in column A with column B

 

1. 1. Alcohol Electrophile
   2. E2 reaction    chiral compound
   3. Optical activity           hydroxyl functional group
   4. Carbocation  bimolecular 

 

16. Draw the structure of major product for each of the reactions below. You may ignore stereochemistry. 

 

 

 

                              

17. Draw the major organic product that will form in the following reactions. Pay attention to stereochemistry. If no reaction will take place, mark “no reaction.” 

 

 

 

 

18. Reactions of 2-bromo-3-methylbutane with sodium methoxide and sodium isopropoxide furnish different major products. Write these reactions and explain the product formations.    

 

 

 

19. Indicate the number of different signals that will be observed in the ¹H-NMR spectrum of the molecule below. Ignore spin-spin splitting. 

 

 

3

3

 

20. Write the splitting pattern of the indicated protons in the following compounds. 

 

 

O

Br

Br

 

 

O

 

 

 

 

21. The structure and ¹H-NMR spectrum of an organic molecule are shown below. Fill in each box next to the molecule with the letter that corresponds to the ¹H-NMR signal of the hydrogen(s) attached to the indicated carbon.