ANSWERS TO EXAM 1 - CHEM 227 - HARDING - SPRING 1997

Norethindrone is a progesterone component of some types of birth control pills. Use this structure to answer the following questions.

1. (6 pts) Circle and name three functional groups in the above molecule.

2. (6 pts) Predict the hybridization of each of the atoms marked with an arrow in the structure below.

3. (4 pts) Predict the indicated bond angles for norethindrone.

4. (2 pts) Describe the circled bond in the norethindrone structure below in terms of the atomic orbitals involved.

Sigma bond involving overlap of C_sp-C_sp3 atomic orbitals

5. (8 pts) Label each atom indicated as 1, 2, 3, or 4.

6. (8 pts) Alkyl nitrile oxides (RCNO) are a useful class of compounds for synthesis of complex molecules. One of the less significant resonance forms of methyl nitrile oxide is shown below. Write the structures for two additional resonance forms (both with filled valence shells for all atoms and formal charges between -1 and +1). Be sure to include writing the formal charge as needed.

7. (12 pts) Write the products expected for the acid-base reactions below. Draw in all non-bonding electrons in the products and draw arrows showing the electron flow in the reactions.
a)

This is exactly same as Problem 2.18

b)

8. (4 pts) Label the acid and base in each reactant pair above.

(See above)

9. (8 pts) Draw correct structures corresponding to the following names.

1. 2,5-dimethyl-3-(1-methylethyl)hexane b) cis-1-methyl-3-(1-methylcylobutyl)cyclopentane

10. (8 pts) Draw a Newman projections showing the six possible conformations for the structure below using the C₁-C₂ bond for analysis.

Draw the conformations sequentially with the indicated bond rotations. Rotate only the front carbon. Circle the highest energy staggered conformation.

11. (6 pts) Draw in all equatorial C-H bonds on the cyclohexane chair shown below.

12. (8 pts)

a) Complete the drawings below to show the two chair conformations for trans-1,3-dimethylcyclohexane.

b) Which structure is more stable? Equal energy; each has one axial methyl group

13. (4 pts) Convert the Newman projection below to a wedge-dash representation.

14. (4 pts) Indicate whether the equilibrium below favors the reactants or products.

The equilibrium favors the _____reactants__________.

weak acid stronger acid

15. (6 pts) Draw a three-dimensional representation for CF₂Cl₂ (Freon® 12) using solid, wedge, and dashed lines. Draw an arrow showing clearly the expected dipole moment for this compound.

16. (6 pts) Draw three (3) different branched chain isomers for the alkane C₇H₁₆. Each compound shown must have a different length parent chain.