Final Exam
Tuesday, December 16, 1997

1) For the following pairs of compounds, check whether they are identical, constitutional isomers, enantiomers, or diastereomers. (15 points)

2) Draw the structure of meso-1,3-dichloro-1,3-dimethylcyclopentane. (5 points)

3) a) For each of the following 1-bromo-3-tert-butylcyclohexane diastereomers, draw the most stable chair conformation. (16 points)

b) Indicate which of the above isomers will undergo E2 elimination the fastest, and briefly explain your answer. (10 points)

The cis isomer the trans isomer

explain:

4) Determine whether the following molecules have the R or S configuration. (10 points)

5) 3-Methyl-2-cyclopenten-1-ol will undergo a substitution reaction when treated with HCl to give the more substituted 3° chloride as the major product.

a) Explain the origin of the product by drawing the structure of the intermediate involved in this reaction. (15 points)

b) Is this an example of an SN1 or an SN2 reaction? (4 points)

SN1

c) Sketch the reaction diagram for this reaction, and indicate on the diagram where the intermediate lies and which step is rate determining. (10 points)

6) A molecule with the formula C6H12O2 shows a characteristic Infrared absorption at 1735 cm-1 and the following NMR spectra. The proton spectra shows the peaks, the number of hydrogens that each resonance integrates for, and the coupling constant (J in Hz). The carbon spectrum shows 5 different carbons.

a) Calculate the degrees of unsaturation in this molecule: (5 points)

1

b) What functional group does the IR absorption at 1735 cm-1 correspond to? (5 points)

Carbonyl C=O (ester)

c) Draw the structure of this molecule (partial credit will be given for correct "pieces" of the molecule if they match the NMR data). (15 points)

7) You are given a sample which contains one of the following constitutional isomers. The infrared spectrum shows C-H stretches at 3035 and 2910 cm-1. There are no other strong absorptions. The mass spectrum shows the mass for the sample of m/z = 100. In addition, a large abundance of an ion at m/z = 71 also appears. Given this data, which of the following structures is the correct one (circle your answer). (8 points)

atomic mass: C - 12, H - 1, O - 16

8) For the following compounds, determine the number of sigma bonds, and indicate the hybridization of the specified atoms. (8 points)

9) For the following free radical chain reaction steps, indicate whether it is an initiation, propogation, or termination step. (8 points)

10) Draw the major organic product for the following reactions. Be sure to indicate stereochemistry where appropriate. (21 points)

11) Provide the missing reagents for the following reactions. (15 points)

12) For the following pairs of molecules, indicate whether or not they are equal in energy. If not, circle the structure that is lowest in energy. (6 points)

13) Starting from 1-butene and any other reagents you need, show how you would synthesize 3,3,4,4-tetrabromohexane. Show all structures and reagents for each step. (20 points)