Chem 220a

Problem Set 2

Chapters 3

Due: Monday, September 25, 2000

Odd Hassel (Norway) 1897-1981

Derek H. Barton (U.K.) 1918-1998

1969 Nobel Prize in Chemistry - Development of the Concept of Conformation

1) You are responsible for the Conformation Module in the Study Aids. 

2) Name (IUPAC) the following alkane and redraw it using a line-angle having the longest chain horizontal. For a dynamic (Chime) view, click here. For a static view click here.

3) "SUVs are BAD for the environment, your wallet and other drivers." by Abram Katz, New Haven Register, Sept. 14, 2000. "...But the Sierra Club has assembled some fascinating facts and figures.....A Cherorover-type behemoth averages 13 to 15 miles per gallon. Over a 124,000-mile lifetime, one SUV will generate an astonishing 134 tons of carbon dioxide. This is because one gallon of gasoline burned releases 28 pounds of carbon dioxide." Assume that gasoline is octane. a) Recalculate the 28 pound figure. b) Using your value from a) and the lowest value for the mileage, calculate the tons of CO2 generated over the lifetime of the vehicle. How do your values compare with those of the Sierra Club?

4) n-Octane has b.p. = 126 oC and m.p. = -57 oC. Yet one of the isomeric octanes has b.p. = 106 oC and m.p. = 100 oC. In the later case there is only a six degree difference between the melting point and the boiling point. What is the structure of the isomeric octane? Explain.

5) There is a cis and a trans 1,3-dimethylcyclohexane. Draw each one in both of its chair conformations. Which one has a value of DGo = 0 kcal/mol for the difference in energy between its two chair conformations? What can you say (not calculate) about DGo for the two chair conformations of the other 1,3-dimethylcyclohexane?

6) The heat of combustion of n-octane is 1303 kcal/mol. Estimate the heat of combustion of n-decane. Show work.

7) Compound A and B are both 1,4-disubstituted cyclohexane stereoisomers. The difference in energy between the chair conformations of A is 1.1 kcal/mol and the difference in energy between the chair conformations of B is 2.3 kcal/mol. What are the structures of A and B? Show work. Use the table on pg. 118 in your text.

8) Do problem 6, PS2, 1999.

 

 

 

 

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