Chapter 3& 5 HW Key
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CH341, Chapter 3&5 HW Answer Key
1. Give IUPAC names for the following structures.
a. /4-ethyl-6-methyldecane / c. /
2-bromo-4-tert-butyl-1-chlorocyclohexane
b. /
4,5-diisopropylnonane / d. /
1,1-dicyclobutyl-6,6-dicyclopropyheptane
2. Draw structures that correspond to the following names.
a. trans-1-ethyl-2-methylcyclopentane / b. (R)-3-chloro-5,5-dimethyloctane / c. 2-cyclohexyl-5-isobutylnonane3. Star (*) all of the asymmetric carbon atoms in the following structures.
a. / b.4.
a. Draw an enantiomer of the structure below.By drawing a mirror image of a chiral molecule (that does not have an internal mirror plane), you draw the enantiomer.
b. Draw a diastereomer of the structure below.
Original Diastereomer #1 Diastereomer #2
The original structure is on the left. Diastereomers are not mirror images. In the mirror image structure, the two asymmetric carbon atoms would both be in the “S” configuration. If we just change the configuration of only one of the asymmetric carbon atoms, it does not give us a mirror image of the original molecule, so we have made a diastereomer. Both of the structures given are diastereomers of the original molecule. What is the relationship of Diastereomer #1 to Diasteromer #2?
5. Rank each of the following sets of compounds from highest to lowest in boiling point. Explain your reasoning. If any compounds can hydrogen bond, show how they can.
a. /Alcohols have an O, which is more electronegative than the N of an amine. Therefore, alcohols will attract each other more strongly than amines or alkanes. Since N is more electronegative than C, amines will also attract each other by hydrogen bonding. Since C and H are similar in electronegativity, alkanes are not strongly attracted to one another, and have low boiling points.
b. /
Since an ether does not have a partially positive hydrogen, it only has London dispersion forces to attract other molecules of itself. Therefore, the biggest molecule has the highest boiling point.
6. Rank each of the following sets of compounds from highest to lowest in water-solubility. Explain your reasoning. If any compounds can hydrogen bond, show how they can.
a. /The ether on the left has two O’s that can hydrogen bond with water. The middle ether has one O, and the alkane on the right has none. The more hydrogen bonding with water, the more attraction for water, and the more water-soluble.
b. /
All of the ethers can hydrogen bond with water. Since the hydrocarbon part is not attracted to water, the most water-soluble is the one with the smallest hydrocarbon part.