1. Draw a standard line bond structure for compounds of the following molecular formulas:

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1 TF ame: LS1a Fall 06 Problem Set #1 Due Friday 9/29 at noon in your TF s drop box on the 2 nd floor of Science Center all questions including extra ones should be turned in 1. Draw a standard line bond structure for compounds of the following molecular formulas: (a) CH 3 CH 2 CH 2 H (b) H 2 CH 2 CH (c) (C 6 H 5 )C 2. Provide a molecular formula for each of the following molecules. Describe the geometry at the circled carbon atoms. (a) caffeine (b) THG ( The Clear ) (c) DEET H H 3. Shown below are four structures. For each possible pair of structures (a-b, a-c, a-d, b-c, b-d, and c-d), indicate whether the two structures represent the same molecule (including different conformations of the same molecule), or whether they represent enantiomers. (a) H H H (b) H H H (c) H H H (d) H H H

2 TF ame: 4. H H H H H H H H (a) Draw one possible wedge and dash structure of the molecule above, showing the hydrogens at chiral centers. (b) What is the total number of potential stereoisomers for this molecule? Draw one additional stereoisomer. (c) aringin, one of the stereoisomers of this molecule, gives grapefruit its bitter taste. However, other stereoisomers of this molecule do not taste biter at all. Why might this be?

3 TF ame: 5. (a) Can two molecules of ethanol (CH 3 CH 2 H) form hydrogen bonds with each other? If so, draw a hydrogen bonding interaction between two molecules of ethanol and label the donor and acceptor. If not, explain why not. (b) Draw all of the hydrogen bonds you would expect a molecule of ethanol to form when a small amount of ethanol is added to a large amount of water. (c) Can two molecules of ethyl ether (CH 3 CH 2 CH 2 CH 3 ) form hydrogen bonds with each other? If so, draw a hydrogen bonding interaction between two molecules of ethyl ether and label the donor and acceptor. If not, explain why not. (b) Draw all of the hydrogen bonds you would expect a molecule of ethyl ether to form when a small amount of ethyl ether is added to a large amount of water.

4 TF ame: 6. Shown below is part of a protein interacting with part of a DA strand. protein H H H 2 H 2 P DA DA (a) Draw all lone pairs on all the nitrogen and oxygen atoms, assuming that all nitrogen and oxygen atoms fulfill the octet rule. (b) Calculate the formal charge on all the nitrogen and oxygen atoms. (c) What types interactions between the protein and DA would you expect to be present in the region shown above? 7. Fats and oils are composed of compounds called triacylglycerides. The general structure of a triacylglyceride is shown below. R 1, R 2 and R 3 are different fatty acids (ote: Chemists use "R" groups to represent a portion of the molecule that is not drawn out. R groups with different subscripted numbers are used to differentiate between the different "R" groups in a molecule.) H 2 C R 3 (a) If R 1, R 2 and R 3 are all different, is the triacylglyceride chiral? If so, circle the chiral center(s).

5 TF ame: (b) When you consume oil or fat, your body releases the individual fatty acids from the triacylglyceride. Structures of two fatty acids are shown below. Indicate whether the carbon-carbon double bonds in each are in cis or trans conformations. H H (*extra*) These fatty acids are geometric isomers of each other. ne of them is a component of the "good fat" in olive oil, while the other is present in margarine and processed foods, and is thought to be detrimental to cardiovascular health. Can you guess which is which? (c) To release the fatty acids from the triacylglyceride, your body uses protein enzymes called lipases. ne step of the lipase-catalyzed reaction is shown below using arrowpushing formalism. C 17 H 33 lipase C 17 H 33 lipase How many electrons move during this process? In sentences, describe the movement of electrons; indicate where the electrons start out and where they end up. (*extra*) Why do you think the lipase oxygen forms a bond with the carbon atom shown? Why does it not form a bond with one of the oxygen atoms of the triacylglyceride? Why does it not form a bond with one of the other carbon atoms of the triacylglyceride?