ITOC-PS - it is a probset abt chem lec PDF

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it is a probset abt chem lec...

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INTRODUCTION TO ORGANIC CHEMISTRY PROBLEM SET Answer the following questions 1. Sinemet, the trade name of a drug used to treat Parkinson’s disease, contains a combination of L-dopa and carbidopa. Carbidopa increases the effectiveness of L-dopa by inhibiting its metabolism prior to crossing the blood–brain barrier and entering the brain. Answer the following question about L-dopa.

a. Convert the skeletal structure to a Kekulé structure. (Don’t forget the lone pairs) b. What is the hybridization and geometry around each highlighted atom? c. Label three polar bonds. 2. Vitamin B6 is beneficial to the central nervous system and metabolism. VB6 may improve mood and reduce symptoms of depression, and may promote brain health and reduce Alzheimer’s risk. Answer the following questions about VB6.

a. Draw a skeletal structure of vitamin B6 b. How many sp2 hybridized carbons are present? Encircle/highlight them. c. What is the hybridization of the N atom in the ring? Explain.

3. Citric acid is responsible for the tartness of citrus fruits, especially lemons and limes.

a. b. c. d. e.

What is the molecular formula for citric acid? How many lone pairs are present? Draw a skeletal structure. How many sp2 hybridized carbons are present? What orbitals are used to form each indicated bond ([1] – [4])?

4. Assign formal charges to each carbon atom in the given species. All lone pairs have been drawn in.

5. Draw an acceptable Lewis structure from each condensed structure, such that all atoms have zero formal charge. a. diethyl ether, (CH3CH2)2O, the first general anesthetic used in medical procedures b. acrylonitrile, CH2CHCN, starting material used to manufacture synthetic Orlon fibers c. dihydroxyacetone, (HOCH2)2CO, an ingredient in sunless tanning products d. acetic anhydride, (CH3CO)2O, a reagent used to synthesize aspirin

6. Creatine is a dietary supplement used by some athletes to boost their athletic performance.

a. Draw in all lone pairs in creatine. b. Draw two additional resonance structures showing all lone pairs and formal charges. 7. Draw Lewis structures for the nine isomers having molecular formula C3H6O, with all atoms having a zero formal charge.

8. With reference to compound A drawn below, label each compound as an isomer, a resonance structure, or neither.

9. With reference to cation B, label each species as an isomer, a resonance structure, or neither.

10. Draw a second resonance structure for each ion. Then, draw the resonance hybrid.

11. Consider compounds A–D, which contain both a heteroatom and a double bond.

a. For which compounds are no additional Lewis structures possible?

b. When two or more Lewis structures can be drawn, draw all additional resonance structures.

12. Consider the compounds and ions with curved arrows drawn below. When the curved arrows give a second valid resonance structure, draw the resonance structure. When the curved arrows generate an invalid Lewis structure, explain why the structure is unacceptable.

13. Draw four additional resonance structures for the following cation. Then draw the resonance hybrid.

14. How many hydrogens are present around each carbon atom in the following molecules?

15. Convert each skeletal structure to Kekulé structure.

16. Convert each molecule into a skeletal structure.

17. Draw in all the hydrogen atoms and nonbonded electron pairs in each ion....