Chemistry 14D Winter 2015 Exam 2B Page 1

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1 Chemistry 14D Winter 2015 Exam 2B Page 1 1. (12) Write the major organic product, best reactant(s) or best starting material in the boxes. Assume reagents above/below the arrows are in excess unless otherwise specified. Do not include any mechanism details. If no reaction occurs write NR. (a) OH (b) O 2 N Br 2, FeBr 3 (c) (d) O 3 O 2 Questions 2 and 3 refer to this reaction: + Molecule A Molecule B 2. (3) Complete this statement by writing 'A' or 'B' in the blank, then adding no more than ten words: Molecule is the major product because (5) Write the mechanism for the formation of the major product you selected. Label the ratedetermining step with rds. Page 1 score =

2 Chemistry 14D Winter 2015 Exam 2B Page 2 4. (10) Write a mechanism: 5. (3) This reaction provides a major product of molecular formula C 10 H 20 O 2. Write this major product in the box. 6. (6) If the water is omitted from the reaction in question 5, the product changes, as shown below. Write a mechanism for this reaction. Page 2 score =

3 Chemistry 14D Winter 2015 Exam 2B Page 3 7. (11) Write the mechanism for the following reaction. Label the rate-determining step as rds. AlCl 3 Cl benzene Questions 8 11 refer to this reaction of resorcinol (1,3-dihydroxybenzene): HO OH SO 3 H 2 SO 4 8. (3) In the space above, write the major product. 9. (2) If one of the OH groups of resorcinol is changed to a hydrogen atom, the reaction with SO 3 and H 2 SO 4 becomes (circle one): 10. (2) If one of the OH groups of resorcinol is changed to a methyl group, the reaction with SO 3 and H 2 SO 4 becomes (circle one): 11. (2) If one of the OH groups of resorcinol is changed to a nitro group, the reaction with SO 3 and H 2 SO 4 becomes (circle one): Page 3 score =

Chemistry 14D Winter 2015 Exam 2B Page 4 12.

4 Chemistry 14D Winter 2015 Exam 2B Page (3) Back in the days when the instructor of this course was a professor at another southern California university an undergraduate student in his research lab discovered the following electrophilic aromatic substitution reaction: NaNO 3, TiCl 4 CH 2 Cl 2 NO 2 Electrophile In the box above draw the Lewis structure of the electrophile that attacks the aromatic ring. Include all lone pairs and formal charges for this electrophile. If the electrophile has resonance show only the best resonance contributor. 13. (7) Write a mechanism: CH 2 CH 3 Cl 2, heat Cl CH 2 CH 3 Questions 14 and 15 refer to the reaction of superoxide with a portion of DNA, shown below. The wavy lines mean molecule beyond this point unimportant. 14. (4) In the space above write the curved arrows and mechanism step product derived from the reaction of superoxide with H a. 15. (4) Complete this statement by adding no more than fifteen words: Superoxide might abstract H b instead of H c because... (Hint: The answer is not steric hindrance.) Page 4 score =

5 Chemistry 14D Winter 2015 Exam 2B Page (3) Toluene is a common trace impurity in drinking water. By using enzymes such as cytochrome P-450, the body oxidizes toluene in order to make it more soluble and this easier to excrete. Toluene could be oxidized to form an epoxide or to form benzyl alcohol. Hint: You do not need to know anything about the reaction mechanism to provide a reasonable answer. CH 2 OH P-450 CH 3 P-450 CH 3 Benzyl alcohol Toluene Epoxide O Circle the more probable oxidation product above, then complete this explanation by adding no more than ten words: This is the major oxidation product because (3) Does nature use all of the carbocation fates in steroid biosynthesis? After each carbocation fate, write 'yes' in the blank if the fate is part of steroid biosynthesis from squalene, or 'no' if it is not. Capture a nucleophile: Be deprotonated; form a pi bond: Rearrange: 18. (3) Using no more than fifteen words, define antioxidant. Recall that an example is not a definition. 19. (4) In lecture we discussed several radicals that occur in organisms. Some of these radicals are beneficial, while others are not. Write the name or molecular structure of an appropriate radical in each blank. A beneficial (good) radical: A deleterious (damaging) radical: 20. (2) Draw in the box most stable radical possible having exactly five carbon atoms, and any number of any other elements. 21. (2) Draw the two structures (one per box) formed in the rate-determining step when HF adds to styrene (PhCH=CH 2 ). If only one structure is formed draw an X in the second box. 22. (3) Write a reaction (including all reactants and the major product) that illustrates anti addition (and only anti addition) to an alkene. Do not include any mechanism details. 23. (3) In the box write the number(s) of the exam question(s) that involve tautomerization. Include letters if the question has one, such as 46(q). If there are none write 'none' in the box. Page 5 score =

Electrophilic Aromatic Substitution Reactions

Electrophilic Aromatic Substitution Reactions, Course Notes Archive, 1 Electrophilic Aromatic Substitution Reactions An organic reaction in which an electrophile substitutes a hydrogen atom in an aromatic