22. Which of the following descriptions of the nucleoside uridine does NOT apply to the structure of the molecule?
(A) The uracil base is directly bonded to the 1' position of ribofuranose in the α position.
(B) The ribofuranose moiety is found in only the D configuration.
(C) Nitrogen, at position 1 in the uracil base, is directly bonded to the ribofuranose moiety.
(D) The 5' OH group is replaced with phosphate(s) in the nucleotide structure.
(E) None of the above

18. Grignard reagents react with oxirane (ethylene oxide) to form 1o -alcohols but can be prepared in tetrahydrofuran solvent. Why is this difference in behavior observed? (A) Steric hindrance in the case of tetrahydrofuran precludes reaction with the Grignard. (B) There is a better leaving group in the oxirane molecule. (C) The oxirane ring is the more highly strained. (D) It is easier to obtain tetrahydrofuran in anhydrous condition. (E) Oxirane is a cyclic ether, while tetrahydrofuran is a hydrocarbon.

19. The regioselectivity and stereospecificity in the oxymercuration-demercuration of an alkene is best described as: (A) Markovnikov orientation with syn-addition (B) Markovnikov orientation with anti-addition (C) anti-Markovnikov orientation with syn-addition (D) anti-Markovnikov orientation with anti-addition (E)Markonikov orientation with both syn- and anti-addition

20. What is the major product of the following reaction?(A)(B)(C)(D)(E) None of the above.

21. What is the major product of the following reaction?  (A) I (B) II (C) III (D) IV (E) V

23. Which sequence ranks the following aromatic rings of this compound in order of increasing reactivity in an electrophilic aromatic substitution reaction (slowest to fastest reacting)?  (A) 3 < 2 < 1 (B) 2 < 3 < 1 (C) 2 < 1 < 3 (D) 1 < 3 < 2 (E) 1 < 2 < 3

24. Which sequence ranks the indicated protons in order of increasing acidity?  (A) 3 < 2 < 1 (B) 2 < 3 < 1 (C) 2 < 1 < 3 (D) 1 < 3 < 2 (E) 1 < 2 < 3

25. Which pair of structures represents the same compound? (A) I and II (B) II and IV (C) III and IV (D) III and V (E) IV and V

26. What is the major product of the following reaction?  (A) I (B) II (C) III (D) IV (E) V

27. What is the major product of the following reaction? (A) I (B) II (C) III (D) IV (E) V

28. Which of the following is the strongest nucleophile? (A) NaOH (B) NaOMe (C) KOH (D) KOMe (E) KSMe