19, In the following reactions, which is the correct major product?
(A)
(B)
(C)
(D)
(E)

20. Starting with benzene, the best method for preparing para-nitrobenzoic acid is: (A) HNO3/H2SO4； then CH3CI/AlCl3； then separation of isomers； then KMnO4/-OH/heat, followed by H3O+. (B) CH3CI/AICl3； then HNO3/H2SO4； then separation of isomers； then KMnO4/-OH/heat, followed by H30t. (C) CH3CI/AICl3； then KMn04/-OH/heat, followed by H3O+； then HNO3/H2SO4. (D) HNO3/H2SO4； then KMnO4/-OH/heat, followed by H3O+； then CH3CI/AICl3. (E) HNO3/H2SO4； then CO2, followed by H3O+.

21. Rank the aromaticities of the following compounds from most stable to least stable. (i) thiophene (ii) benzene (iii) pyrrole (iv) furan (A) ii＞i＞iii ＞iv (B) ii＞iv＞iii＞i (C) ii＞iv＞i＞iii (D) ii＞iii＞iv＞i (E) iv＞ii＞i＞iii

22. Which of the following is true about the Witting reaction? (A) The formation of carbon-carbon double bond from carbonyl compounds (aldehydes and ketones) and triphenylphosphite is known as the Witting reaction. (B) The Horner-Wadsworth-Emmons reaction is a variation of the Witting reaction. The major is usually the (Z)-alkene isomer. (C) The Horner-Wadsworth-Emmons reaction involves use of a phosphonate ester instead of a triphenylphosphonium salt. (D) A cis oxaphosphetane intermediate is formed to produce a ( E )-alkene in the Wittig reaction. (E) All of these choices.

23. List of the following acid derivatives from most reactive carbonyl to least reactive carbonyl toward Grignard reagent. (i) acid chloride (ii) carboxylic acid (iii) acid anhydride (iv) amide (v) ester. (A) ii＞v＞iv＞iii＞i (B)i＞iii＞v＞ii ＞iv (C) i＞iii＞v＞iv＞ii (D) iii＞i＞v＞iv＞ii (E) iii＞i＞v＞ii＞iv

24. Malonic ester (diethyl malonate) is treated successively with sodium ethoxide (1 eq.), ethyl bromide, potassium tert-butoxide, isobutyI chloride, hot aqueous NaOH, HCI, and heat. What is the final product? (A) 4-Ethyl-2-methylpentanoic acid (B) 6-Methylheptanoic acid (C) 2-Ethyl-3-methylpentanoic acid (D) 2-Ethyl-4-methylpentanoic acid (E) EthylisobutyImalonic acid

25. Arrange the compounds below in an order of increasing basicity.                                     (A) ii＜ii＜i＜v＜iv (B) i＜v＜ii＜iii＜iv (C) i

26. When an equimolar mixture of ammonia and butyI bromide reacts, which of these products will form? (A) Butylamine (B) Dibutylamine (C) Tributylamine (D) Tetrabutylammonium bromide (E) All of these choices.

27. What would be the correct order of adding reagents (i)~(v), for the formation of the desired product? (A)v→ii→iv→i→ii  (B)v→iv→i→ii→ii  (C)v→i→iii→iv＞ii(D)v→i→ii→iii→iv (E)i→iii →iv→v→ii 

28. Which of the following carbohydrate structure is the cyclized form of the hexose in Fischer projection? (A)(B)(C) (D)(E)

29. Which of the major product in the following transformations is incorrect? (A)(B)(C) (D)(E)

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