68. The HOMO of (2E,4Z,6E)-octatriene undergo thermal cyclization using which process and which product? (HOMO orbital of pi-electrons of octatriene is given below, not showing the stereochemistry) 
(A) disrotatory and cis-product
(B) conrotatory and cis-product
(C) disrotatory and trans-product
(D) conrotatory and trans-product
(E) both disrotatory and conrotatory to give trans and cis product respectively

64. Predict the major product of the following reaction sequence. (A)(B)(C)(D)(E)

65. What is the relative reactivity of 2° vs 1° hydrogens in the free radical bromination of n-butane if the ratio of 1-bromobutane to 2-bromobutane formed is 7:93? (A) The 2° hydrogens are 20 times more reactive than the 1° ones. (B) The 2° hydrogens are 40 times more reactive than the 1° ones. (C) The 2° hydrogens are 60 times more reactive than the 1° ones. (D) The 2° hydrogens are 80 times more reactive than the 1° ones. (E) The 2° hydrogens are 100 times more reactive than the 1° ones.

66. Which sequence of reagents works best to convert 1-methyl-1-vinylcyclohexane to E-1-methyl-1-(prop-1-en-1-yl)cyclohexane? ? (A) 1. NaOCH3, CH3OH 2. NaNH2 3. Br2 4. H2 (excess), Pd/C (B) 1. Br2 2. NaNH2 3. NaNH2, then CH3Br 4. Na, NH3 (C) 1. BH3*THF 2. Br2 3. NaCN 4. Na, NH3 (D) 1. NaCN 2. HO- , H2O2 3. NaNH2, then CH3Br 4. Na, NH3 (E) 1. BH3*THF 2. Br2 3. NaNH2, then CH3Br 4. H2 (excess), Pd/C

67. How many of these reagents cause only syn additions to alkenes? HBr H2, Pd BH3 H2O2 CH3CO3H Br2 Hg(OAc) 2 (A) 1 (B) 2 (C) 3 (D) 4 (E) 5

複選題69. Assuming kinetic conditions, provide a structure for the major product of the reaction below. Include correct stereochemistry. ?  (A) I (B) II (C) III (D) IV (E) V

70. Predict the major product of the following reaction. OH CHO OH acid cat. ? (A)  (B)(C) (D)  (E)

71. Identify the monomer(s) which are used to prepare the following segment of polymer: - CH2CH=CHCH2CH(C6H5)CH2CH2CH=CHCH2CH(C6H5)CH2- (A) CH2=CH2 and CH2=CHC6H5 (B) CH2=CHCH=CH2 and CH2=CHC6H5 (C) CH2=C(C6H5)CH=CH2 (D) C6H5CH=CHCH=CH2 (E) CH2=C=CH2 and CH2=CHC6H5

72. What is the major product for the following reaction (A) (B) (C) (D)  (E) 

73. Which is the best procedure for the preparation of 2,4-dinitrobenzoic acid from benzene? (A) 1. HNO3/H2SO4 2. CH3Br/AlCl3 3. HNO3/H2SO4 4. KMnO4/H+ (B) 1. CH3Br/AlCl3 2. HNO3/H2SO4 3. KMnO4/H+ 4. HNO3/H2SO4 (C) 1. CH3Br/AlCl3 2. KMnO4/H+ 3. HNO3/H2SO4 (excess) (D) 1. HNO3/H2SO4 2. CH3Br/AlCl3 3. KMnO4/H+ 4. HNO3/H2SO4 (E) 1. CH3Br/AlCl3 2. HNO3/H2SO4 (excess) 3. KMnO4/H+

74. Predict the major product for the following reaction. (A) I (B) II (C) III (D) IV (E) II & IV