72. The syntheses shown here are unlikely to occur as written. What is wrong with each? 

68. Which system would give the largest ratio of substitution to elimination product(s)? (A) cyclohexanol + acid (B) cyclohexyl iodide + t-BuOK in t-BuOH (C) 1-bromobutane + t-BuOK in DMSO (D) 1-bromobutane + KI in acetone (E) 2-bromobutane + MeONa in DMSO

69. Optically pure (S)-monosodium glutamate has a specific rotation of +25o , what percent of (R)-monosodium glutamate in a sample with a specific rotation of -10o ? (A) 10% (B) 30% (C) 40% (D) 70% (E) 50%

70. What reagents can be used to convert 1-hexyne into 2-hexanone? (A) 1. Sia2BH; 2. H2O2, NaOH (B) Hg2+, H2SO4, H2O (C) 1. O3; 2. (CH3)2S (D) 1. CH3MgBr; 2. CO2 (E) 1. H2, Ni; 2. Na2Cr2O7, H2SO4

71. Below is a propose a synthesis of compound A. Which step would not work. 

73. Which of the reactions below would not produce n-butylamine ?

74. Determine the product of the synthetic sequence below. 

75. A chiral C7H16O2 diol is oxidized by PCC in CH2Cl2 to an achiral C7H12O2 compound. Which of the following would satisfy these facts?

76. Which of the following molecules is chiral? 

77. Stereoisomers I and II undergo E2 elimination on treatment with sodium ethoxide in ethanol. One isomer reacts 500 times faster than the other. Also, one isomer gives X as the only product, whereas the other gives Y together with some X. Which of the following statements provides the best assignment of I and II?  (A) II reacts faster and gives both Y and X (B) II reacts faster and gives only X (C) I reacts faster and gives both Y and X (D) I reacts faster and gives only Y (E) I reacts faster and gives only X

78. What product is wrong when carvone is treated with the following reagents?