CHEM 2311 E2 practice-ii (answers provided) YOU MAY USE A SMALL MODEL KIT ON THIS EXAM 1. (32 points) Circle the letter on the right which corresponds to the answer to each question. There is only one correct answer for each question. (i) What is the correct IUPAC name for the following structure? A. 3,5-dimethyl-2,4-diethylheptane B. 2,5-diethyl-4-methylheptane C. 3-ethyl-4,6-dimethyloctane D. 6-ethyl-3,5-dimethyloctane (ii) What is the correct IUPAC name for the following structure? E. 1,2-diethyl-4-methyl-1-pentanol F. 4-ethyl-5-hydroxy-2-methylheptane G. 4-ethyl-5-methyl-3-heptanol H. 4-ethyl-2-methyl-5-heptanol (iii) Which of the following represents the lowest energy conformation of 2,3-dimethylbutane? I J K L (iv) Which of the following represents the lowest energy conformation of trans 1,3-dimethylcyclo-hexane? M N O P For parts (v) – (viii), consider compounds 1, 2, 3 and 4 (v) What is the relationship between compounds 1 and 2? Q. identical R. enantiomers S. diastereomers T. constitutional isomers (vi) What is the relationship between compounds 1 and 3? U. identical V. enantiomers W. diastereomers X. constitutional isomers (vii) What is the relationship between compounds 1 and 4? Y. identical Z. enantiomers AA. diastereomers BB. constitutional isomers (viii) Which compounds (1-4) rotate plane polarized light? CC. none of them DD. only 1 and 4 EE. only 2 FF. 1, 2, 3 and 4 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA BB CC DD EE FF H3COHHCH3OHHH3CCH3OHH OHHHOHCH3H CH3HOCH3CH3OHHOHH1234H3CCH3HCH3HH3CHHCH3CH3CH3H3CH3CCH3HCH3CH3HH3CHHCH3HHOH2. (32 points). (a) (8 points) Compound A, C6H10, rotates plane polarized light. Hydrogenation of A gives B, C6H12. Provide structures of A and B consistent with this data. (b) (8 points) Draw line-bond structures of the following compounds (c) (8 points) Draw the most stable chair conformation of the following compounds (d) (8 points) Provide the value of SODAR (hydrogen deficiency index) of the following two molecular formulas. C6H12BrNO2 C7H10O3 (ii) trans 1-tert-butyl-3-methylcyclohexane (i) trans 1-isopropyl-2-methylcyclohexane (i) bicyclo[3.2.0]heptane B A (ii) 4-bromo-5-methyl-2-cyclohexenol3. (36 points). (a) (4 points) Place the remaining substituents on the Fischer projection to accurately represent the stereoisomer shown. (b) (5 points) Place the remaining substituents on the Newman projection to accurately represent the stereoisomer shown. (c) (10 points) The specific rotation, [α], of the pure S enantiomer of compound C is -50°. A student prepared a mixture of R and S enantiomers of C. She took 0.2 g of the mixture, dissolved it in 1.0 mL of chloroform and measured an optical rotation of +5° in a 10 cm polarimeter tube. (i) Which enantiomer is in excess in the mixture? (ii) What is the %ee of the mixture? % (iii) What mass of the S enantiomers is present in 100 g of the mixture? (d) (8 points) Assign the R/S configurations to the stereogenic centers in the following two molecules (e) (9 points) How many stereoisomers exist for each of the following compounds? (i) 2-methyl-2-pentanol (ii) 3-methyl-2-pentanol (iii) 4-methyl-2-pentanol