Chapter 5.4, Problem 18ATS

4 What are enantiomers? What instrument can you use to distinguish the enantiomers? What is racemic mixture? What is enantiomeric excess (e.e)? 5 For a chiral compound with 2 chiral centers how many configurations (also called isomers in lose sense) are possible. Use 2¹ rule. 6 Pure (R)- lactic acid has rotation of + 12.31º. A mixture of lactic acid has a specific rotation of +2.71º. Determine the percent composition of two enantiomers (R) and (S) in the mixture.

3. A solution of enantiomers has an observed specific rotation of +8.0°ml/g dm and pure (+) enantiomer has a specific rotation of +12'ml/g dm. Determine the optical purity and ratio of the enantiomers in the mixture.

3. The specific rotation of (S)-carvone is +61°. A chemist prepared a mixture of (R)-carvone and its enantiomer, and this mixture had an observed rotation of -50°. A. What is the specific optical rotation of pure (R)-carvone? B. Calculate the %ee of this mixture. C. What percentage of this mixture is (S)-carvone?

5. The specific rotation of (S)-2-iodobutane is +15.90°. Draw the structure of (S)-2- iodobutane, predict the specific rotation of (R)-2-iodobutane, and determine the percentage composition of a mixture of (R)- and (S)-2-iodobutane with a specific rotation of -7.95°.

A solution prepared by mixing 10 mL of a 0.10 M solution of the R enantiomer of a compound and 30 mL of a 0.10 M solution of the S enantiomer was found to have an observed specific rotation of +4.8. What isthe specific rotation of each of the enantiomers? (Hint: mL * M = millimole, abbreviated as mmol)

8. The specific rotation of (S)-carvone (at +20°C) is +61. A chemist prepared a mixture of (R)-carvone and its enantiomer, and this mixture had an observed rotation of -55°. (a) What is the specific rotation of (R)-carvone at 20°C? (b) Calculate the % ee of this mixture. (c) What percentage of the mixture is (S)-carvone?

The specific rotation of (S) butanol is +13.5 if 1.00g of its enantiomer is dissolved in 10.0mL of ethanol and placed in a sample cell with a length of 1.00 dm, what observed rotation do you expect?

7. a) Identify all the chiral/stereogenic centres in the following molecules. Circle the chiral carbon(s). OH CI -Br CI ОН O,N CI Br CI CI A B OH HO, .CI Br HO OH b) For each chiral center, prioritize the groups (1-4) attached to each chiral center(s) Based on your priorities, assign R or S configurations to the chiral center(s). i) Но ii) H2N H ОН но OH iv) OH OH v) H,N- ČH,OH Draw the most stable chair conformation for each of the following cyclohexanes. Now, "flip" the ring and redraw the molecule in the higher energy form. i) chlorocyclohexane ii) cis-1-chloro-2-methylcyclohexane iii) trans-1-methyl-3-propylcyclohexane

Calculate  the specific rotation of each isomer  in a mixture  containing 10 mL (0.10M) of the S enantiomer and 30 mL (0.10M) of R enantiomer . Given the specific rotation  of mixture =+4.8