The following exam contains 30 questions valued at 3 point/question and bonus opportunities. Name:

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1 Chemistry 261 Exam 3 all 2017 The following exam contains 30 questions valued at 3 point/question and bonus opportunities Name: ELECTROPILIC ADDITION REACTIONS BASIC REACTION OUTCOMES 1. Addition of hydrogen chloride to the following molecule would produce? I II III a. I & II b. II & III c. I & IV d. V e. All of the above are equally likely IV V ELECTROPILIC ADDITION REACTIONS BASIC REACTION OUTCOMES 2. What is/are the principal product(s) of the following reaction? 2, C 4? C 3 C 3 C 3 C 3 C 3 7 C 3 7 C 3 7 C 3 7 I II III a. Equal I & II b. Equal II & III c. Equal III & IV d. Major products I & II, minor products III & IV e. All of the above in equal amounts IV

2 ELECTROPILIC ADDITION REACTIONS MECANISM O ALOGENATION 3. The interaction of the alkene bond with an electrophile results in the formation of a species termed a complex. Which of the following cannot form a complex with an alkene? + a. (C 3 ) 3 b. C 3 c. B 3 d. 2 SO 4 e. Al 3 BONUS (3 EC) Given what you know about the addition of strong acids across double bonds, provide a plausible mechanism for the polymerization 2-methyl-1-butene in the presence of small amounts of ELECTROPILIC ADDITION REACTIONS IN DEPT REACTION OUTCOMES 4. If propene is treated with in the presence of sodium acetate, where the and sodium acetate are in equal concentrations, which of the following will form? 1 a. Isopropyl acetate b. Propyl acetate c. 1-bromopentane d. 2-bromopentane e. None of the above will form 1 A careful consideration of the relative pk a s of acetic acid and is required here

3 ELECTROPILIC ADDITION REACTIONS MECANISM O OXYMERCURATION/REDUCTION 5. What is the term that best describes function ofthe mercury(ii) acetate in the oxymercuration/reduction reaction sequence? a. Lewis acid b. Nucleophile c. Electrophile d. Leaving group e. Catalyst ELECTROPILIC ADDITION REACTIONS MECANISM O YDROBORATION/OXIDATION 6. What is the major product of the following reaction? a. B 3 :T a. b. 2 O 2, NaO O b. O + enantiomer c. O + enantiomer d. O + enantiomer e. More than one of the above

4 ALKENE TO ALCOOL PRODUCT OUTCOMES 7. What is the principal product formed when 3-methyl-1-butene is reacted with 2 O/ 2 SO 4? a. 3-methyl-1-butanol b. 3-methyl-2-butanol c. 3-methyl-3-butanol d. 2-methyl-2-butanol e. None of the above GENERATION O RADICAL SPECIES 8. Please list a specific reagent that will generate individual, uncharged bromine atoms when mixed with Reagent: RADICAL ADDITION TO ALKENE PRODUCT OUTCOME 9. Using the reagent you listed in question # 8, please show the reaction leading to isobutyl bromide from 2-methyl propene GENERAL ALKENE REACTIONS 10. ydroxylation of trans-2-pentene with cold alkaline KMnO 4 yields C 3 C 3 O C 3 C 3 O O O C 2 5 O O C 2 5 O C 2 5 C 2 5 O I II III IV a. Equal amount of I & II b. Equal amount of II & III c. Equal amounts of III & IV d. I & II as major products, III & IV as minor products e. All of the above in equal amounts

5 MULTISTEP SYNTESIS 11. What is the principal product formed when cyclohexanol is subjected to (1) conc. 2 SO 4 / followed by (2) O 3 (3) then aq. 2 O 2? 2 a. Cyclohexene b. cis-1,2-cyclohexanediol c. trans-1,2-cyclohexanediol d. cyclohexanedial (adipaldehyde) e. cyclohexanedioic acid (adipic acid) MULTISTEP SYNTESIS 12. What is the principal product formed when cyclohexanol is subjected to (1) conc. 2 SO 4 / followed by (2) O 3 (3) then (C 3 ) 2 S? a. Cyclohexene b. cis-1,2-cyclohexanediol c. trans-1,2-cyclohexanediol d. cyclohexanedial (adipaldehyde) e. cyclohexanedioic acid (adipic acid) TYPES O ISOMERISM 13. Enantiomers are a. Molecules that have a mirror image b. Molecules that have at least 1 stereogenic center c. Non-superimposable molecules d. Non-superimposable constitutional isomers e. Non-superimposable molecules that are mirror images of each other IDENTIICATION O PLANES O SYMMETRY AND CIRAL CENTERS 14. ow many chiral stereoisomers can be drawn for C 3 CCC(C 3 ) 2? a. 1 b. 2 c. 3 d. 4 e. 8 2 Recalling the condition dependent reversibility of alkene addition reactions would be very handy right about now

6 IDENTIICATION O PLANES O SYMMETRY AND CIRAL CENTERS 15. Which of the following molecules does not contain a plane of symmetry? C 3 I II C 3 III 3 C IV V a. I, II, & V b. I, III, & IV c. II, III, & IV d. III & IV e. V NAMING CIRAL COMPOUNDS 16. Which of the following represents (R)-1-Chloro-1-fluroethane? YAVW C 3 C 3 I II a. I b. II c. III d. More than one of the above e. None of the above C 3 III NAMING CIRAL COMPOUNDS 17. Please completely name the following compound according to IUPAC rules Name:

7 NAMING CIRAL COMPOUNDS 18. Please completely name the following compound according to IUPAC rules. Name: NAMING CIRAL COMPOUNDS 19. Please completely name the following compound according to IUPAC rules Name: PROPERTIES O CIRAL COMPOUNDS 20. The pair of compounds shown below would have C 3 C 3 C 3 3 C a. The same boiling point b. Different melting points c. Equal but opposite optical rotations d. More than one of the above e. All of the above PROPERTIES O CIRAL COMPOUNDS 21. Which of the following would discriminate between (R) and (S) enantiomers? a. Plane polarized light b. Boiling point c. Melting point d. Solubility in ( )-2-butanol e. More than one of the above

8 DETERMINATION O ENANTIOMERIC EXCESS 22. Compound X contains a single chiral center. If the pure (R) enantiomer of compound X has a specific rotation of o, what is the specific rotation of the pure (S) enantiomer, compound Y? a o b. 0 < S.R. Y < o c. 0.0 o d. 0 < S.R. Y < o e o DETERMINATION O ENANTIOMERIC EXCESS 23. Referring to the previous question, what is the specific rotation of a 2Y:1X mixture of the 2 enantiomers? a o b o c. 0.0 o d o e o DIERENTIATION O ENANTIOMERS, DIASTEREOMERS, AND MESO COMPOUNDS 24. Which of the following is a meso compound? a. I b. II c. III d. IV e. V C 3 O 3 C O C 2 O 2 C I O C 3 C 2 O C 2 O 3 C O II O C 3 III IV V C 2 O C 3 O

9 DIERENTIATION O ENANTIOMERS, DIASTEREOMERS, AND MESO COMPOUNDS 25. ow are the following compounds related? C 3 O O C 3 a. Diastereomers b. Enantiomers c. Constitutional Isomers d. Identical e. Not isomeric RESOLUTION O CIRAL COMPOUNDS 26. Which of the following will resolve a racemic mixture of (R,S)-2-butanol? a. ormation of a chiral salt by reaction with (2R,3R)-(+)-tartaric acid b. ormation of a chiral ester by reaction with (2R,3R)-(+)-tartaric acid, followed by ester hydrolysis c. ractional distillation d. None of the above racemates cannot be separated e. All of the above would resolve the 2 enantiomers ELECTROPILIC ADDITION REACTIONS STEREOCEMISTRY O 2 ADDITION 27. Disregarding the possibility of vicinal dibromide formation and counting stereoisomers separately, how many compounds are possible from the addition of 2 to trans-2-butene in an aqueous environment? a. 1 b. 2 c. 3 d. 4 e. 6

10 REVIEW: RESONANCE 28. Which of the following compounds is stabilized to the greatest extent by resonance? a. Phenol b. Sodium phenoxide c. para-nitrophenol 3 d. Sodium para-nitrophenoxide e. (b) and (d) are stabilized to the same extent REVIEW: CURVED ARROW APPROAC TO REACTION MECANISMS 29. Used the curved arrow approach to show the reaction between phenol and sodium hydroxide, including a depiction of resonance stabilization in the resulting conjugate base REVIEW: pk a s 30. Which of the following has the lowest pk a value? a. C 3 CO 2 b. IC 2 CO 2 c. C 2 CO 2 d. C 2 CO 2 e. C 2 CO 2 3 A nitro group is R-NO 2, with N bearing a positive charge and one of the oxygens bearing a negative charge, just like in nitric acid

11 BONUS (3 EC) ortho methoxy phenol (2-hydroxyanisole, guaiacol 4 ) has a pk a = 9.9 (very close to phenol), whereas ortho-fluorophenol has a pk a = 8.7. urther, 3-fluorophenol pk a = 9.3, and 4-fluorophenol pk a = 9.9, 2.5 pk a units higher than para-nitrophenol! a. What is the reason for the difference in pk a s between guaiacol and orthofluorophenol? b. What accounts for the difference in pk a s between the 3 fluorophenol isomers? 4 Guaiacol is found in wood smoke, isolated from wood creosote, and is a precursor to numerous flavorants, most notably vanillin (ca. 85 % of the world s supply of vanillin is derived from guaiacol. Vanillin is 4-hydroxy-3- methoxybenzaldehyde. Interestingly, or creepily, guaiacol is also generated in the gut of the desert locust upon consumption of plant material and acts as a swarming pheromone

12 c. Why doesn t the ortho-methoxy (methyl ether) group lower the pk a significantly when attached to phenol? BONUS SECTION Please list up to 5 valuable reactions you have learned in the course to date, and provide an example of each. Please list them in order of perceived value, with a brief indication of why you see the reaction as valuable. 2 points/question. Reaction 1: Example: Reason for Importance: Reaction 2: Example: Reason for Importance:

13 Reaction 3: Example: Reason for Importance: Reaction 4: Example: Reason for Importance: Reaction 5: Example: Reason for Importance: