Chemistry 261 Quiz 4, Take Home Fall 2017 Out: 12/04/17 Due: 12/06/17 (6 pm)

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1 Chemistry 261 Quiz 4, Take ome Fall 2017 Out: 12/04/17 Due: 12/06/17 (6 pm) The following cumulative quiz contains 52 questions valued at ¾ point/question and reflects Thursday s 150 point final exam, which will also contain 52 questions (at 3 points/question). Both quiz and exam cover the first 7 chapters in Loudon and Parise s Organic Chemistry, 6 th ed. Name: DISTRIBUTION OF VALENCE ELECTRONS, FORMAL CARGE 1. What is the charge on oxygen with 3 bonds and a single pair of non-bonded electrons? a. -2 b. -1 c. 0 d. +1 e. +2 LEWIS STRUCTURES (& BASIC NOMENCLATURE) 2. Please draw the complete Lewis structure for the citric acid cycle intermediate fumaric acid ((2E)-But-2-enedioic acid).

2 LEWIS STRUCTURES AND FORMAL CARGES 3. In which of the following compounds does the central atom have a formal charge = 0? a. b. F c. 3 C O C 3 F F B F d. F 3 C N C 3 e. None of the above ELECTRONEGATIVITY, POLARITY, AND DIPOLE MOMENTS 4. Which of the following common solvents has the smallest dipole moment? a. Chloroform, CCl 3 b. Acetone, (C 3 ) 2 CO c. Dimethylsulfoxide, DMSO, (C 3 ) 2 SO d. Acetonitrile, C 3 CN e. Methanol, C 3 O MOLECULAR GEOMETRY 5. The bond angle for the C-C-N bond in acetonitrile (C 3 CN) is expected to be? a. 90 o b. 109 o c. 120 o d. 145 o e. 180 o

3 YBRIDIZATION & MOLECULAR GEOMETRY 6. The lone pair of electrons in pyridine are contained in what type of orbital? N a. 2sp 2 b. 2sp 3 c. 2p d. 2s e. 2sp CURVED ARROW METOD AND RESONANCE 7. Using the curved arrow approach, please show the deprotonation of diethylmalonate by sodium hydride, followed by the principal contributing resonance structures, using the curved arrow approach to move from one form to the other CURVED ARROW METOD AND RESONANCE 8. Which of the following is not a resonance form of the boxed cationic compound shown? SC 3 SC 3 SC 3 SC 3 SC 3 I II a. I b. II c. III d. IV e. N/A; All are legitimate resonance structures III IV

4 STABILITY/RELATIVE CONTRIBUTION OF RESONANCE FORMS 9. Upon heterolytic decomposition 1 to the boxed cationic compound shown, which of the following forms contributes most to the overall hybrid? SC 3 SC 3 SC 3 SC 3 SC 3 a. II I II III IV b. III c. IV d. The boxed compound e. All contribute equally ATOMIC ORBITALS, MOLECULAR ORBITALS, & YBRIDIZATION 10. According to molecular bonding theory, in the case of a carbon-carbon double bond, the carbon-carbon bonding electrons of highest energy occupy which molecular orbital? a. bonding MO b. bonding MO c. * antibonding MO d. * antibonding MO e. * bonding MO 1 eterolytic decomposition removes both electrons in a bond to one of the bonding atoms, unlike homolytic cleavage to form radical species. Envisioning a chloro group at the site of the carbocation in the boxed compound may be helpful; such a molecule would be especially susceptible to S N 1 type reactions due to the resonance and carbon substitution shown

5 NEUMAN PROJECTIONS AND CONFORMATIONAL ANALYSIS 11. Which staggered Newman projection(s), looking down the C2-C3 bond (C2 in front, C3 in back) is consistent with the boxed compound shown? O 3 C C 3 O C=C 2 3 C C 3 O C=C 2 I 3 C O C 3 C=C 2 II III C 3 C 3 C 3 C 3 O O C=C 2 IV C=C 2 V a. I, II, & V b. II & V c. III & IV d. V only e. None of the above CLASSIFICATION OF CARBON CONNECTIVITY 12. ow many tertiary carbons exist in (1R,2S)-1,2-dimethylcyclopentane? a. 0 b. 1 c. 2 d. 3 e. 4

6 FUNCTIONAL GROUPS, NOMENCLATURE AND REPRESENTING MOLECULES 13. Please draw the bond-line structure for (Z)-3-phenyl-2-buten-1-ol FUNCTIONAL GROUPS, NOMENCLATURE AND REPRESENTING MOLECULES 14. Please draw the bond-line structure for para-(1-methylpropyl)-styrene (para-secbutyl-vinylbenzene) INTERMOLECULAR FORCES & PYSICAL PROPERTIES 15. Which of the following would have the poorest solubility in hexane? a. Acetone b. Isopropyl alcohol c. Propanoic acid d. Sodium propanoate e. Benzene ELECTRON DEFICIENT COMPOUNDS AND LEWIS ACID-BASE DEFINITIONS 16. Which of the following is not a Lewis acid? a. 3 O + b. 2 O c. BF 3 + d. PhC 2 e. N/A; all of the above are Lewis acids

7 NUCLEOPILES, ELECTROPILES, AND LEAVING GROUPS 17. Which of the following is the poorest leaving group? a. - b. C 3 O - c. 2 O d. O - e. N 3 BRØNSTED-LOWRY ACIDS AND BASES CONJUGATE ACID AND BASE DEFINITION 18. In the following equilibrium, which species act as Brønstead-Lowry bases? PO O PO O - a. PO and PO 4 b. PO -3 4 and O - c. PO -3 4 and 2 O d. 2 O and O - -2 e. 2 O and PO 4 FUN WIT pk a s 19. Which of the following contains a hydrogen of pk a 10-11? a. C 3 C 2 C 2 C 2 CO 2 b. PhO c. C 3 C 2 C 2 C C d. C 3 C 2 C 2 C 2 N 3 Cl e. More than one of the above FREE ENERGY AND CEMICAL EQUILIBRIUM 20. In what way does the acidity constant K a differ from the equilibrium constant K eq when the acid in question is placed in water under the same pressure, temperature, and concentration conditions? a. K a can be determined less accurately than K eq b. K a is used for strong acids only; K eq for weak acids c. K a is the reciprocal of K eq d. K eq = K a /[ 2 O] e. K a = K eq /[2O]

8 STRUCTURE-ACIDITY RELATIONSIPS 21. For each of the following compounds, rank the indicated hydrogen from most acidic to least acidic CO 2 C 3 O O N N I II III IV V O a. I > IV > II > V > III b. II > IV > I > V > III c. II > IV > V > I > III d. IV > I > II > V > III e. IV > II > I > V > III STRUCTURE-ACIDITY RELATIONSIPS 22. Rank the bold-faced hydrogens in the following compounds from most acidic to least acidic. O O C 3 O O I II III IV V a. III > IV > I > V > II b. II > III > V > IV > I c. II > V > III > IV > I d. V > III > II > IV > I e. III > I > IV > V > II

9 ACID-BASE REACTION PRODUCT PREDICTION CURVED ARROW APPROAC 23. What is/are the product(s) of the following acid-base reaction? O Li N a. b. O Li + + (C 3 ) 2 N C 3 Li O N c. O + (C 3 ) 2 N d. O + (C 3) 2 N Li e. None of the above STRUCTURE AND BONDING IN ALKENES 24. Which of the following is not a characteristic of an alkene bond? a. 90 o and 180 o bond angles b. Planarity c. Restricted rotation about the p bond d. The ability to participate in resonance if conjugated e. More than one of the above

10 DOUBLE BOND STEREOISOMERS/CIS-TRANS & E,Z NOMENCLATURE 25. Please draw the structure for (2E,4E)-hexa-2,4-dienoic acid UNSATURATION NUMBER OR INDEX OF YDROGEN DEFICIENCY 26. What is the unsaturation number for trans-decalin (bicyclo[4.4.0]decane)? a. 0 b. 1 c. 2 d. 3 e. 4 PYSICAL PROPERTIES OF ALKENES 27. Which of the following has the greatest solubility in water? a. Styrene (vinylbenzene) b. Cumene (isopropylbenzene) c. Phenylacetone (2-phenylpropanone) d. (E)-4-amino-3-phenyl-3-buten-2-one e. All have less than a 1.0 % v/v 2 O solubility

11 RELATIVE STABILITIES OF ALKENE ISOMERS 28. What is the major product for the following reaction sequence? 1. EtO, EtONa, heat a. Cl 2a. B 3 :TF 2b. 2 O 2, NaO b. O + enantiomer c. O + enantiomer d. O e. An equal mixture of (b) & (c) ADDITION OF YDROGEN ALIDES/CARBOCATION STABILITY/CARBOCATION REARRANGEMENTS 29. Isoprene (2-methyl-1,3-butadiene) forms 2 products when treated with Cl. The major product is 3-chloro-3-methyl-1-butene. The minor product is 1-chloro-3-methyl- 2-butene. Using resonance and a curved arrow approach, explain this finding

12 REACTION RATE CONSIDERATIONS 30. Referring to the previous question, which of the products should form by the lowest energy pathway? Which of the products is most stable? ow do you think it might be possible to change the ratio of the 2 to favor 1-chloro-3-methyl-2-butene? Lowest energy path: Most stable product: Method to change the ratio to favor 1-chloro-3-methyl-2-butene: CATALYSIS/CATALYTIC YDROGENATION OF ALKENES 31. Which of the following will convert 1-butyne to 1-butene? a. 2 + Pd/C b. 2 + Pd/CaCO 3 + Pb(OAc) 2 + quinoline c. 2 + Raney Ni d. O 3, followed by (C 3 ) 2 S e. More than one of the above ELECTROPILIC ADDITION REACTIONS BASIC REACTION OUTCOMES 32. ow many products are formed when Br 2 reacts with 2,3-dimethylbutene? a. 0 b. 1 c. 2 d. 3 e. 4

13 ELECTROPILIC ADDITION REACTIONS MECANISM OF OXYMERCURATION/REDUCTION 33. What is the principal product observed when 1-butyne is treated with aqueous mercuric acetate, followed by reduction with a mixture of sodium borohydride and sodium hydroxide? int: A tautomerization occurs following initial borohydride reduction a. b. c. d. e. (c) and (d) in equal amounts ELECTROPILIC ADDITION REACTIONS MECANISM OF YDROBORATION/OXIDATION 34. Why does borane react with alkenes in a 1:3 ratio a. Borane has 3 empty orbitals available b. Borane has 3 hydrogens available c. In losing hydrogen as hydride after the initial reaction, an additional empty orbital is made available on the boron d. After the initial addition, the alkyl boron is susceptible to direct nucleophilic attack by another alkene e. None of the above correctly explains the above ratio

14 ALKENE TO ALCOOL PRODUCT OUTCOMES 35. Which of the following would convert an alkene to an alcohol, with or without the presence of other functional groups? a. Treatment of the alkene with aqueous 2 SO 4 b. Treatment of the alkene with aqueous Br 2 c. Treatment of the alkene with O -78 o C, followed by C 3 SC 3, followed by treatment with NaB 4 (no NaO) d. More than one of the above e. All of the above ELECTROPILIC ADDITION REACTIONS IN DEPT REACTION OUTCOMES 36. Unknown compound X was found by mass spectrometric accurate mass determination to have molecular formula C On catalytic hydrogenation, 1 mol of X absorbs 1 mol of hydrogen yielding a compound with the molecular formula C On ozonolysis and subsequent treatment with zinc and acetic acid, X yields only 6-oxo-heptanal. Which of the following is compound X? I II III a. I b. II c. III d. IV e. V IV V GENERATION OF RADICAL SPECIES 37. Which of the following is least likely to generate radicals upon exposure to UV EMR? a. F 2 b. 2 O 2 c. C 3 C 3 d. (C 3 ) 2 CC(C 3 ) 2 e. (C 3 ) 3 COOC(C 3 ) 3

15 RADICAL ADDITION TO ALKENE PRODUCT OUTCOME 38. Which of the following would be the most likely radical intermediate produced if 2,2- dimethylpentane is treated with Br in the presence of AIBN? a. b. c. d. e. (a) and (b) are equally likely TYPES OF ISOMERISM 39. I & II are O O Cl O O Cl I II a. Constitutional isomers b. Enantiomers c. Diastereomers d. Identical e. Not isomeric

16 IDENTIFICATION OF PLANES OF SYMMETRY AND CIRAL CENTERS 40. ow many stereogenic centers are found in the molecule adamantane? a. 0 b. 1 c. 2 d. 3 e. 4 NAMING CIRAL COMPOUNDS 41. The Cahn-Ingold-Prelog stereochemical designations for the isomer of 1,1,2,4- tetrachlorocyclopentane shown are Cl Cl Cl Cl a. 2R,4S b. 2S,4R c. 2R,4R d. 2S,4S e. The R,S designation does not apply here PROPERTIES OF CIRAL COMPOUNDS 42. The pair of compounds shown below would have C 3 F C 2 C 3 C 2 C 3 C 3 F I II a. the same melting point b. different boiling points c. equal but opposite optical rotations d. more than one of the above e. all of the above

17 DETERMINATION OF ENANTIOMERIC EXCESS 43. Pure L-phenylalanine has a specific rotation of o. What is the enantiomeric excess of a 10.0 g/ml solution of phenylalanine which when placed in a standard 1.00 dm cell and analyzed in a polarimeter rotates plane polarized light o? Enantiomeric excess: DIFFERENTIATION BETWEEN ENANTIOMERS, DIASTEREOMERS, AND MESO COMPOUNDS 44. The 2 compounds shown are Br Br Br and Br a. Identical b. Enantiomers c. Diastereomers d. Conformational isomers e. Meso forms DIFFERENTIATION OF ENANTIOMERS, DIASTEREOMERS, AND MESO COMPOUNDS 45. The 2 compounds shown are C 3 C 3 F F 2 N C 3 3 C F F N 2 a. Constitutional isomers b. Enantiomers c. Diastereomers d. Identical e. None of the above applies

18 RESOLUTION OF CIRAL COMPOUNDS 46. Knowing hydrogenation occurs at a single face to a bond, you have decided to reduce pyruvic acid (2-ketopropanoic acid) via hydrogenation in an attempt to synthesis L- lactic acid, just as L-lactate dehydrogenase does. Upon workup, much to your dismay you find your product does not appear to rotate plane polarized light. Briefly (but specifically, and a figure may help) what went wrong? ELECTROPILIC ADDITION REACTIONS STEREOCEMISTRY OF Br 2 ADDITION 47. Counting stereoisomers separately, how many compounds are possible from the addition of Br 2 to 3-methylcyclohexene in an aqueous environment? a. 2 b. 4 c. 6 d. 8 e. 10

19 STABILITY OF CYCLIC ALKANES 48. Which of these C isomers is most stable? I II III a. I b. II c. III d. IV e. V IV V CYCLOEXANE CONFORMATIONAL ANALYSIS 49. Which of the following is expected to be the most stable? a. cis-1,2-diphenylcyclohexane b. trans-1,3-diphenylcyclohexane c. cis-1,4-diphenylcyclohexane d. trans-1,4-diphenylcyclohexane e. All of the above are equally stable NAMING BICYCLIC COMPOUNDS 50. Please provide the IUPAC name for the following compound Name:

20 REACTIONS OF STEREOISOMERS 51. Noting S N 2 reactions proceed with an inversion of configuration, the major product(s) of the following reaction is(are) C 2 Cl O C 3 S N 2 3 C C 2 O C 3 C 2 O I II C 2 Cl O C 3 III a. I b. II c. III d. IV e. Equal amounts of I and II YDROGENATION STEREOCEMICAL OUTCOME IV O C 2 Cl 52. What is/are the products formed when (E)-3,4-dimethyl-3-hexene is subjected to hydrogenation conditions on a platinum surface? a. 1:1 (3S,4S)-3,4-dimethylhexane and (3R,4R)-3,4-dimethylhexane b. 1:1 (3R,4S)-3,4-dimethylhexane and (3S,4R)-3,4-dimethylhexane c. (3S,4S)-3,4-dimethylhexane alone d. (3R,4R)-3,4-dimethylhexane alone e. All of the above in equal proportions