CH Organic Chemistry I (Katz) Practice Exam #3- Fall 2013

Transcription

1 C rganic Chemistry I (Katz) Practice Exam #3- all 2013 Name: Score: Part I - Choose the best answer and write the letter of your choice in the space provided. (32 pts) 1. f the following, which reaction proceeds through syn addition? A) halogenation of an alkene with 2 and CCl4 B) conversion of an alkene to a bromohydrin with 2 and 2 C) hydration of an alkene by oxymercuration D) hydration of an alkene by hydroboration-oxidation 2. Na dissolved in ammonia is used for converting: A) alkyl halides to amines B ) alkynes to trans alkenes C) cis alkenes to trans alkenes D) alkynes to cis alkenes 3. The diagram at right represents A) The final step in an E1 reaction B) The rate-limiting step in an E2 reaction C) The rate limiting step in an SN1 reaction D) The final step in an SN2 reaction Base 4. As a class of hydrocarbons, terminal alkynes are distinctive among hydrocarbons because: A) their terminal hydrogens are the most acidic hydrogens of all classes of hydrocarbons B) they react with 2 in CCl4 via a syn addition C) they are the least thermodynamically stable of all classes of hydrocarbons D) they do no react with B3 in T 5. Which of the following sets of conditions would most likely produce an enantiomerically pure product through complete inversion at a chiral center? A) reaction of strong base with a secondary alkyl iodide in methanol B) reaction of a weak base with a tertiary alkyl iodide in water C) reaction of a strong nucleophile with a primary alkyl bromide in DMS D) reaction of a strong nucleophile with a secondary alcohol in water

2 6. and represent A) conformational isomers B) diastereoisomers C) constitutional isomers D) tautomers 7. Which are the contaminants which produce anti-markovnikov products in hydrohalogenations? A) excess acids or bases B) radicals C) communists D) liberals 8. f the following compounds, E C 3 I Z Cl 3 C Z E C 2 3 C C 2 C 3 I C 2 C 3 C 3 the total number of E isomers represented is: A) 4 B) 3 C) 2 D) 1 9. The rate-determining step in the hydration of an alkene is: A) addition of - to the carbocation B) loss of a proton C) rearrangement of the product to form the Markovnikov isomer. D) carbocation formation 10. The incorrect IUPAC name among the following is: A) 4-methylcyclobutene B) 5-bromo-2-chloro-2-hexene C) 3-ethyl-3-hexene D) 3,4-dimethylcyclopentene 11.Which compound is the major organic product of the following reaction? C 3? A B C D

3 12. Which set of reagents would give the given product for this reaction? A) 1. g(ac)2 in T/2 followed by 2. NaB4 B) 1. B3, 2. 22, -, 3. Na, 4. C3C2C2I C) 1. g(ac)2 in T /2 followed by 2. C3C2C2 D) 1. B3, 2. 22, Which compound is not a possible product from addition of 2 to 1-butyne? A B C D 14.Addition of 2 to cyclopentene would give a product which is A) achiral B) racemic C) meso D) optically active Which of the following alkynes could be used to make this ketone selectively? A B 16. The following reaction does not proceed to yield the indicated substitution product: I + C C C 3 X Which product is produced? A B C D

4 Part II-Provide IUPAC names for the following molecules. Don't forget to indicate stereochemistry when applicable (i.e R or S, cis or trans). ( 12 pts ) 17. Cl C Cl (E)-2,3-dichloro-2-hexene (S)-4,5-dimethyl-2-hexyne 19. 1,5,5-trimethylcyclopentene Part III-Draw structures for the following molecules. ( 12 pts ) 20. (Z)-3-isopropyl-2-hexene 21. 3,6-difluoro-4-isopropyl-1-heptyne 22. 1,3-dibromo-4-ethylcyclohexene

5 Part IV - Draw a detailed mechanism for the following hydration reaction, providing the structures of all relevant intermediates and indicating any movement of electrons, hydrogens, or methyl groups with curved arrows ( 14 pts) Part V - The following alkene reacts with 2 to give two stereoisomers. Complete the structures of the two products and give them complete systematic names ( 12 pts ) C 3 C 2 C C(C 3 ) 2 2 C(C 3 ) 2 3 C C 2 C 3 3 C C 2 C 3 C(C 3 ) 2 (3R,4R)-3,4-dibromo-2,4-dimethylhexane (3S,4S)-3,4-dibromo-2,4-dimethylhexane

6 Part VI - Propose a synthetic scheme (a sequence of reactions) which will yield the given product from the indicated starting material. You may utilize any common organic or inorganic reagents. (16 pts) C 3 I 2 eq base NaN C C 3 acid,heat 3 C C 3 RC 1 eq base