Chemistry Exam 3: Reactions and Mechanisms in Organic Chemistry (CHEM 2261/01, Summer 08), Exams of Organic Chemistry

Download Chemistry Exam 3: Reactions and Mechanisms in Organic Chemistry (CHEM 2261/01, Summer 08) and more Exams Organic Chemistry in PDF only on Docsity! "Grade or Education" = 1 CHEM 2261/01 Summer 08 Exam 3 Chapters 7-9 1. Find the substitution product(s) of the reaction of (2S,3R)-2-chloro-3-methylpentane + high concentration of CH3O- from among the numbered structures shown below. Choose the CORRECT statement from the multiple choices. CH3 CH2CH3 HCH3O HCH3 CH3 CH2CH3 HCH3O CH3H CH3 CH2CH3 H HCH3 OCH3 CH3 CH2CH3 H CH3H OCH3 1 2 3 4 __ A. 1 is the sole product of this reaction. __ B. 3 is the sole product of this reaction. __ C. 2 is the sole product of this reaction. __ D. 2 and 4 are both products of this reaction. __ E. 4 is the sole product of this reaction. Rationale: Chapter 8 Problem 49b 1 2. What two compounds could be used to produce the compound whose structure is shown below from a Diels-Alder reaction? CO2CH3 Pick the structures of the two compounds which can be used in this Diels-Alder reaction from the numbered choices below. CO2CH3 CH2 CH CO2CH3 CO2CH3 1 2 3 4 5 6 __ A. Compounds 5 and 6 can be used in this reaction. __ B. Compounds 1 and 2 can be used in this reaction. __ C. Compounds 4 and 6 can be used in this reaction. __ D. Compounds 3 and 5 can be used in this reaction. __ E. Compounds 3 and 4 can be used in this reaction. Rationale: Chapter 7 Problem 61b 3. Find the elimination product(s) of (2S,3R)-2-chloro-3-methylpentane + high concentration of CH3O- among the numbered structures below. Choose the CORRECT product of this reaction. CH3CH3 H CH2CH3 CH2CH3 H CH3 CH3CH3CH2 H CH2CH3 CH3CH3 H CH CH2 1 2 3 4 __ A. 1 and 3 are both products of this reaction. __ B. 4 is the product of this reaction. __ C. 2 is the product of this reaction. __ D. 1 is the product of this reaction. __ E. 3 is the product of this reaction. Rationale: Chapter 9 Problem 47b 2 8. Rank the ions whose structures are shown below in order of DECREASING nucleophilicity in methanol (strongest nucleophile listed first). CH3CO O CH3CH2S CH3CH2O - - - 1 2 3 __ A. 2 > 3 > 1 __ B. 1 > 3 > 2 __ C. 1 > 2 > 3 __ D. 3 > 2 > 1 __ E. 2 > 1 > 3 Rationale: Chaptr 8 Problem 39a 9. Shown below is a curved-arrow mechanism for converting structure 1 into structure 5 . Which structure has the curved arrow(s) associated with it drawn INCORRECTLY ? : .. OH2 : .. OH2 + H3O CH CH3 Br 1 CH CH3 + 2 Br -+ CH3 + 3 OH H CH3 + 4 + OH CH3 5 __ A. 3 __ B. 5 __ C. 4 __ D. 1 __ E. 2 Rationale: Chapter 8 Problem 58a 5 10. Two curved-arrow mechanisms are shown for the reaction of 4-bromocyclohexanol with HO- to form substitution products. Figure out the substitution mechanism(s) for the reaction of cis-4-bromocyclohexanol and trans-4-bromocyclohexanol with HO- to form product(s). Choose the CORRECT statement from the multitple choices. mechanism 1 mechanism 2 O BrH .. .. O Br: .. .. - O OH Br OH OH : .. .. - OH :.. ..- OH __ A. cis-4-bromocyclohexanol undergoes mechanism 2. __ B. Neither cis-4-bromocyclohexanol nor trans-4-bromocyclohexanol undergo mechanism 2. __ C. cis-4-bromocyclohexanol undergoes mechanism 1. __ D. trans-4-bromocyclohexanol cannot react by either mechanism. __ E. Both cis-4-bromocyclohexanol and trans-4-bromocyclohexanol undergo mechanism 1. Rationale: Chapter 9 Problem 54a 11. Use the numbered structures shown below to choose the CORRECT statement from the multiple choices. Cl Cl O Cl Cl Cl 1 2 3 4 5 __ A. (CH3) 3CBr will react faster with CH3CH2OH than it will with H2O. __ B. (CH3) 2CHS- will react faster with 1 than CH3S- will. __ C. 3 will not react with HO-. __ D. 5 will react with H2O faster than 4 will. __ E. 2 will react with HO- faster than 3 will. Rationale: Chapter 8 Problem 45 6 12. Which of the structures shown below has delocalized electrons? CH2 CH CH2CH CH2 CH2NH CH2CH CH2CH3 .. N H .. O.. .. CH2NH2 .. 1 2 3 4 5 __ A. structure 4 __ B. structure 3 __ C. structure 5 __ D. structure 2 __ E. structure 1 Rationale: Chapter 7 Problem 4 13. Name the dienes shown below and rank them in order of INCREASING stability (name of least stable diene listed first). CH2 CH CH2CH CH2 CH3CH CH CH CH2CH3CH CH CH CH CH3 CH3C CH CH C CH3 CH3 CH3 __ A. 1,5-pentanediene < 2,5-pentanediene < 2,5-hexanediene < 2,5-dimethyl-2,5-hexanediene __ B. 1,4-pentadiene < 1,3-pentadiene < 2,4-hexadiene < 2,5-dimethyl-2,4-hexadiene __ C. 1,3-pentadiene < 2,4-hexadiene < 1,4-pentadiene < 2,5-dimethyl-2,4-hexadiene __ D. 2,5-dimethyl-2,4-hexadiene < 2,4-hexadiene < 1,3-pentadiene < 1,4-pentadiene __ E. 2,5-dimethyl-2,5-hexanediene < 2,5-hexanediene < 2,5-pentanediene < 1,5-pentanediene Rationale: Chapter 7 Problem 10 7