OChem 1 Practice Final Exam SU21 PDF

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Practice Final Exam...

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Organic Chemistry I Practice Final Exam 9 July 2021 Name: _________________________________ Section TA: _________________________ Directions. You have 3 hours from the indicated start time to complete this exam and upload it to Gradescope, unless otherwise noted. This exam is closed book and closed notes. Any violation of the academic ethics policy will result in disciplinary action. To receive credit for this exam, the honor pledge on this page must be signed and dated. There are 8 problems on this exam for a total of 100 points. Your scanned PDF should include 8 pages. Your PDF should be formatted as follows: Page 1: Name, Section TA, Honor Pledge Page 2: Problem 1 (a-c), Problem 2 (a-c) Page 3: Problem 3 (a-d) Page 4: Problem 4 (a-c) Page 5: Problem 5 Page 6: Problem 6 (a-c) Page 7: Problem 7 (a-c) Page 8: Problem 8

Honor Pledge I certify that I have completed this exam without unauthorized assistance from any materials, person, or device. Sign and date here: ____________________________

Late or incorrectly formatted submissions are subject to a 5-point deduction. Good luck!

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1. [6 points] The compound below is treated with excess HCl. How many equivalents need to be added to cause a carbocation rearrangement to occur? What type of rearrangement occurs? Me Me

2. [8 points] Propose a synthesis for the target below from the indicated starting material. You may use any inorganic or monofunctional organic reagents you choose, including dienes and dienophiles, as long as they add no more than 6 carbons in a single step. Me

Me

several steps Me

Me

2

3. Consider the reaction below. Me

Me Me MeOH Br

several regioisomers

(a) [10 points] Draw all isomers, including stereoisomers, that are possible when the reaction above occurs under mild conditions.

(b) [4 points] Which regioisomer forms in greatest yield? Why?

(c) [2 points] Which reaction mechanism becomes more favorable if the reaction above is heated to 100 ℃?

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4. Consider the compound below. CH3 N (H3C)2N

N

C (a) [4 points] How many atoms in the structure above have an orthogonal set of unhybridized p-orbitals?

(b) [4 points] Analysis of the compound above using x-ray crystallography shows that one of its nitrogen atoms exhibits tetrahedral geometry. Which one is it and why?

(c) [4 points] Label the two most acidic positions in the compound above and explain WHY those positions are relatively acidic.

(d) [4 points] CLEARLY circle the lone pair(s) that sit in unhybridized p-orbitals and explain WHY they sit in unhybridized p-orbitals.

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5. The statements below are TRUE. Explain WHY they are true. (a) [4 points] The hydroboration-oxidation product of the compound below is aromatic, assuming only one equivalent of BH3 is used.

(b) [4 points] It is impossible for a compound with a molecular formula of C11H16O to contain three double bonds and two rings.

(c) [4 points] In some cases, KOtBu can participate in a substitution reaction, even when solvated in tBuOH and heated.

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6. [24 points] Provide the missing starting compound(s) AND reagents for each of the reactions below, given the product and molecular formula of the starting material.

O

O

H

H

C5H4

O O C18H24O2

CN Me

Me

C5H11I

Me Me C7H13Cl

NC

CN

C4H6

O H H C4H6 + C4H4O

O

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7. [6 points] Draw the most stable stereoisomer product for the compound below. Use the space below to show your work and use chair conformations to explain WHY the stereoisomer you drew is the most stable.

Me Me

1. 9BBN-THF 2. H2O2, NaOH

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8. [12 points] Propose a synthesis for the target below from the indicated starting material. You may use any inorganic or monofunctional organic reagents you choose, including dienes and dienophiles, as long as they add no more than 6 carbons in a single step. It is possible that other stereoisomers may have formed within this synthesis. O O

OH

O

Me Me

Me

Me O

several steps

O O

End of the 100-point portion. 8

9. [10 points] Rank the compounds below in order of DECREASING activation towards electrophilic aromatic substitution reactions. Explain your reasoning. O O

N

O

NH2

A

HN

B

Me

C

O

Me

D

Me

E

10. [8 points] The transformation below is possible in just four steps. Propose the four steps necessary to synthesize the target below from the indicated starting material. Br

O

1. 2.

Me

3. 4.

SO3H O

Cl

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11. [12 points] Propose a synthesis for the target below from the indicated starting material. You may use any inorganic or monofunctional organic reagents you choose, including dienes and dienophiles, as long as they add no more than 6 carbons in a single step. O

Me

O

Me

several steps

12. [8 points] Draw the product observed after the compound below is treated with excess NaOMe. NO2 F

F

F

F F

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13. [12 points] Provide the reagents necessary to carry out the following syntheses. Up to 5 steps may go in one box.

Br

Br

O O

Me

Me

Cl Et

End of the exam. Have a great summer! 11

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From P. Scudder, Electron Flow in Organic Chemistry, 2nd ed.

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