Ochem Fall Test 2022, Exams of Organic Chemistry

Old test from Fall 2022 for Organic Chemistry

Typology: Exams

2021/2022

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CHEMISTRY 2211 SCALEUP, CHEM 2311H and CHEM 2411
EXAM 2
October 12, 2022
Be sure to read each question carefully. Partial credit may be assigned where warranted. Only answers
written in the boxes or on the lines will be graded. You must write your name and myID on pages 1,3,
5, 7 and 9 or two points will be deducted from your exam total for each omission. No student ID = -2
points.
1. (20 pts) Consider the following alkenes and answer the questions below by filling in the
appropriate bubbles corresponding to your choices under each question:
a. Which of these compounds can be accurately described as a cis isomer? Select all that apply.
b. Which of these compounds can be accurately described as a trans isomer? Select all that apply.
c. Which of these compounds can be accurately described as a Z isomer? Select all that apply.
d. Which of these compounds can be accurately described as an E isomer? Select all that apply.
There are 110 points available on this exam.
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CHEMISTRY 2211 SCALEUP, CHEM 2311H and CHEM 2411 EXAM 2 October 12, 2022 Be sure to read each question carefully. Partial credit may be assigned where warranted. Only answers written in the boxes or on the lines will be graded. You must write your name and myID on pages 1,3, 5, 7 and 9 or two points will be deducted from your exam total for each omission. No student ID = - 2 points.

  1. ( 20 pts) Consider the following alkenes and answer the questions below by filling in the appropriate bubbles corresponding to your choices under each question: a. Which of these compounds can be accurately described as a cis isomer? Select all that apply. b. Which of these compounds can be accurately described as a trans isomer? Select all that apply. c. Which of these compounds can be accurately described as a Z isomer? Select all that apply. d. Which of these compounds can be accurately described as an E isomer? Select all that apply. There are 1 10 points available on this exam.

e. Which of these compounds contain ONLY R chiral centers? Select all that apply. f. Which of these compounds contain ONLY S chiral centers? Select all that apply. g. Which of these compounds do not exhibit stereochemistry? Select all that apply.

  1. (8 points) Consider the four IR spectra shown below. Write the number of the compound (1-9) expected to produce that IR spectrum in its associated box. a.
  1. (21 points) a. (5 points) Shown below is the radical cation formed when a sample of 1-chloro-2,2- dimethylbutane is ionized in a mass spectrometer. Show the complete curved arrow mechanism for heterolytic (inductive) cleavage of the radical cation provided and then show the fragment(s) that result from said cleavage. b. (2 points) Shown below is the radical cation formed when a sample of 2-hexanol is ionized in a mass spectrometer. Provide the m/z value for the signal produced when the provided radical cation undergoes a dehydration. c. (7 points) Shown below is the radical cation formed when a sample of 2-methyl- 1 - propoxybutane is ionized in a mass spectrometer. Show the complete curved arrow mechanism for the most abundant homolytic (alpha) cleavage that can occur for the radical cation provided and show the fragment(s) that result from said cleavage. d. (7 points) Shown below is the radical cation formed when a sample of 4,4,5-trimethyl- 3 - hexanone is ionized in a mass spectrometer. Show the complete curved arrow mechanism for the McLafferty rearrangement for the radical cation provided and show the fragment(s) that result from said cleavage.
  1. (1 8 points) Assign R , S configurations to each of the chiral centers in the compounds below. The configuration must be unambiguously associated with the carbon to be considered for credit. If a compound is a meso compound, darken the bubble in the box.
  2. ( 9 points) Identify the relationship between each pair of structures as unrelated , identical , conformers , constitutional isomers , geometric diastereomers , enantiomers , or chiral diastereomers. a. b. c.
  1. (8 points) Identify the number of unique signals expected in the 1 H NMR spectrum for each of the compounds below (TEXTBOOK PROBLEMS). a. b. c. d.
  2. (8 points) Consider the two chair conformers of (1 R ,2 R ,4 R )- 1 - isopropyl-2,4-dimethylcyclohexane. Using the energy values in the chart at the end of the exam, calculate the energy value of each conformer to three significant figures. You must show your work in order to receive credit for the total energy values.
  3. (8 points) Draw the two chair conformers of trans - 1 - bromo- 4 - ethylcyclohexane in the appropriately labelled boxes.