Boston College
CH23101, Organic Chemistry I
Professor Kelly
Exam #3: December 7, 2012
Name: __________________________
(print, legibly please)
Directions: There are 9 numbered pages not including this page (Note: several of these pages
have considerable blank space on them). Be sure that NONE of the pages is missing. Scratch
paper is attached and may be removed.
Write answers in the spaces provided.
Do not dawdle; budget your time wisely!
1. (12pts) Consider the molecule below (assume rapid rotation around single bonds):
What will be approximately the chemical shift (ppm = δ) for hydrogens A?__________
For hydrogens B? __________
Which hydrogen(s) will give rise to a resonance furthest downfield ( = furthest to the left)?
__________
Which, if any, of the six designated resonances (A-F) will appear as a singlet [if so give its/their
letter(s), otherwise say "none"]? __________
As a triplet? __________
As a quartet? __________
As more peaks than a quartet? If yes, how many peaks? __________
Will any set of resonances (be it a singlet, doublet, triplet, or anything else) integrate for more
than 3 hydrogens? If no, say "no." If yes, give the letter(s) for the hydrogens whose resonances
will integrate to ≥4 hydrogens. __________
2. (4pts)
(a) Give on the line the name of:
______________________________________________________________________________
(b) Give the complete name for:
____________________________________________________________________________
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3. (6pts)
(a) Put in the box the structure of a 4-carbon Grignard reagent that would give alcohol A
after a standard Grignard reaction.
(b) Give in the box the structure of a 5-carbon ketone that would give X after reaction with
an appropriate Grignard reagent.
4. (4pts) Reaction of a 6-carbon secondary alcohol A gave the tertiary chloride B. Apparently,
a rearrangement occurred. Give in the box a reasonable structure for A.
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5. (4pts) Give in the box the letter of the one compound below that gives rise to the spectrum
shown:
6. (3pts) The reaction below gives a mixture of two alkenes, one of which contains deuterium
(D). Using a line drawing put in the box, including stereochemistry, the structure of the Dcontaining alkene.
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7. (6pts) Indicate in the boxes how many resonances appear in the 13C (carbon!) NMR (with 1H
decoupling) spectrum of the following compounds.
8. (4pts) We have not discussed the combustion of alkenes in class, but you should be able to
figure out the answer to this question anyway.
The combustion of ethene is shown by the equation below:
For the four alkenes shown below, which will have the most negative ΔHcombustion (-20 is more
negative than -10)? __________
The least negative ΔHcombustion? __________
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9. (12pts) Provide in the boxes the missing starting material, reagent(s), or organic product. Do
4, omit one, and indicate which.
*If the starting material or product shown is chiral, use wedge/dashed notation to indicate the
configuration of the corresponding product or starting material. If a racemic mixture is
expected, say that.
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10. (3pts) The reaction sequence below was suggested by the assigned Chemical Highlight 9-2.
Chloroalcohol Z was subjected to the following sequence of reactions. Give the structure of
the product P.
11. (6pts) Ignoring splitting, how many resonances would there be in the 1H (proton!) spectra of
the two compounds shown? Put answers in the boxes.
12. (6pts) Reaction of dichloroether D with Na2S ( = 2Na+ and S2-) gave a mixture of A and B,
both of which contain sulfur. The entire 1H NMR spectrum of A is just one singlet; the entire
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H NMR spectrum of B is also just one singlet (not exactly the same chemical shift as in A),
but B is twice the molecular weight of A. In the boxes, give the structures of A and B.
A
B
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13. (6pts) Reaction of a Grignard reagent with an oxacyclopropane (also known as an epoxide)
gave W upon work-up. In the boxes, place reasonable structures for the Grignard reagent
and the oxacyclopropane.
14. (6pts) (a) Indicate on the line how many degrees of unsaturation a molecule with the
formula C7H10O has. __________
(b) A compound with the formula C6H7BrS has one double bond. How many rings does it
have (circle correct answer)?
0
1
2
3
4
-1
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15. (4pts) An ester has the formula C4H7ClO2 and gives the 1H NMR spectrum below. Give its
structure in the box.
Note: The following problem may be time consuming. Think twice about whether working
on it is the best investment of your time.
16. (4pts) Give in the box a reasonable structure for a compound that has the following
properties:
 Contains 5 carbons
 The proton-decoupled 13C NMR spectrum contains four peaks
 Contains one bromine
 Has 2 degrees of unsaturation
There may be more than one correct answer (and certainly many incorrect ones).
Note: One more page to go!
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17. (10pts) Synthesize two (indicate which one you want to omit) of the compounds below from
the starting materials specified and any inorganic reagents you wish. Do not give
mechanisms. Each of the syntheses will require two or more steps. A sample question and
answer are provided. Write the structure of the product after each step.
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