TCHEM 261 Clark Atlanta University IR Spectroscopy Questions

Problem Set K1 – IR Spectroscopy
TCHEM 261 Winter 2023
Complete the following problems and submit as a hard copy. (You are welcome to
hand-write these. Blank copies available in class. See Canvas for due dates.
1. In Klein 2nd Semester Topics, read Ch. 2. Do Problems 2.2-2.4, 2.7, 2.9-2.14, 2.152.20, 2.22
Use an attached sheet for answers.
2. Could IR be used to distinguish the following compounds? If yes, explain how the
spectra would differ.
c.
and
d.
3. Explain how IR could be used to tell when each reaction is complete.
Problem Set (PS) J – Addition
Smith Chapters 10 & 11, Klein Chapters 11 & 12 (selected)
Due Feb. 1, 2022
Note: Optional problems generally offer more practice with the same concepts and
skills covered in the required problems. You know best whether you need the
additional practice. Also, it is expected that reading a section includes doing the
imbedded problems.
How to Grade and Submit Your Homework
After you complete the required pencil and paper homework problems, find a writing implement
of a different color than what you did your work with and self-grade all of the problems for
which an answer is provided on the answer key. A key will be provided before Monday
morning. Some problems, highlighted in red, will not have answers on the key. These may be
graded by the instructors for correctness.
*-Put a star by any question that was completely correct.
X- Put an X by any question that was partially or completely off. Write in the correct answer.
Briefly explain what caused you to write an incorrect answer. (Examples; missed part of
directions, mixed up substituent names, forgot to count all the hydrogen atoms, etc)
– Make a list of homework questions you would like to see worked or that you have questions
about.
– Add any concept/ content questions that you want clarified.
– Make a plan to see me or a TLC tutor or work with a study buddy to get these questions
answered.
– Turn in a hard copy or scan and upload the original work, any corrections and your questions as
a gradable part of your homework.
1
Part 1
Reading/
Watching
Topic
Smith 10.1-2
Smith 10.3-10.4
Degrees of Unsaturation
Alkene Nomenclature & Properties –
Review as needed
Smith 11.1-4
Smith 10.8-9,
Alkyne Review – From first quarter
Addition Rxns – Intro &
Hydrohalogenation
Regiochemistry of Addition –
Markovikov’s Rule
Stereochemistry Considerations in
Addition Reactions
Hydration
Smith 10.10
Klein 11.1-4
Smith 10.11
Smith 10.12
Klein 11.6
Smith 10.13-15
Klein 11.9
Problems
Halogenation & Halohydrin
Formation
From Smith unless
specified
10.35a,c,d,f; 36
10.46
10.53; 10.54, 10.55
Klein 11.2-3
Klein 11.7-10,
Optional
Problems
10.35, 36
37(E/Z review)
38(review),
39(review)
11.26, 11.27
10.47
Klein 11.12-15,
Klein 11.59-62
Klein 11.100-103;
Reading/
Watching
Topic
Problems
Klein 11.3
Smith 10.16
Klein 11.7
Hydrogenation
Hydroboration
Klein 11.27-32
Klein 11.64-69
Smith 11.6-10
Addition Rxns – Mixed Practice
Alkyne Reactions
10.57- 59,
11.29, 30, 33,
Klein 11.8
Applications
Synthesis
10.45
Smith 10.63a-f
From Smith unless specified
2
Optional
Problems
10.49, 52, 60-63
11.36, 38, 51
11.22-23, 11.34,
36
Klein 11.71-78;
11.81, 83, 87, 88;
Problems and Answers
Part 1
10.35 Calculate the number of degrees of unsaturation for each molecular formula.
a. C6H8
c. C10H16O2
d. C8H9Br
f. C7H11N
10.36 How many rings and π bonds does a compound with molecular formula C10H14 possess?
List all possibilities.
3
11.26 Answer the following questions about erlotinib and terbinafine. Erlotinib, sold under the
trade name Tarceva, was introduced in 2004 for the treatment of lung cancer. Terbinafine is an
antifungal medication used to treat ringworm and fungal nail infections.
a. Which C−H bond in erlotinib is most acidic?
b. What orbitals are used to form the shortest C−C single bond in erlotinib?
c. Rank the labeled bonds in terbinafine in order of increasing bond strength.
d. Draw two additional resonance structures for terbinafine that contain all uncharged atoms.
11.27 Give the IUPAC name for each alkyne.
c.
f.
4
Gradable: 10.53 Which alkene reacts faster with HBr? Explain your choice.
Gradable: 10.55 Draw a stepwise mechanism for the following reaction.
5
Part 2 – PS J (Addition)
10.46 Draw the products formed when (CH3)2C=CH2 is treated with each reagent.
b. H2O, H2SO4
c. CH3CH2OH, H2SO4
d. Cl2
e. Br2, H2O
f. NBS (aqueous DMSO)
g. [1] BH3; [2] H2O2, HO−
6
10.47 What alkene can be used to prepare each alkyl halide or dihalide as the exclusive or major
product of an addition reaction?
a.
b.
c.
d.
10.49 Draw the constitutional isomer formed in each reaction.
a.
b.
7
c.
d.
e. (one to look up in the text)
f.
Gradable: 10.57 Draw a stepwise mechanism for the conversion of hex-5-en-1-ol to the cyclic
ether A.
8
Gradable 10.58 Draw a stepwise mechanism that shows how all three alcohols are formed from
the bicyclic alkene.
Gradeable: 10.59 Less stable alkenes can be isomerized to more stable alkenes by treatment with
strong acid. For example, 2,3-dimethylbut-1-ene is converted to 2,3-dimethylbut-2-ene when
treated with H2SO4. Draw a stepwise mechanism for this isomerization process.
Optional: 10.60 When buta-1,3-diene (CH2═CH−CH═CH2) is treated with HBr, two
constitutional isomers are formed, CH3CHBrCH═CH2 and BrCH2CH═CHCH3. Draw a
stepwise mechanism that accounts for the formation of both products.
9
11.28 Give the structure corresponding to each name.
a. 5,6-dimethylhept-2-yne
b. 5-tert-butyl-6,6-dimethylnon-3-yne
c. (S)-4-chloropent-2-yne
d. cis-1-ethynyl-2-methylcyclopentane
e. 3,4-dimethylocta-1,5-diyne
f. (Z)-6-methyloct-6-en-1-yne
11.29 Label each pair of compounds as keto–enol tautomers or constitutional isomers, but not
tautomers.
a.
b.
10
c.
d.
30. Draw the enol form of each keto tautomer in parts (a) and (b), and the keto form of each enol
tautomer in parts (c) and (d).
a.
b.
11
c.
d.
11.33. Draw the products formed when hex-1-yne is treated with each reagent.
a. HCl (2 equiv)
b. HBr (2 equiv)
c. Cl2 (2 equiv)
d. H2O+H2SO4+HgSO4
e. [1] R2BH; [2] H2O2, HO−
f. NaH
g. [1] −NH2; [2] CH3CH2Br
h.
12
11.34 What reagents are needed to convert (CH3CH2)3CC≡CH to each compound?
a)
b)
c)
d)
13
11.36 What alkynes give each of the following ketones as the only product after hydration with
H2O, H2SO4, and HgSO4?
a)
b)
c)
11.22 Use retrosynthetic analysis to show how hex-3-yne can be prepared from acetylene and
any other organic and inorganic compounds. Then draw the synthesis in the synthetic direction,
showing all needed reagents.
14
11.23 Devise a synthesis of CH3CH2CH2CHO from two-carbon starting materials.
15
Problem Set (PS) K2 – H-NMR Spectroscopy
Smith Section C, Klein 2: Chapter 3
Due Feb. 1, 2022
Note: Optional problems generally offer more practice with the same concepts and
skills covered in the required problems. You know best whether you need the
additional practice. Also, it is expected that reading a section includes doing the
imbedded problems.
How to Grade and Submit Your Homework
The Klein problems have answers at the back of the book. Please grade your own work in a
different color, and re-do any you missed. Klein problems will be graded for completion.
Problems from Klein 2nd Semester
Topic
Required
Chemical Equivalence
3.2, 3.3, 3.9
Chemical Shift
3.13, 3.15, 3.17, 3.19
Integration
3.21, 3.22
Multiplicity/ Splitting 3.25, 3.30
Pattern Recognition
3.32, 3.34
Hydrogen Deficiency
3.36, 3.37
(Degrees of Unsat.)
Analyzing Spectra
3.43, 3.44
Optional
3.4-3.10
3.14, 16,18
3.23
3.26-29
3.31, 3.33
3.38-3.41
3.45-48
Other Problems – Gradable
1. What effect will changing from an operating frequency of 60 MHz to an operating frequency
of 100 MHz on each of the following values? Will they increase, decrease, or stay the same?
a. the frequency of absorption in Hz?
b. the chemical shift in ppm?
c. the magnitude of a coupling constant, J, in Hz?
2. Label the signals due to Ha, Hb, and Hc in the H-NMR Spectrum of acetonitrile. Draw a
splitting diagram for the splitting due to the Ha proton.
3. From the spectra given, please determine the structure of the compound. It has the formula
C8H10O and 6 unique carbons.
IR Spectrum of C8H10O
H-NMR Spectrum of C8H10O
H-NMR Table
Signal #
1
2
3
4
Chemical Shift, ppm
2.35
2.86
3.8
7.2-7.4
Splitting
Singlet (s)
Triplet (t)
Triplet (t)
Doublet of
triplets
Relative Area
2
4
4
10
4. From the spectra given, please determine the structure of the compound. It has the formula
C7H8O2 and seven unique carbons.
IR Spectrum of C7H8O2
overtones
H-NMR Spectrum of C7H8O2
Areas:
7.2-6.4 ppm =12,
5.6 ppm = 3,
3.8 ppm = 9
Splitting
complicated,
singlet
singlet
5. Match the H-NMR spectra described in the tables below to the correct compound (A, B, C, or
D). Add and label the matching protons.
Spectrum 1
δ splitting integration Proton
3.69
s
3
2.63
s
2
Answers:
Compound A produces Spectrum ________
Spectrum 2
δ splitting integration Proton
3.68
s
3
2.99
t
2
1.95 quintet
1
Compound B produces Spectrum ________
Spectrum 3
δ splitting integration
4.11
q
4
2.61
s
4
1.35
t
6
Compound D produces Spectrum ________
Spectrum 4
δ splitting integration
4.14
q
2
2.62
s
1
1.26
t
3
Proton
Proton
Compound C produces Spectrum ________