Follow-up to experiments #3a and #3b
For Experiment #3a:
1. (1 point) The purpose of today’s experiment.
2. (2 points) Your hypothesis of which product(s) should preferentially form
according to the mechanism of the reaction and which should not (you’ll have to show
the complete mechanism of reaction). You can refer to pages 542-553 and pages 560-562.
3. (2 points) The outcome of a molecular modeling experiment that show the most
likely site for electrophilic substitution on your aromatic system (that is, use PC
Spartan to build, minimize, and evaluate the electrophilicity of various ring carbons).
You’ll want to use previous examples from last semester as a model or maybe
Experiments 5 and 6 from you "Molecular Modeling Workbook for Organic
Chemistry". This information should be consistent with the hypothesis you put forth
in part 1b.
4. (2 points) Summarize the results of your NMR analysis being sure to include
the original spectrum with the structure(s) drawn on it and with all protons
properly labeled. You will want to consider the coupling constants (J
values) for ortho, meta, and para coupling for a more complete analysis (Jortho
= 6-10 Hz, Jmeta = 1-3 Hz, and Jpara = 0-1 Hz).
5. (2 points) Explain, in detail, whether the results of this experiment (NMR)
support or refute your hypothesis. Is your NMR data consistent with the predictions from
the known mechanism of the reaction and the results of your molecular modeling experiment?
If the results are contradictory, provide a reason why these results occurred.
For Experiment #3b:
You will be expected to produce a "results" section and a "discussion"
section for this experiment as follows:
Results section:
1. (1 point) The mass of products and the calculation of the percent yield for the
reaction(s) that YOUR GROUP performed.
2. (1 point) The melting points for the products that YOUR GROUP
isolated. Include the reference melting points for these compounds as found in the
literature (e.g. the Aldrich catalog).
3. (3 points) Submit the following copies of your 3 proton NMR spectra:
- the full spectrum from 0-10 ppm with integrals
- a fully-labeled (protons) ChemDraw representation of the molecule
- any close-up views (zoomed) that are useful in elucidating the structure of your
products
4. (3 points) Submit the following information in a table of NMR data for each of
your 3 proton NMR spectra:
- chemical shifts
- integrals
- splitting patterns
- coupling constants (J values)
- peak assignments (the letter or number should correspond to the same letter or number on
the aforementioned ChemDraw representation of the molecule)
5. (1 point) A summary of relevant Mass Spectral data (MI peak, base peak,
assignment of major fragments, MW) for both the initial product and final product in the
experiments performed by Teams 2-5.
Discussion section:
1. (3 points) The hypothesis of your experiment (e.g. what products do you expect to
form in each reaction of the three reaction performed in this experiment) including a
DETAILED analysis of the mechanisms of reaction. Your analysis should include a
description of activating/deactivating effects in addition to directing effects. You
should include a description of how polar and resonance effects of the substituents on
your ring(s) contribute to ring activation or deactivation. Refer to section 11.4 of Fox
and Whitesell.
2. (2 points) A summary of the MAJOR pieces of data that enabled you to elucidate
the structures of your reaction products. Discuss whether or not these structures are
consistent with those you proposed in your hypothesis.
3. (2 points) FOR THE REACTIONS PERFORMED BY TEAMS 2-5: Compare/contrast the
results between the two different reaction sequences. Did you get the same or different
products? Discuss the significant similarities and/or differences of the results/data.
Provide an explanation as to why these similarities and/or differences exist. You will
want to focus this part of your discussion on the events occurring during the course of
the reaction mechanism.
Follow-up to experiment #4
For this experiment, you will write up a critical discussion of your
results which should include the following information:
(a) 10 points: a complete summary of the IR data and NMR data for your starting
material and describe how you used the data (critical analysis of the data) to
arrive at its structure.
(b) 10 points: a complete summary of the melting point/boiling point, IR data, and NMR
data for your purified product and describe how you used the data
(critical analysis of the data) to arrive at its structure.
(c) 5 points: provide a mechanism to show how your starting material was converted into
the product --- also, indicate the type of rearrangement reaction that occurred.
NOTE: Your IR and NMR data should be compiled into tables along with
accompanying labeled structures of your starting material and
product. If you do not understand what I mean by this, then you need to see me!
Follow-up to experiments #5a and #5b
For Experiment #5a
1. (1 point) Report the mass and percent yield for BOTH the Grignard and Wittig
reactions. Be sure to show all of your work for the calculation of the percent
yield. Did you achieve a reasonable yield? Explain.
2. (3 points) Compile all of the data you collected for melting point and NMR for
the Grignard reaction in the following fashion:
(a) Report the actual melting point for your product of the Grignard
reaction along with the literature melting point (including references).
(b) Include a hard copy of your proton NMR with integrals and peak picking. Also,
draw a labeled structure directly on the spectrum. Provide any close-up (zoomed)
views that are helpful in seeing the splitting patterns.
(c) Include a hard copy of your carbon NMR with a labeled structure drawn directly on the
spectrum.
3. (2 points) What does the data indicate? Did you achieve the
desired product? Explain by interpreting your experimental
data from question #2. Be sure to also include any critical observations you made
during the course of the reaction.
4. (1 point) How did this product form (what's the mechanism)?
5. (1 point) During the experimental work-up, you employed a 10% NaOH solution to
isolate the product, followed by acidification with conc. HCl. Describe (in detail)
the chemistry that's occurring during this phase of the experiment as it pertains to your
product. You'll likely want to employ drawings and structures to illustrate the
critical features of the chemistry.
6. (3 points) Compile all of the data you collected for melting point and NMR for
the Wittig reaction in the following fashion:
(a) Report the actual melting point for your product of the Wittig
reaction along with the literature melting point (including references).
(b) Include a hard copy of your proton NMR with integrals and peak picking. Also,
draw a labeled structure directly on the spectrum. Provide any close-up (zoomed)
views that are helpful in seeing the splitting patterns.
(c) Include a hard copy of your carbon NMR with a labeled structure drawn directly on the
spectrum.
7. (2 points) What does the data indicate? Did you achieve the
desired product? Explain by interpreting your experimental
data from question #6. Be sure to also include any critical observations you made
during the course of the reaction.
8. (1 point) How did this product form (what's the mechanism)?
9. (1 point) Why did we use the 10 N solution of NaOH in this reaction? Be
sure to show the critical reaction occurring here.
Experiment #5b
1. (1 point) Report the identification number for your unknown alcohol.
2. (1 point) Report the mass and percent yield for the recovered crude ester
product. Did you achieve a reasonable yield of product? Evaluate any deviations from
an ideal yield.
3. (3 points) Compile all of the NMR data for the product ester including:
(a) a hard copy of the 13C NMR spectrum with peak
identification
(b) a hard copy of the proton NMR spectrum with integrals and peak picking. Also,
draw a labeled structure directly on the spectrum. Provide any close-up (zoomed)
views that are helpful in seeing the splitting patterns.
(c) a hard copy of 2D COSY spectrum with important cross peaks labeled.
4. (2 points) What does the data indicate? What is the
structure of your isolated ester product? Explain by interpreting
your experimental data from question #2. Pay particularly close attention here to
the coupling relationships identified from your 2D COSY spectrum.
Be sure to also include any critical observations you made during the course of the
reaction.
5. (1 point) From what starting alcohol and carboxylic acid did your product arise?
Work through (and show) the mechanism of the reaction to verify the ester's
production.
6. (1 point) Does your product contain any stereocenters? If so, identify
their location(s) within the structure of your ester product. Suggest how the
presence of stereogenic centers might affect the appearance of proton resonances in your
NMR spectrum.
7. (1 point) What's the purpose of using the Dowex 50 x 2-100 ion exchange resin in
this experiment?
Follow-up to experiment #6
1. (1 point) What is the purpose of today's experiment?
2. (1 point) What are the mass and percent yield of the product you isolated after
recrystallization?
3. (1 point) What is the melting point for your recrystallized product? What
does it indicate to you about the relative purity of your product? Is this purity
estimate consistent with your 1H-NMR (e.g. do you have a single product)?
4. (2 points) Attach copies of your proton NMR data. Draw a labeled structure
of your elucidated product directly on the spectra and indicate which peaks correspond to
each labeled hydrogen.
5. (2 points) Summarize (via a table) all relevant integrals and splitting patterns
for each labeled peak region. 6. (2 points) Note important (or telling)
coupling relationships and report their coupling constants. What type of coupling do
you think is occurring in each case? Do the coupling constant values make sense?
Explain.
7. (2 points) How might a 1H-1H COSY experiment be useful in
confirming your structure? Provide a sketch of what you think the spectrum might
look like.
8. (2 points) Attach copies of your carbon NMR data. Draw a labeled structure
of your elucidated product directly on the spectra and indicate which peaks correspond to
each labeled carbon. Are there any that are inconclusive? Explain.
9. (4 points) Explain via a narrative how your NMR (proton and carbon) enabled you
to determine the structure of your product.
10. (2 points) From which two starting materials did you start? Identify the
structure and name of the unknown aldehyde and unknown ketone components.
11. (2 points) Provide a complete step-wise reaction mechanism to illustrate how the
two ccarbonyl containing components gave rise to your elucidated product.
12. (2 points) Compare/contrast your experimental outcomes (and product identity)
with your partner team as indicated below:
Jessica and Jennifer with Ed, Kim, and Kimberly -- Both groups had
unknown aldehyde A (mol. formula = C5H4O2) with unknown
ketone A (mol. formula = C5H8O)
Terry and Jeff with Alicia, Stephanie, Julie, and Melissa -- Terry and Jeff had
unknown aldehyde B (mol. formula = C7H6O) with unknown ketone B
(mol. formula = C3H6O); Alicia and Stephanie had unknown aldehyde B
(mol. formula = C7H6O) with unknown ketone C (mol. formula = C6H10O);
Julie and Melissa's experiment failed, so simply use the results of one of the other two
groups here
13. (2 points) How might your final product react with a hard
nucleophile (strong base) (like a Grignard reagent or LiAlH4) versus a soft
nucleophile (weak base) (like a lithium dialkyl cuprate, an amine, or a b-dicarbonyl anion)? Show each reaction
and the expected products? Why do you get two different modes of addition (1,2
versus 1,4 addition)?
