CHML212
Exp. 20 Reduction of p-Vanillin
IN-LAB ASSIGNMENT: (EACH STUDENT will record the following data in his/her laboratory notebook in a well organized
manner during lab period. Yellow carbon copies will be submitted for grading along with Post-Lab assignment.) …..max
score = 20 pts.
6. Data/Calculations
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
Initial mass of p-vanillin used
Volume of NaBH4 solution used
Volumes of ethanol and 6M HCl used
Weights of small filter paper, filter + product, and final product mass
HPLC vial slot #
TLC diagram, including all cm measurements
Example Rf calculation
Theoretical yield calculation
% yield calculation
Atom economy calculation
Experimental atom economy calculation
“Eproduct” calculation
Cost per synthesis calculation
Cost per gram calculation
7. In-lab Question (The following question should be answered in laboratory notebook.)
a.
Draw the product, and a complete mechanism for its formation, for the following reaction. In your
mechanism, use only the hydride ion as your nucleophile.
O
1. NaBH4
2. H3O+ workup
?
CHML212
Exp. 20 Reduction of p-Vanillin
POST-LAB ASSIGNMENT: (EACH LAB GROUP will submit one copy of a typewritten, paragraph style report addressing
all of the points listed below. Must be written using PAST TENSE, PASSIVE VOICE. ) …..max score = 50 pts.
8. Experimental (Write 1-2 paragraphs including all of the following. Do NOT present a bulleted outline.)




What type of reaction did you perform?
Describe the actual synthetic procedure. Include names of any reactants used and desired product, as well as
name of solvent and catalyst used (if any). Be sure to give actual volumes/masses of compounds used during the
synthesis (not just what the lab manual tells you to use).
Describe the purification technique used to isolate the desired product, including names and actual volume/mass
of any compounds used during the purification process.
Describe the analytical technique used to evaluate the product, including names and actual volumes of any
compounds used during sample preparation, and any type of spectral analysis used.
9. Results (Completed tables. Sketch diagram of TLC plate, including all spots. Once complete, copy/paste tables into your document.)
Table 20.1 TLC Analysis
Compound
Standard
Rf
Sample
Rf
TLC Diagram
Solvent Front = ________ cm
p-vanillin
Vanillyl
Alcohol
Table 20.2 IR Analysis
OH stretch
Base
Values
Frequency
(cm-1)
3200-3600
C-O stretch
C=O stretch
1000-1300
1680-1740
Functional Group
p-vanillin
Vanillyl alcohol
Frequency
(cm-1)
Frequency
(cm-1)
Table 20.3 1H NMR Analysis
p-vanillin
O
vanillyl alcohol
H1
C
HO
7
CH2
1
6
2
6
2
5
5
OCH3
OCH3
3
3
OH
OH
4
H#
1
2,6
3
4 (OH)
5
4

(ppm)
Int.
Mult.
7.42
2
m
H#
1
2
3
4 (OH)
5,6
7 (OH)

(ppm)
Int.
Mult.
6.71
2
m
Table 20.4 Experimental Results
Table 20.5 Green Chemistry Results
Atom Economy (%)
Experimental Atom
Economy (%)
“Eproduct”
Cost per synthesis ($)
Cost per gram ($/g)
Theoretical yield (g)
Actual yield (g)
Percent yield
Product Appearance
Experimental Melting Point (oC)
Compound
Table 20.6 HPLC Analysis
HPLC Retention Times
(min)
Standard
Sample
p-vanillin
Vanillyl alcohol
10. Discussion (Write 1-2 paragraphs including the following.)





Based on TLC and HPLC analyses, was the p-vanillin completely reduced to vanillyl alcohol? Identify any
compounds present in the sample. Give HPLC retention times, area percent values, and TLC R f values for any
compounds present in the sample.
How can IR spectroscopy be used to differentiate between the reactant and the product in this experiment? Give
the identity of one type of absorption and explain how it could be used to determine whether or not the
conversion took place. Include the typical frequency and the actual frequency for this type of bond in your
statement.
How can NMR spectroscopy be used to differentiate between the reactant and the product in this experiment?
Give the identity of one type of proton and how it could be used to determine whether or not the conversion took
place. Include the typical chemical shift and the actual chemical shift for this type of proton in your statement.
Include a short comment addressing what could be done differently to improve the experimental results, if
repeated.
Be sure to attach HPLC chromatogram!