-Developed an undergraduate inorganic chemistry laboratory experiment to showcase the catalytic coupling reaction between waste carbon dioxide and epoxides to yield value-added cyclic carbonate materials -Currently focused on maximizing the reaction yield and reducing experiment costs by employing bimetallic salen complexes in the catalytic system -Aided in the optimization of system conditions of coupling reaction in simple polypropylene centrifuge tubes and synthesis of bimetallic aluminum salen catalyst -Presented attached poster named "Undergraduate Inorganic Laboratory Development: Epoxides & CO2 Coupling Under Mild Conditions with Bimetallic [(salen)Al]2O" at the 259th American Chemical Society (ACS) National Meeting & Exposition through SciMeetings

1. Material Cost ($)
Two Centrifuge Tubes 1.30
2 mL epichlorohydrin 0.14
0.5% [(salen)Al]2O 2.70
2% nBu4NBr 0.07
TOTAL $4.41
Figure 2. Comparison of catalytic performance of 1 mol% (salen)AlCl & 2 mol% nBu4NBr system with
bimetallic [(salen)Al]2O and different loadings of cocatalyst nBu4NBr. Conversion analyzed via 1H NMR
for the coupling of epichlorohydrin and CO2 in a 50°C water bath for 10 minutes.
▪ Known and effective
catalyst system for
epoxide/CO2 coupling[6]
▪ Schlenk line synthesis
▪ Could be implemented as
an Inorganic Chemistry
laboratory experiment
Undergraduate Inorganic Laboratory Development: Epoxides & CO2
Coupling Under Mild Conditions with Bimetallic [(salen)Al]2O
Logan Fenimore and Dr. Stephanie Poland
Department of Chemistry and Biochemistry, Rose-Hulman Institute of Technology, Terre Haute, IN 47803
The Poland Group has been recently working to modify popular liquid CO2 extraction
experiments created for undergraduate laboratories to exhibit the catalytic coupling reaction
between CO2 and epoxides under mild conditions. This reaction has been optimized
recently to yield 9.5 ± 1.1% conversion to epichlorohydrin carbonate in just 10 minutes
utilizing 1 mol% (salen)AlCl and 2 mol% nBu4NBr from epichlorohydrin and dry ice.
However, this experiment costs over $6 per pair of students, which is likely prohibitive to
smaller laboratories. Herein, we have explored the use of the bimetallic complex
[(salen)Al]2O catalyst for this same process, yielding higher conversions to cyclic carbonate
products as compared to monometallic (salen)AlCl. Experimental costs are also reduced to
less than $4 per undergraduate laboratory despite the added synthetic step when compared
to (salen)AlCl/nBu4NBr systems. Chemical conversions can be confirmed by students using
1H NMR spectroscopy. Additionally, the [(salen)Al]2O catalyst calls for an air-free synthesis
fit for undergraduate Inorganic Chemistry laboratories, allowing for the implementation of a
multiweek experiment designed for students eager to learn challenging synthetic,
purification, and characterization techniques.
Abstract
Acknowledgements
▪ RHIT Department of Chemistry and Biochemistry
▪ Mr. Lou Johnson, Mrs. Cyndi Erwin, and Ms. Michelle Sharp
▪ Group Members: Zhen “Carmen” Ni, J. Blake McLemore, Ashley Braaksma,
Connor Ray, and Elliott Tong
References
Future Studies
[1] Poland, S.J.; Darenbourg, D.J. Green Chem. 2017, 19, 4990-5011.
[2] Pre-owned stainless steel Parr reactors were found on Ebay for ~$700-$1000 each.
www.ebay.com (accessed May 2018) Prices for newer reactors can be much higher.
[3] Prices from MilliporeSigma and VWR. (updated March 2019)
[4] McKenzie, L. C.; Thompson, J. E.; Sullivan, R.; Hutchison, J. E. Green Chem. 2004, 6, 355-358.
[5] Kalani, M.; Yunus, R. Int. J. Nanomed. 2011, 6, 1429-1442.
[6] North, M.; Young, C. Chem. Sus. Chem. 2011, 4, 1685-1693.
[7] Moore, D. R.; Cheng, M.; Lobkovsky, E. B.; Coates, G. W. J. Am. Chem. Soc. 2003, 125, 11911-
11924.
Exploring Alternate Catalyst Option:
Bimetallic [(salen)Al]2O
[(salen)Al]2O
Typical System
$700+ (used) [2]
Using high-purity
CO2 gas
Coupling Reaction of Epoxides and CO2
[1]
Epoxide Polycarbonate Cyclic Carbonate
$0.65 / tube [3]
Our System
Using dry ice
• 15 mL polypropylene
centrifuge tube
• Freshly prepared dry ice
powder
• Copper wire coil separator
• Mixture of epoxide,
catalyst and cocatalyst
Undergraduate Laboratory Experiment Design
1. Add epoxide, catalyst, and cocatalyst in an
i : j : 100 molar ratio to the centrifuge tube.
2. Place a copper wire into the tube.
3. Fill tube with finely powdered dry ice and
cap tightly.
4. Place tube into a plastic cylinder that is filled
with 50 °C warm water.
5. Run the coupling reaction for 10 minutes.
6. Analyze the conversion via 1H NMR.
Each reaction is performed in triplicate.
General Procedure [4]
As the pressure builds, the solid
dry ice melts to form liquid CO2.
The liquid CO2 boils, and the gas
slowly escapes from the tube.
CO2 Phase Diagram [5]
(salen)AlCl
nBu4NBr
Previous Work from the Poland Lab
Catalyst Cocatalyst Conversion (%)
none none 0.0
none
1 mol%
nBu4NBr
0.4 ± 0.1
none
2 mol%
nBu4NBr
0.8 ± 0.1
Jacobsen’s
ligand
2 mol%
nBu4NBr
0.0
Aluminum
powder
2 mol%
nBu4NBr
0.0
Comparing (salen)AlCl and [(salen)Al]2O Systems
86% crude
yield
50°C water bath, 10 min reactions
1.0 mL of epichlorohydrin, all run in triplicate
▪ [(salen)Al]2O system can be recycled, and conversion
increases for all systems until cocatalyst loading is 4
mol% nBu4NBr
▪ On average, conversions remain within error as
nBu4NBr loading increases from 2 mol% to 4 mol%
▪ Provided sufficient nBu4NBr, [(salen)Al]2O systems
perform better repeated runs than (salen)AlCl systems
▪ 2 mol% nBu4NBr is lowest and most sufficient loading
to maximize conversion to epichlorohydrin carbonate
▪ Maximum ~27% conversion after three repeated runs
utilizing 0.5 mol% [(salen)Al]2O and 2 mol% nBu4NBr Experimental costs dropped
35% even after inclusion of
[(salen)Al]2O synthesis.
▪ Resulted in 86% crude yield of
[(salen)Al]2O
▪ [(salen)Al]2O can be synthesized for
~$37/g
▪ Impure catalyst characterization via 1H
and 13C NMR spectroscopy
▪ [(salen)Al]2O is unstable on silica gel –
column chromatography not feasible
for separation
▪ Mass spectroscopy possible but not
completed
▪ Employing [(salen)Al]2O as catalyst in experiment with
complex synthesis reduces costs from $6.73 to $4.41
compared to (salen)AlCl
▪ Synthesis of [(salen)Al]2O plus use of catalyst in
coupling reaction could be interesting and engaging
upper-level Inorganic multi-week experiment
▪ Experimental cost could be even further reduced using
catalysts like zinc octoate
Challenge: Experimental Cost [3]
Material Cost ($)
Two Centrifuge Tubes 1.30
2 mL epichlorohydrin 0.14
1% (salen)AlCl 5.22
2% nBu4NBr 0.07
TOTAL $6.73
Lab experiment to use one control
reaction and two catalytic repeated runs
▪ Conversions of 9.5 ± 1.1% reached using
epichlorohydrin as epoxide
▪ 10-minute reactions are optimal for conversion
to cyclic carbonate products
▪ Utilizing 1 mol% (salen)AlCl and 2 mol%
nBu4NBr yields 9.5 ± 1.1% epichlorohydrin
carbonate in just 10 minutes
▪ System can be rerun with fresh dry ice up to
5× to increase yields to >25%
▪ Experiment could be cost-prohibitive at many
institutions.
Figure 1. Comparison of catalytic performance of 1 mol% (salen)AlCl with
different loadings of cocatalyst nBu4NBr and different reaction times.
1. Set up dried reflux glassware using Schlenk
line flushed with N2
2. Add shredded Al foil and I2 crystal to round-
bottom flask
3. Cannulate dry ethanol and dry toluene into
round-bottom flask
4. Degas flask and dissolve Jacobsen’s catalyst
using dry toluene
5. Cannulate dissolved ligand into round-bottom
flask
6. React overnight at reflux to produce yellow
and brown solid
7. Purify via liquid-liquid extraction with water and
filtration through celite and vacuum
Preliminary Control Experiments
▪ Control experiments without catalyst
and/or cocatalyst resulted in little to no
conversion
▪ Starting material of [(salen)Al]2O
synthesis also show no conversion to
epichlorohydrin carbonate
More Cost-Effective Option?
▪ Explore reaction with different epoxides, e.g. butylene oxide
▪ Refine synthesis of [(salen)Al]2O for undergraduate laboratory
▪ Further purification and characterization methods for [(salen)Al]2O
Δ
, N2
Jacobsen’s Ligand
[(salen)Al]2O Synthetic Scheme
Updated Experimental Cost [3]