Solubility of Bio-Sourced Feedstocks in ‘Green’ Solvents
CGCC
Centre for
Green
Chemistry
and
Catalysis
Samantha Payne and Fran Kerton*
Department of Chemistry, Memorial University of Newfoundland,
St. John’s, NL, Canada, A1B 3X7
1
Project Overview:
O
O
O
O
2
HO
OH
A group of 14 different bio-sourced, renewable feedstocks have been
examined for their solubility/miscibility in a variety of ‘green’ solvents,
and trends in solubility have been assessed so that the data may be
extrapolated to help predict solubilities of other related compounds. This
information could provide valuable insight into the workability of a host of
new, green reactions using these compounds, opening the door to a
realm of more environmentally friendly syntheses.
Homoserine
O
NH2
O
Aspartic Acid (P)
O
6
5
OH
7
O
O
Oxalacetic Acid (P)
O
OH
Tartaric Acid
O
24 h
< 1 min
1 min
1 min
1 min
Miscible
Miscible
-
12
O
HO
11
HO
OH
3-Hydroxybutyrolactone (P)
OH
OH
OH
14
Miscible
Miscible
-
OH
OH
HO
HO
OH
Miscible
Miscible
-
OH
OH
Most modern organic chemicals are
made from non-renewable feedstocks,
leading to environmental concerns and
a need for bio-sourced, renewable
feedstocks capable of conversion into
these chemicals. Another important
consideration is the way in which the
reaction is carried out – how ‘green’ is
the overall process? With these two
factors in mind, an understanding of
feedstock solubility in a variety of
different solvents would be a valuable
asset.
OH
Solubility of xylitol, 12, and D-xylose, 16 in ILs, in comparison to
solubilities of 6-carbon sugars
‘Green’ Solvents:
IL
Solubility at 100 °C (g/g)
12
16
[PR4]DBS
Not Soluble
0.1294 ± 0.0085
BMImPF6
0.0244 ± 0.0095 0.0230 ± 0.0035
BMImCl
0.1529 ± 0.0083 0.0820 ± 0.0275
ChoCl/Oxalic Acid 0.0290 ± 0.0014 0.0658 ± 0.0067
ChoCl/Citric Acid 0.0378 ± 0.0055
Not Soluble
Water: Both abundant and benign, its solvating
properties can be altered through changes in
pH, temperature, and pressure.
scCO2: Also abundant and non-toxic,
possesses low viscosity and high diffusivity . Its
solvating properties can be altered through
changes in temperature and pressure, or by
addition of a co-solvent.
The two liquid samples studied, 10 and 11, exhibited universal
solubility over the entire range of ‘green’ solvents examined.
Furthermore, 15 is also soluble in scCO2 and provides a useful
working hypothesis that bio-sourced molecules with low melting points
(at or below 30 °C) will dissolve in this green solvent. The dicarboxylic
acids, 6-9, proved to be the next most soluble group of compounds,
being soluble in all media except neat scCO2. The acids containing CC double bonds, 4 and 5, were also widely soluble and demonstrated
solubilities comparable to that of the previous group, except in the
case of neutral water. The polyols, 12-14 (and homoserine, 1)
displayed aqueous solubility over a range of pHs, and were also found
to be soluble in ILs. Finally, the amino acids (2 and 3) showed the
smallest span of solubility, being insoluble in all the solvents studied,
except for water, and even then only with modified pH.
Background:
Sorbitol (P)
Mannitol
Observed Trends and Conclusions:
OH
Xylitol (P)
OH
Chloroform Diethyl ether
OH
HO (liquid)
O
Levulinic Acid (P)
O
Malic Acid (P)
OH
O
13
24 h
24 h
< 1 min
1 min
< 1 min
< 1 min
Miscible
Miscible
-
O
10
Solubility data for bio-sourced molecules in aqueous solution, alcohols, chloroform and
diethyl ether
1
2
3
4
5
6
7
8
9
10
11
12
13
14
OH
HO
O
Succinic Acid (P)
Ethanol
8
HO
HO
Fumaric Acid (P)
OH
OH
(liquid)
Water, pH
9.6
< 1 min
< 1 min
< 1 min
2 min
3 min
< 1 min
< 1 min
< 1 min
< 1 min
Miscible
Miscible
< 1 min
< 1 min
< 1 min
2,5-Furandicarboxylic Acid (P)
O
HO
HO
LogPoct/wat Water, pH Water, pH
7
4.7
2.19, 9.21
-2.785
< 1 min
< 1 min
2.13, 4.31. 9.58
-3.386
1.99, 3.90, 9.90
-3.236
24 h
2.60, 3.55
-0.913
2 min
3.03, 4.44
-0.748
2 min
2.22, 3.89, 13.03
-1.600
< 1 min
< 1 min
2.98, 4.34
-2.459
< 1 min
3.40, 5.11
-1.984
< 1 min
< 1 min
4.16, 5.61
-0.590
1 min
< 1 min
4.62
-0.490
Miscible Miscible
12.87
-1.901
Miscible Miscible
13.70
-2.068
< 1 min
< 1 min
13.50
-3.100
< 1 min
< 1 min
13.00
-2.912
< 1 min
< 1 min
OH
OH
OH
OH
pKa
HO
NH2
9
Compound
O
O
O
Solvents
Methanol
OH
HO
OH
Glutamic Acid (P)
NH2
4
3
HO
O
O
IL
[PR4]Cl
BMImPF6
BMImCl
Solubility at 30 °C (g/g)
Glucose
Fructose
0.0469
< 0.0004
0.5233
ILs: Consist entirely of ions, have melting
points below 100 °C, and exhibit no detectable
vapour pressure below their temperature of
thermal decomposition. Versatile, with the
potential for tuning of various properties.
Increasing polarity
scCO2
scCO2 +
ROH
EtOH
H2O
pH=9.6
MeOH
O
Liquids: Levulinic Acid
& 3-Hydroxybutyrolactone
H2O
pH=7
H2O
pH=4.7
O
Temperature-pressure phase diagram for levulinic
acid, 10, 3-hydroxybutyrolactone, 11 and 5hydroxymethylfurfural, 15 in neat carbon dioxide.
Error bars omitted for clarity, pressure  0.3 to 2.1
bar.
ILs
O
HO
O
HO
Dicarboxylic Acids: Oxalacetic Acid, Tartaric Acida, Malic Acid, Succinic Acid
O
O
OH
O
OH
OH
HO
HO
O
15
OH
HO
N
O
N
Cl
Double-bond Containing
Compounds: Fumaric Acid
& 2,5-Furandicarboxyic Acidb
N
-
PF6-
OH
OH
HO
HO
O
O
N
O
OH
O
O
O
O
O
O
OH
O
HO
HO
OH
O
O
Homoserine, and Polyols: Xylitol,
Mannitol, Sorbitol
OH
5-HMF
OH
1-butyl-3-methylimidazolium chloride
[BMIm]Cl
[BMIm]PF6
OH
OH
HO
O
OH
HO
OH
OH
OH
O
OH
OH
HO
OH
16
O
OH
O
O
HO
N
Xylose
OH
Aspartic
Acid
OH
HO
O
Glutamic
Acid
Polysaccarides,
etc.
(eg. cellulose)
Amino Acids
HO
HO
OH
OH
Choline Chloride
OH
O
NH2
OH
HO
OH
NH2
Cl
OH
OH NH2
OH
OH
OH
O
O
-
OH
HO
Citric Acid
a
O
Oxalic Acid
Tartaric acid not soluble in pH 4.7
b Furandicarboxylic acid not soluble in EtOH
Temperature-pressure phase diagram for biosourced carboxylic acids 4-9 in carbon
dioxide/methanol. Error bars omitted for clarity,
pressure  0.3 to 3.4 bar.
References:
Cloud point for tartaric
acid in scCO2/MeOH
• J. H. Clark and F. E. I. Deswarte, Introduction to Chemicals from Biomass, John Wiley & Sons Ltd., Chichester, UK, 2008
• CRC handbook of chemistry and physics, 84th edition, CRC Press, Boca Raton, Florida, 2003
• Data for biochemical research, 3rd edition, Oxford University Press, New York, New York, 1986
• A. A. Rosatella, L. C. Branco and C. A. M. Afonso, Green Chem. 2009, 11, 1406
• R. P. Swatloski, S. K. Spear, J. D. Holbrey and R. D. Rogers, J. Am. Chem. Soc., 2002, 124, 4974
• J. M. DeSimone and W. Tumas, Green Chemistry Using Liquid and Supercritical Carbon Dioxide, Oxford University Press,
Oxford, 2003
• P. Wasserscheid and M. Haumann, in Catalyst Separation, Recovery, and Recycling: Chemistry and Process Design, ed. D. ColeHamilton and R. Tooze, Springer, Netherlands, 2006, volume 30, chapter 7, pp. 183-213
Acknowledgements Green Chemistry and Catalysis Group and the
Funding provided by:
Memorial Department of Chemistry