Renewable Self-Blowing Non-Isocyanate Polyurethane Foams from Lysine and Sorbitol

Article abstract of DOI:10.1002/ejoc.201800665

Copolymerisation of a sorbitol-derived bis-carbonate with simple diamines, including cadaverine that was sustainably produced from lysine, under solvent-free conditions was shown to produce rigid foams. Thermogravimetric analysis carried out in tandem with infrared spectroscopy of the released gases confirmed that the foaming agent was carbon dioxide produced during the polymerisation process itself. Such a bio-based foam, being made under mild conditions from stable, benign precursors, with no toxic isocyanates, has great potential application for both thermal insulation and packaging.

Full text of DOI:10.1002/ejoc.201800665

A Journal of
Accepted Article
Title: Renewable Self-Blowing Non-isocyanate Polyurethane Foams
from Lysine and Sorbitol
Authors: James Clark, thomas farmer, Ian Ingram, Yann Lie, and
Michael North
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201800665
Link to VoR: http://dx.doi.org/10.1002/ejoc.201800665
Supported by

10.1002/ejoc.201800665
European Journal of Organic Chemistry
FULL PAPER
Renewable Self-Blowing Non-isocyanate Polyurethane Foams
from Lysine and Sorbitol
James H. Clark,[a] Thomas J. Farmer,[a] Ian D. V. Ingram,[a] Yann Lie[a] and Michael North*[a]
Abstract: Copolymerisation of a sorbitol-derived bis-carbonate with
simple diamines, including cadaverine that was sustainably
produced from lysine, under solvent free conditions was shown to
produce rigid foams. Thermogravimetric analysis carried out in
tandem with infrared spectroscopy of the released gases confirmed
that the foaming agent was carbon dioxide produced during the
polymerisation process itself. Such a bio-based foam, being made
under mild conditions from stable, benign precursors, with no toxic
isocyanates, has great potential application for both thermal
insulation and packaging.
carbon dioxide incorporated into the material itself.[5]
Over recent years, as well as addressing polyol
sustainability, research has focused on routes to polyurethanes
which avoid isocyanates entirely.[6] The most significant
chemistry to achieve this has been the copolymerisation of a bis-
cyclic carbonate with a diamine to give polyhydroxyurethanes
(Scheme 1).[7] Five membered cyclic carbonates are attractive
monomers as they are usually non-toxic; indeed, propylene
carbonate is considered safe enough to find widespread use in
cosmetics.[8] In the most sustainable scenario, cyclic carbonates
can be derived from biomass either by epoxidation of olefins and
reaction of the resulting epoxide with carbon dioxide in the
presence of a suitable catalyst,[9] or by transesterification of a
bio-based diol with dimethyl carbonate,[10] which is widely
considered to be a “green” reagent.[11] From a sustainability
standpoint, the use of phosgene to convert diols to cyclic
carbonates, whilst effective, is ruled out by toxicity and atom
economy considerations.
Introduction
Polyurethanes are widely used polymers, both in coatings and
varnishes, and as foams for insulation applications. Most
commonly, these materials are made by combining a polyol,
often
a polyether, with a diisocyanate. Isocyanates are
extremely toxic, with the most serious chemical accident in
history, the Bhopal disaster, being the result of a release of
methyl isocyanate.[1] Although less hazardous than methyl
isocyanate due to their lower volatilities, the toluene
diisocyanate or methyl diisocyanates used in the polyurethane
industries are considered to be a concern, especially for workers
at polyurethane plants.[2] Additionally, for foam applications, a
gas must be generated in-situ, often by the injection of water
which reacts with some of the isocyanate to yield carbon dioxide.
Clearly, therefore, a more sustainable and safer route to
polyurethanes is very desirable. To date, a significant amount of
work has been done to achieve renewable (or partially
renewable as they tend to be used in blends) polyol
components,[3] and several of these have become commercially
successful. Most notably, the Ford motor company have been
using soybean oil derived foams in their car upholstery for more
than a decade.[4] Researchers also recently evaluated the
environmental impact of partially replacing propylene oxide in
poly(propylene oxide) polyols with carbon dioxide to form
poly(ether carbonate) copolymer polyols, Covestro’s pioneering
“dream process”, concluding that the most significant impact
was made by using less propylene oxide, rather than by any
Scheme 1. Synthesis of polyhydroxyurethanes from cyclic carbonates and
diamines.
Sorbitol
1 is an attractive feedstock for sustainable
polymers as it is readily available at low cost by reduction of
glucose.[12] It is non-toxic, and is commercially produced for use
as a sweetener and as a thickening agent in many food and
cosmetic formulations. Partial dehydration of sorbitol leads to
sorbitan 2, esters of which are important non-ionic and non-toxic
surfactants (known commercially as “Spans”) used as
emulsifiers in personal care formulations. Sorbitan possesses
two diol moieties which suggests the possibility of preparing the
corresponding sorbitan bis-carbonate 3 via transesterification
with dimethyl carbonate. Indeed, Rokicki’s group, reported that
bis-carbonate 3 can be prepared directly from sorbitol 1 by
reaction with dimethyl carbonate and catalytic base, without the
need to first prepare the sorbitan intermediate (Scheme 2).[13]
The same group subsequently reported the formation of low
molecular weight oligomers by the solution phase polymerisation
of bis-carbonate 3 and petrochemically derived diamines. The
[a]
Prof. J. H. Clark, Dr. T. J. Farmer, Dr. I. D. V. Ingram, Mr. Y. Lie and
Prof. M. North
Green Chemistry Centre of Excellence
Department of Chemistry
University of York
York, YO10 5DD, UK
E-mail: michael.north@york.ac.uk;
https://www.york.ac.uk/chemistry/staff/academic/h-n/mnorth/
Supporting information for this article is given via a link at the end of
the document.
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10.1002/ejoc.201800665
European Journal of Organic Chemistry
FULL PAPER
oligomers were then treated with a six-membered ring bis-
monomer unit (four different ring-opened repeat units are
carbonate
to
form
poly(carbonate-urethanes).
These
possible from bis-carbonate 3 as shown in Figure 2).
polymerisations were however carried out in DMF, a solvent
which is known to be reprotoxic and a substance of high concern
under REACh regulations.[15]
Precipitation of the polymer from DMSO solution into ethyl
acetate successfully removed residual monomer, but the
complexity of the resulting NMR spectra was still such that end-
groups could not be identified, preventing an estimate of
molecular weight being made by this method.
Scheme 2. Synthesis of polyhydroxyurethanes from sorbitol derived bis-
carbonate 3.
In this paper we show that monomer 3 can also be
polymerised under solvent-free melt polymerisation conditions
and that this results in the unique formation of rigid foams
without the need for any additional blowing agent. This route is
complimentary to post-polymerisation foaming methods, such as
those using rapid expansion of the polymer with supercritical
carbon dioxide.[16] In addition we show that a wholly bio-based
polyhydroxyurethane can be prepared by this methodology by
utilising pentamethylene diamine (cadaverine) obtained by the
decarboxylation of lysine.
Figure 1. Hot stage microscope images showing the evolution of bubbles
(black) in the reaction mixture during the first minute of heating. Red scale
bars are 100 µm.
Results and Discussion
Thermal analysis (Figure 3) by thermogravimetric analysis
(TGA) and differential scanning calorimetry (DSC) revealed that
the foamed material was relatively thermally stable, having a
T10% (the temperature at which 10% of the initial mass was lost)
of 205 °C. The DSC trace showed an exothermic feature at
180 °C, possibly due to a crystallization, and a low-temperature
feature at -6 °C similar to a glass transition. This might represent
a glass transition in some low molecular weight oligomers within
the polymeric material as the bulk polymer is a hard material at
room temperature, making a genuine below-room-temperature
Tg implausible.
An initial hypothesis was that the foaming was the result of
some of the bis-carbonate monomer undergoing decarboxylation
under the reaction conditions. However, thermogravimetric
analysis of compound 3 revealed it to be stable at 100 °C, and
indicated that the foaming must instead be due to a side reaction
during the polymerisation. To identify the gas responsible for the
foam formation, thermogravimetric analysis of the polymerisation
mixture in tandem with infra-red spectroscopy of the gases
released was carried out. At temperatures relevant to the
polymerisation, carbon dioxide release was observed (Figure 4),
along with a small amount of sublimation of HMDA, which could
Sorbitan bis-carbonate was produced by the method reported by
Rokicki[13] using methanol as solvent and was purified by first
washing with warm acetone, and then recrystallisation from
water to give fine white crystalline needles. When equimolar
amounts of bis-carbonate
3 and hexamethylene diamine
(HMDA) were ground together and then heated at 100 °C, a rigid
foamy material was obtained and gas evolution was observed.
The foaming reaction was observed by hot-stage microscopy to
occur immediately upon heating the thoroughly mixed
monomers (Figure 1). NMR spectroscopy indicated that the
monomers had been consumed and that the polymer contained
both sorbitan and HMDA derived units (see supporting
information). Three urethane NH signals were clearly present at
7.0-7.5 ppm and the hexamethylene units could be identified at
2.9 and 1-1.5 ppm. Unfortunately, all of the sorbitan CHO
signals appeared as a single multiplet between 3.4 and 4.1 ppm
which prevented
a detailed analysis of the stereo- and
regiochemistry of the polymerisation. Never the less, the
presence of three NH signals is suggestive that the ring-opening
of bis-carbonate 3 is not completely regiospecific and the
polymer is likely to contain more than one sorbitan derived
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10.1002/ejoc.201800665
European Journal of Organic Chemistry
FULL PAPER
also be seen condensed on the sides of the reaction vessel
when the polymerisation was carried out on a preparative scale.
under the reaction conditions. However, when the two
monomers were ground together and held at 100 °C in the TGA
apparatus under a flow of nitrogen, only a constant and very
slight mass loss was observed, which was ongoing for at least
20 hours, making it apparent that the released carbon dioxide
was trapped within the foam and was not readily released upon
standing. Analysis of foams prepared in preparative reactions,
by collapsing the foam structure using methanol to release
trapped carbon dioxide and removing solvent thoroughly under
vacuum, proved irreproducible. However, polymerisation under
Figure 2. Structure of the polymer obtained from monomers 3 and HMDA
showing the four possible repeat units obtained by ring-opening of monomer 3.
Having confirmed that the foaming gas was carbon dioxide,
its formation can be explained by a side reaction where the
addition-elimination step of the amine reacting with bis-
carbonate 3 is followed by cyclisation of the resulting primary
hydroxyl group to give an isosorbide type structure with release
of carbon dioxide (Scheme 3). Evidence to support this
mechanism came from model reactions under the same reaction
conditions between bis-carbonate 3 and one or two equivalents
of n-dodecylamine, used as an analogue for the amino terminus
of a growing polymer chain. Isosorbide derivative 4 was
detected by mass spectrometry in these control experiments. In
addition, analysis of the HMDA-Sorbitan bis-carbonate polymer
by MALDI mass spectrometry showed several series of peaks
spaced with the expected repeat unit corresponding to various
combinations of end-groups including sorbitan diols, amines and
carbonates. It is difficult to determine whether this side-reaction
is end-capping or if the resulting alcohol acts as a nucleophile
and becomes incorporated into the polymer chain. Infrared
spectroscopy on the polymer showed carbonyl signals only for
urethanes (1690 cm-1) and a small amount of residual starting
carbonate (1779 cm-1) (Figure 5).
Figure 3. Thermogravimetric analysis (top) and differential scanning
calorimetry (bottom) of polyhydroxyurethane derived from sorbitol bis-
carbonate 3 and hexamethylene diamine.
An attempt was made to quantify the amount of carbon
dioxide released during polymerisation, and thus the extent of
the end-capping side reaction, by thermogravimetric analysis
Scheme 3. Generation of carbon dioxide during reaction of bis-carbonate 3
with amines.
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10.1002/ejoc.201800665
European Journal of Organic Chemistry
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vacuum to remove carbon dioxide as it was formed gave more
consistent results, with 6.5-8% of the total mass (relative to the
monomers) being lost after heating at 100 °C overnight. Whilst
some of this mass can be ascribed to loss of HMDA (see TG-IR
in Figure 4), this nevertheless provides an upper limit on the
stoichiometry of the foaming reaction of approximately one
carbon dioxide released for every two equivalents of bis-
carbonate monomer 3 polymerised, under non-stirred conditions,
which is consistent with the molecular weights of the oligomers
observed in MALDI.
To better understand the polymerisation and to evaluate
the influence of monomer mixing, polymerisations were carried
out in
a Brookfield viscometer and the viscosity of the
polymerising mixture was monitored (Figure 6). It is worth noting
that Figure 6 shows the apparent viscosity, as the presence of
bubbles leads to a lower measured value. As might be expected,
viscosity increases over time with increased degree of
polymerisation, reaching a peak after roughly two hours. The
apparent viscosity then decreased significantly, probably as a
result of continued foaming beyond the point at which polymer
growth had largely ceased, before stabilising at a value
substantially below the maximum in a little under three hours.
These samples appeared to contain bubbles which were
persistent even under continual shearing.
Figure 4. Thermogravimetric analysis of
a 1:1 mixture of sorbitan bis-
carbonate and HMDA (top) with the infra-red spectrum (bottom) corresponding
to the spectrum of the gases released at the temperature marked with the
dashed red line.
Figure 6. Plot of measured viscosity against time for the copolymerisation of
sorbitan bis-carbonate 3 with HMDA at 100 °C at a shear rate of 0.8 s-1.
Whilst HMDA is derivable from biomass via
hydroxymethylfuran, it has been argued that the bio-based
routes to it are neither economically nor environmentally
superior to the conventional fossil-based route.[17] Therefore it
was decided to investigate the use of cadaverine 5 which can be
prepared by the decarboxylation of lysine (Scheme 4) in order to
demonstrate this polyhydroxyurethane production with fully-
biobased monomers. Lysine is already produced on a large
scale at low cost by fermentation for use as an animal feed
supplement,[18] and as a dietary supplement for humans. It is
therefore a promising feedstock for diamines. Amino acids such
as lysine can also be sourced from protein hydrolysate and the
development of bio-refineries will generate large amounts of
protein-rich residues that may not be suitable for use as
foodstuffs due to the presence of other species.
Figure 5. Infra-red spectrum (ATR-FTIR) of the polyhydroxyurethane
produced from sorbitan bis-carbonate and HMDA indicating the carbonyl
signals for both urethane linkages of the polymer backbone, and a small
amount of residual cyclic carbonate.
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The decarboxylation of L-lysine 6 to cadaverine 5 has
been previously described by Omeis,[19] Hashimoto[20] and
Jackson,[21] although all these methods suffer from limitations
that reduce their acceptability as clean production pathways. In
the 2009 patent by Omeis, isophorone 7 is utilised as an -
unsaturated carbonyl compound to induce the decarboxylation
of a range of L-lysine derivatives.[19] Although this protocol has
the advantage of being a continuous distillation process, it omits
recovery of the isophorone and requires the use of high boiling
point solvents such as isononanol and dibenzyltoluene.
Additionally, although the patent claims the method is applicable
to other amino acids, only the example of L-lysine presented.
The method of Hashimoto uses 2-cyclohexen-1-one 8 as the
-unsaturated carbonyl compound, and was demonstrated for
a range of amino acids, including L-lysine. Again however, there
is no evidence of recovery of compound 8, indeed no work-up is
described, and cyclohexanol is used as the solvent over long
reaction times (3 hours for L-lysine). A more recent method
reported by Jackson et al. further developed the Hashimoto
method by using microwave irradiation at 190 °C to reduce
reaction times, whilst also finding that bio-derived (R)-carvone 9
was an effective decarboxylation inducer, having a similar
reactivity to 8.[21] Again, no recovery and reuse of the carvone
was attempted, with the authors describing how the (R)-carvone
was found to convert to inactive carvacrol 10 during the process.
Initially, the three previously described cyclic enones 7-9
were compared following a modified version of Jackson’s
microwave procedure for the production of cadaverine
dihydrochloride 5 (Scheme 4 and Table 1). For the washing of
the aqueous phase during the work-up, diethyl ether was
substituted with safer ethyl acetate and a trituration with n-
propanol was added to improve the purity of the isolated product
5. Under these conditions, yields of compound 5 were similar
with all three catalysts (31-37%, Table 1). However, both
compounds 8 and 9 proved impossible to reuse for subsequent
reactions. In the case of compound 9, whilst some excess
catalyst could be recovered, the material that had actually
participated in the reaction was converted to carvacrol 10. An
89% conversion of 9 into 10 under these conditions was
observed by gas chromatrography (see supporting information).
Compound 8 was also unrecoverable from the reaction mixture,
forming an insoluble, waxy, byproduct which is believed to be
the result of either an aza-Michael addition reaction with lysine
or cadavarine, or polymerisation of the -unsaturated carbonyl
compound. These issues with the recovery of enones were also
reported by Jackson.[21] By contrast, isophorone 7 is not
susceptible to aromatization, due to the dimethyl substituents at
the 5-position, and has reduced susceptibility to aza-Michael
addition due to the methyl substituent at the 3-position.
Isophorone 7 was found to be both recoverable, and reusable in
this reaction, with the organic phase isolated during the work-up,
when dried and concentrated, being able to induce a second
reaction directly with only slightly reduced yield (27%). Therefore,
of the enone systems tested, isophorone 7 is clearly the more
sustainable choice in this case.
analysis (Figure 7) showed that the polymer also had similar
stability to that prepared from HMDA, with a T10% of 193 °C.
Differential scanning calorimetry was also similar to the HMDA
polymer, with a high temperature crystallisation event at 190 °C,
and a small, low temperature Tg-like feature at -31 °C. As for the
HMDA derived polymer, this foam was rigid at room temperature,
making a true Tg below room temperature unlikely. Also
similarly to the HMDA polymer, infra-red spectroscopy showed
carbonyl signals consistent with urethanes (1688 cm-1) and a
small amount of residual carbonate (1779 cm-1) (Figure 8).
Scheme 4. Decarboxylation of L-lysine 6 to cadaverine dihydrochloride 5
using organocatalysts 7-9.
Table 1. Isolated yields and description of organocatalyst recovery for the
decarboxylation of of L-lysine 6 to cadaverine dichloride salt 5.[a]
Isophorone
2-Cyclohexene-1-one
(R)-Carvone
7
8
9
31 %
32 %
37 %
Yield (%)
Easy and
straight-
forward
Not possible –
insoluble material
formed
Possible to
recover excess
prior to imine-
hydrolysis step,
but any formed
from the imine
converts to
Catalyst
recovery
carvacrol 10
[a] Reaction conditions: 5 mmol L-lysine, 3 mL n-propanol, 10 mmol
carbonyl catalyst, 190 °C, 3 min ramp followed by 15 min hold time
followed by addition of 10 mL 2 M HCl and heated until 190 °C reached (no
hold time).
Cadaverine
obtained
by
desalting
cadaverine
hydrochloride prepared from L-lysine, by reaction with excess
sodium hydroxide and extraction with ethyl acetate gave a
similar result to that obtained using commercial cadaverine free
base. Encouraged by this, we also attempted to prepare a foam
by directly reacting the cadaverine hydrochloride with sorbitan
bis-carbonate 3 in the presence of stoichiometric base. This also
produced a rigid foam of similar appearance; however, the salt
content of this material made it very hygroscopic, resulting in
formation of a deliquescent foam that collapsed upon standing in
moist air over the course of a day.
Initially, the preparation of a poly-hydroxyurethane from
commercial cadaverine free base was investigated. Sorbitan bis-
carbonate 3 was found to react with this cadaverine to give a
rigid foam very similar to that obtained with HMDA. This foam
showed the expected repeat unit by MALDI-MS with end groups
similar to those observed for the HMDA variant. Thermal
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10.1002/ejoc.201800665
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We have shown that, when prepared under solvent-free
conditions, isocyanate free polyhydroxyurethanes prepared from
a diamine and sorbitan bis-carbonate spontaneously liberate
carbon dioxide, forming
a rigid foam. This self-foaming
behaviour is not only a significant improvement in sustainability
over preparation of foams by addition of a foaming agent, and
especially over the hydrolysis of excess isocyanate as is used
commercially to foam conventional polyurethanes, but is also
very efficient, with the carbon dioxide produced largely
remaining trapped within the bubbles rather than being released
into the atmosphere. Both monomers required for the synthesis
of these polyhydroxyurethane foams were prepared from bio-
based starting materials. As the monomers used to prepare
these materials are bio-based, inexpensive, and of low-toxicity,
this type of material shows promise for insulation and packaging
applications.
Experimental Section
Materials
D-sorbitol, dimethyl carbonate, hexamethylenediamine, lysine (>98%)
and cadaverine were purchased from Sigma Aldrich and used as
supplied. Sorbitan bis-carbonate was prepared according to the literature
procedure,[14] recrystallised from water to give white needle crystals, and
dried thoroughly under vacuum before use. Isophorone was vacuum
distilled using a Kugelrohr short-path distillation apparatus and stored in
a sealed vial at 4 °C prior to use.
Instrumentation
Nuclear magnetic resonance spectroscopy was carried out using a JEOL
400 MHz instrument in deuterated dimethyl sulfoxide. MALDI mass
spectrometry was performed on a Bruker solariX XR FTMS 9.4T
instrument, with the plates loaded in methanol using dihydroxybenzoic
acid (DHB) as the matrix. Viscometry was carried out using a Brookfield
R/S plus rheometer fitted with a C50-1/3 cone. Thermogravimetric
analysis (TGA) was carried out using a PL Thermal Sciences STA 625
instrument from ambient (22 °C) to 600 °C at a ramp rate of 10 degrees
per minute in an open aluminium sample pan under N2. TG-IR was
carried out using a Netsch STA409 linked to a gas cell in a Bruker
Equinox 55 Infra-red spectrometer by a heated gas line. Differential
scanning calorimetry (DSC) was carried out using a TA Instruments
MDSC Q2000 instrument in a closed aluminium sample pan under N2.
Figure 7. Thermogravimetric analysis (top) and differential scanning
calorimetry (bottom) of PHU derived from cadaverine 5 and carbonate 3.
Typical polymerisation procedure
Hexamethylene diamine (0.102 g, 1.0 mmol) and sorbitan bis-carbonate
3 (0.216 g, 1.0 mmol) were placed into a small agate mortar and ground
together thoroughly for several minutes until a completely homogeneous
gummy mixture was formed. This mixture was transferred to a glass vial
and heated for 20 hours at 100 °C, giving a rigid, colourless, foamy
material.
Preparation of cadaverine by decarboxylation of L-lysine
L-Lysine (0.73 g, 5.0 mmol) was mixed with of 1-propanol (3 mL) and of
vacuum-distilled isophorone (1.5 mL, 10 mmol). A magnetic stirrer was
then added and the vial was placed in a CEM discover microwave
chamber. The temperature was set at 190 ºC and was reached within 3
min. The temperature was held for 15 minutes. After this first heating,
HCl was added (10 mL of a 2 M solution, 4 eq.). The vial was returned to
the microwave chamber and subjected to a second heating step until 190
ºC was reached, then immediately allowed to cool to room temperature.
The reaction was then washed with EtOAc (1x25 mL), the water phase
was then collected and the organic phase was washed with 2 M HCl (10
mL) and water (10 mL). The collected aqueous phases were washed with
EtOAc (2x25 mL) and the solvent removed in vacuo. The resulting light
brown oil was triturated with 1-propanol to give a solid which was isolated
Figure 8. Infra-red spectrum (ATR-FTIR) of the polyhydroxyurethane
produced from sorbitan bis-carbonate and cadaverine indicating the carbonyl
signals for both urethane linkages of the polymer backbone, and a small
amount of residual cyclic carbonate.
Conclusions
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10.1002/ejoc.201800665
European Journal of Organic Chemistry
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by filtration and dried under vacuum (72 mbar) at 80 ºC for 2 hours to
afford the desired cadaverine dihydrochloride salt as white needle-like
[18] W. Pfefferle, B. M. B. Bathe, A. Marx, Microbial Production of L-Amino
Acids, R. Faurie, J. T., Ed. Springer: Germany, 2003; Vol. 79, p 59.
[19] M. Omeis G. Koehler, M. Neumann, T. Kuebelbaeck, Continuous
Process For Decarboxylating Carboxylic Acids US Patent 7,485,756 B2
2009.
1
crystals (0.287g, 32%). H-NMR (400 MHz, [D2O]): δ 3.01 (t, J = 7.6 Hz,
4H), 1.71 (quintet, J = 7.7 Hz, 4H), 1.46 (quintet, J = 7.9 Hz, 2H). 13C
NMR (101 MHz; [D2O]): δ 39.2, 26.3, 22.7. FT-IR ṽ (cm-1): 2928, 2521,
1568, 1521, 1484, 1400, 1321, 1295, 1175, 1125, 1018, 999, 929, 825,
738. ESI-MS: C5H15N2 103.1230 found 103.1229
[20] Hashimoto, M., Eda, Y., Osanai, Y., Iwai, T., and Aoki, S. A Novel
Decarboxylation of alpha-Amino Acids. Chem. Lett., (C), 1986; 893–
896.
Recycling of isophorone for the preparation of cadaverine by
decarboxylation of L-lysine
[21] D. M. Jackson, R. L. Ashley, C. B. Brownfield, D. R. Morrison, R. W.
Morrison, Synth. Commun. 2015, 45, 2691–2700.
The isophorone recycling experiment was conducted at a 2 mmol scale
using 600 uL of collected organic phases from a first reaction, dried over
MgSO4 and evaporated under reduced pressure. 40% of the isophorone
was recovered and used in a second reaction without further purification
under the same reaction conditions and work-up as described above
(0.095g, 27%).
Acknowledgements
The authors thank the Engineering and Physical Sciences
Research Council (EPSRC) for funding this research through
grant EP/L017393/1.
Keywords: Polyurethanes, foams, renewable materials, sorbitol,
cyclic carbonates
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10.1002/ejoc.201800665
European Journal of Organic Chemistry
FULL PAPER
Entry for the Table of Contents
FULL PAPER
Nothing artificial about this
sweet foam. A bis-carbonate
derived from sorbitol, which is
both non-toxic and bio-derived,
and pentamethylene diamine
produced by the decarboxylation
of lysine, are polymerised to form
a polyhydroxyurethane. The
polymerisation releases carbon
dioxide, resulting in a sustainable
self-foaming material made
James H. Clark, Thomas J.
Farmer, Ian D. V. Ingram, Yann
Lie and Michael North*
Page No. – Page No.
Renewable Self-Blowing Non-
isocyanate Polyurethane
Foams from Lysine and
Sorbitol
entirely without the use of
isocyanates or blowing agents.
Key Topic: Sustainable polyurethane foams
This article is protected by copyright. All rights reserved.