Note: Descriptions are shown in the official language in which they were submitted.
PF 72809-2 CA 02856466 2014-05-21
A
Preparation of 5-hydroxymethylfurfural (HMF) from saccharide solutions in the
presence of a
solvent having a boiling point greater than 60 C and less than 200 C (at
standard pressure,
called low boiler for short)
Description:
The present invention relates to a process for preparing 5-
hydroxymethylfurfural (HMF), which
comprises
a) feeding solutions (hereinafter called starting solution) comprising
- one or more hexoses or oligomers or polymers formed from hexoses
(collectively called
saccharides hereinafter) and
- an organic solvent having a boiling point greater than 200 C (at standard
pressure) (called
high boiler for short) and
- water,
and a solvent having a boiling point greater than 60 C and less than 200 C (at
standard
pressure, called low boiler for short) to a reaction vessel,
b) effecting a conversion of hexose to HMF in the reaction vessel in the
presence of the low
boiler with simultaneous distillative removal of the HMF and
c) obtaining, as the distillate, a dilute solution comprising HMF, water and
low boilers
(hereinafter called distillate).
For chemical syntheses, increasing significance is being gained by compounds
which are
obtained from renewable raw materials and can be converted easily by chemical
reactions to
industrially usable compounds.
In this context, 5-hydroxymethylfurfural (HMF) is known, this being preparable
by different
processes from hexoses or other saccharides. From HMF, for example, 2,5-
furandicarboxylic
acid is easily obtainable, the latter being suitable as a dicarboxylic acid
for preparation of
polymers, such as polyesters or polyurethanes, and can replace other
dicarboxylic acids from
non-renewable raw materials in industrial applications.
HMF is generally prepared by acid-catalyzed dehydration of hexoses such as
glucose or
fructose. The reaction products obtained are acidic solutions which, as well
as the HMF,
comprise unconverted starting materials and/or by-products. In the HMF
synthesis, there is
generally only a partial conversion of the starting materials in order to
avoid the formation of
by-products. In general, the solutions obtained therefore comprise unconverted
starting
materials such as hexoses, or oligomers or polymers formed from hexoses. At
higher
conversions, the amount of by-products increases.
,
PF 72809-2 CA 02856466 2014-05-21
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The removal of the HMF from the reaction solution, which comprises starting
materials or
by-products from the HMF synthesis, is complex and makes it difficult to
obtain HMF.
Feroz Kabir Kazi et al. in Chem Eng. J. 169 (2011), pages 329-338, describe
the separation of
the HMF from the acidic reaction solution by a complex extraction process
using an organic
solvent (butanol); a solution of HMF in butanol is obtained.
DE-A 3601281 discloses a chromatographic removal process in which any organic
solvents are
first removed and the aqueous HMF solution is separated with an ion exchanger
column. The
HMF fraction obtained is crystallized.
A further method of separating HMF from the reaction solution is the
conversion of the HMF to
another, more easily removable compound, optionally followed by a reverse
conversion to HMF
on completion of removal. For instance, HMF, according to Mark Mascal and
Edward B. Nikitin
in 2008 Angew. Chemie Vol. 47, pages 7924-7926, is converted to the more
stable
5-chloromethylfurfural and then back to HMF or derivatives thereof.
Alternatively, the ethers of
HMF are prepared according to EP-A 1834950, or the esters according to EP-A
1834951, these
being directly suitable for further syntheses on completion of removal.
Haru Kawamoto, Shinya Saito et al. describe, in J. Wood Sci. (2007), 53, pages
127-133, the
pyrolysis of cellulose to form levoglucosenone, furfural and/or HMF under
various conditions,
including the supply of water vapor.
FR2663933 and FR2664273 describe how fructose and sucrose are converted to HMF
in a melt
of acidic salts (Na3PO4 and KH2PO4) under the action of superheated steam. A
small portion of
the HMF is entrained by the steam, but the majority of the HMF is subsequently
isolated from
the salt melt by means of extraction.
US4400468 discloses the acidic hydrolysis of biomass under the action of water
vapor to give
sugars, and the direct conversion of the hexose components present in the
mixture to HMF. In
this case, the HMF formed, however, is not isolated in pure form.
HMF should be present in a form of maximum purity for further syntheses.
Aqueous solutions of
HMF suitable for further syntheses are particularly those which comprise by-
products or residual
starting materials in very small amounts at most, if any. Processes known to
date for preparing
HMF or aqueous solutions thereof with sufficient purity are extremely complex.
CN102399203 and Wei et al. in Green Chem. , 2012, 14, pages 1220-1226 disclose
a
distillative process for simultaneous preparation and isolation of HMF by
degradation of fructose
and glucose in ionic liquids. The process comprises the addition of a
saccharide to an ionic
liquid based on imidazolium derivatives, preferably with long alkyl side
chains (e.g. 1-methyl-3-
, PF 72809-2 CA 02856466 2014-05-21
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octylimidazolium chloride) in the presence of a cocatalyst and of a stripping
medium at 100 to
500 Pa, a reaction temperature of 120-180 C and a reaction time of 10 to 60
minutes. The
stripping medium is nitrogen, another inert gas, carbon dioxide, a C1-C8
alkane, acetone or
methyl isobutyl ketone.
The cobalt catalyst used is a metal salt or metal oxide which serves for
stabilization of the HMF
formed, but also serves as a catalyst for the isomerization of glucose to
fructose. Such an
isomerization with metal salts is already known from the literature (Glucose-
isomerization with
Chromium-salts ¨ Science 2007, 316, 1597-1600; Angew. Chem. Int. Ed. 2008, 47,
9345-9348;
Chem. Eur. J. 2011, 17, 5281-5288; Glucose-isomerization with rare-earth
metals - J. Mol. Cat.
A, 2012, 356, 158-164; HMF from Glucose with lanthanides - Green Chem., 2010,
12, 321-325;
Conversion of Cellulose to Furans with metal salts - J. Mol, Catal. A, 2012,
357, 11-18; Sn-Beta
Zeolites -ACS Catal. 2011, 1,408-410).
The use of ionic liquids, especially of substituted imidazolium chloride
derivatives, for the
synthesis of HMF from fructose and glucose is well known in the literature.
However, not only is
the isolation of the HMF formed from the ionic liquid very complex ¨ usually,
the IL is extracted
with an organic solvent, and the reaction in ILs also proceeds much more
slowly in the presence
of water and the saccharide is therefore converted in very substantially
anhydrous IL in all
cases. The latter has to be dewatered in a complex manner prior to further use
(e.g. Blares.
Tech. 2011, 102, 4179-4183).
The adverse effect of water in the reaction medium in the conversion of
sugars, especially
fructose and glucose, to HMF has been adequately described in the literature
(e.g. Carbohydr.
Res. 1977, 54, 177-183; Science 2007, 136, 1597-1600). As is well known to
those skilled in the
art, water firstly slows the dehydration reaction of the sugars, and also
promotes the rehydration
and splitting of the HMF formed to formic acid and levulinic acid (for the
postulated mechanism
of the reaction see Science 2006, 312, 1933-1937). As shown in example 1, the
reaction
proceeds much more slowly with rising water content and gives lower yields of
HMF.
The object of the present invention was therefore an industrial scale process
with which HMF
can be prepared in a very simple and effective manner, HMF is at the same time
obtained in
very substantially pure form, and HMF is therefore separated directly and very
substantially
completely from converted starting materials or by-products.
In industrial scale processes, the conversion is to be performed within an
industrially and
economically advantageous temperature and pressure range with high conversion
and high
space-time yield. More particularly, the use of commercially available aqueous
saccharide
solutions in different concentrations, as opposed to crystalline saccharides,
is of high
significance. Furthermore, the feedstocks should make minimum demands on the
apparatuses
and the procedure, and enable simple purification and isolation of the product
of value. The use
of a gas as a stripping medium in a reaction regime under reduced pressure is
difficult to
, PF 72809-2 CA 02856466 2014-05-21
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implement on the industrial scale since a high pump output is required in
order that the desired
vacuum can be maintained. In the case of the industrial scale use of organic
solvents as
stripping media, the high costs and complex recovery thereof are
disadvantageous. In the case
of preparation of HMF, moreover, short residence times at high temperatures
are highly
advantageous due to the instability of the product. Especially a rapid removal
of the HMF
formed from the reaction solution enables higher yields. A significant factor
in industrial scale
processes is the complexity of the process, such that, for example, one-pot
processes are
preferable for different reasons. A particularly preferred process variant is
reactive distillation, in
which the target product is formed in a one-pot process and is simultaneously
separated from
the reaction solution.
Accordingly, the process defined at the outset has been found.
In the process according to the invention, HMF is prepared in the presence of
a solvent having
a boiling point greater than 60 C and less than 200 C (at standard pressure,
called low boiler
for short) and is separated directly from by-products and unconverted starting
materials of the
HMF synthesis. In contrast to the prior art, this process can be performed on
the industrial
scale.
Process step a)
In process step a), solutions (hereinafter called starting solution)
comprising
- one or more hexoses or oligomers or polymers formed from hexoses
(collectively called
saccharides hereinafter) and
- an organic solvent having a boiling point greater than 200 C (at standard
pressure) (called
high boiler for short) and
- water,
and a solvent having a boiling point greater than 60 C and less than 200 C (at
standard
pressure, called low boiler for short) are fed to a reaction vessel.
The saccharide comprises hexoses, or oligomers or polymers formed from
hexoses. The
hexoses are preferably fructose, glucose or mixtures of fructose and glucose.
Particular
preference is given to fructose or mixtures of fructose with glucose. The
hexose is most
preferably fructose.
The starting solution may also comprise by-products or starting materials from
the preparation
of the saccharides. For example, saccharides can be obtained by degradation of
polymers such
as cellulose or starch. Therefore, the starting solution may still comprise
residual amounts of
such polymers or the oligomeric degradation products thereof.
PF 72809-2 CA 02856466 2014-05-21
The starting solution preferably comprises 1 to 60% by weight of saccharide,
more preferably 10
to 50% by weight of saccharide, based on the total weight of the starting
solution.
The starting solution preferably comprises less than 10% by weight, especially
less than 5% by
5 weight and more preferably less than 1% by weight of by-products or
starting materials from the
preparation of saccharides (based on the total weight of the starting
solution). More particularly,
the starting solution is essentially free of by-products and starting
materials from the preparation
of saccharides.
In an alternative embodiment, the starting solution may also comprise metal
chlorides or metal
nitrates of the general formula MXn as isomerization salts, where M is a
metal, X is chlorine or
nitrate and n is an integer from 1 to 4. These isomerization salts are
preferably present in the
starting solution when the saccharide in the starting solution is glucose or a
saccharide
comprising glucose units, for example sucrose. The use of isomerization salts
has already been
described in the literature (Science 2007, 316, 1597-1600, Carbohydr. Pol.
2012, 90, 792-798,
Chem. Eur. J. 2011, 17, 5281-5288, Green Chem. 2009, 11, 1746-1749).
Preference is given to
using metal chlorides or metal nitrates selected from the group of CrCl2,
CrCI3, AlC13, FeCl2,
FeCI3, CuCI, CuC12, CuBr, VCI3, MoCI3, PdC12, PtC12, RuC13, RhCI3, Ni(NO3)2,
Co(NO3)2,
Cr(NO3)3, SnC14. Very particular preference is given to CrCl2 and CrCI3.
The starting solution further comprises an organic solvent having a boiling
point greater than
200 C (at standard pressure), especially greater than 250 C (called high
boiler for short
hereinafter).
Useful high boilers include hydrophilic solvents; these may be protic,
hydrophilic organic
solvents, for example alcohols, or aprotic hydrophilic solvents, for example
ethers or ketones,
such as dimethyl sulfoxide. Also useful are ionic liquids, high-boiling oils,
for example paraffins,
and high-boiling esters, for example Hexamoll DINCH (diisononyl 1,2-
cyclohexane-
dicarboxylate). Further possible high boilers are: 1,3-dimethylpropyleneurea
(DMPU), tn-n-
oxide (TOPO), hexamethylphosphoramide (HMP), 3-methyl-2-oxazolidone,
2-oxazolidone, o-dihydroxybenzene, catechol, N,N-dibutylurea and dibutyl
sulfone.
High boilers preferred in the context of this invention are polyethers and
ionic liquids.
Polyethers
The polyethers preferably have a melting point less than 60 C, especially less
than 30 C (at
standard pressure, 1 bar). Particularly preferred polyethers are liquid at 20
C (standard
pressure).
The polyethers comprise at least two ether groups. The polyethers preferably
comprise at least
3, especially at least 4 and more preferably at least 6 ether groups. In
general, they comprise
PF 72809-2 CA 02856466 2014-05-21
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not more than 40 and especially not more than 30 ether groups, more preferably
not more than
20 ether groups.
In a particular embodiment, the polyethers do not comprise any heteroatoms
apart from oxygen
in the form of ether groups and optionally hydroxyl groups.
More particularly, the polyethers are aliphatic polyethers, particularly
preferred polyethers being
polyalkylene glycols, where the terminal hydroxyl groups may be etherified
with alkyl groups,
especially C1-C4-alkyl groups.
The alkylene groups of the polyalkylene glycols may, for example, be C2 to C10
and especially
02 to 04 alkylene groups, such as ethylene, propylene or butylene groups. The
polyalkylene
glycols may also comprise various alkylene groups, for example in the form of
blocks.
Very particular preference is therefore given to poly-C2- to -C4-alkylene
glycols, especially
polyethylene glycol, the terminal hydroxyl groups of which may optionally be
etherified with alkyl
groups; the number of repeat alkylene ether groups corresponds to the above
number of ether
groups, the number of repeat alkylene ether groups being especially 4 to 30,
more preferably 6
to 20. The terminal hydroxyl groups of the polyalkylene glycols may be
etherified with alkyl
groups, especially Cl to C4 alkyl groups.
Ionic liquid (IL)
Ionic liquids refer in the context of the present application to organic salts
which are liquid even
at temperatures below 180 C. The ionic liquids preferably have a melting point
of less than
150 C, more preferably less than 120 C, especially less than 100 C.
Ionic liquids which are present in the liquid state even at room temperature
are described, for=
example, by K. N. Marsh et al., Fluid Phase Equilibria 219 (2004), 93-98 and
J. G. Huddleston
et al., Green Chemistry 2001, 3,156-164.
Ionic liquids suitable for use in the process according to the invention are
described in
WO 2008/090155 (page 4, line 38 to page 37, line 31) and WO 2008/090156 (page
7, line 1 to
page 39, line 37), reference being made thereto.
In the ionic liquid, cations and anions are present. Within the ionic liquid,
a proton or an alkyl
radical can be transferred from the cation to the anion, resulting in two
uncharged molecules. In
the ionic liquid used in accordance with the invention, there may thus be an
equilibrium of
anions, cations and uncharged molecules formed therefrom.
Preferred ionic liquids are combinations of nitrogen-containing cation
components (such as
imidazolium derivatives) and halogen ions as anions.
Suitable compounds suitable for formation of the cation of ionic liquids are
described, for
example, in DE 102 02 838 Al ([0030] to [0073]). These compounds preferably
comprise at
least one heteroatom, for example 1 to 10 heteroatoms, which are preferably
selected from
nitrogen, oxygen, phosphorus and sulfur atoms. Preference is given to
compounds which
comprise at least one nitrogen atom and optionally additionally at least one
further heteroatom
PF 72809-2 CA 02856466 2014-05-21
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other than nitrogen. Preference is given to compounds comprising at least one
nitrogen atom,
more preferably 1 to 10 nitrogen atoms, especially 1 to 5 nitrogen atoms, even
more preferably
1 to 3 nitrogen atoms and especially 1 or 2 nitrogen atoms. The latter
nitrogen compounds may
comprise further heteroatoms such as oxygen, sulfur or phosphorus atoms.
Preference is given to those compounds which comprise at least one five- to
six-membered
heterocycle, especially a five-membered heterocycle, which has at least one
nitrogen atom and
optionally an oxygen or sulfur atom. Particular preference is given to those
compounds which
comprise at least one five- to six-membered heterocycle which has one, two or
three nitrogen
atoms and one sulfur or one oxygen atom, very particular preference to those
having two
nitrogen atoms. Preference is further given to aromatic heterocycles.
Preferred cations are unsubstituted or substituted imidazolium ions.
Particularly suitable
imidazolium ions are 1-methylimidazolium, 1-ethylimidazolium, 1-(1-
propyl)imidazolium, 1-(1-
allyl)imidazolium, 1-(1-butyl)imidazolium, 1-(1-octyl)imidazolium, 1-(1-
dodecyl)imidazolium, 1-(1-
tetradecyl)imidazolium, 1-(1-hexadecyl)imidazolium, 1,3-dimethylimidazolium,
1,3-
diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-(1-buty1)-3-
methylimidazolium,1-(1-buty1)-3-
ethylimidazolium, 1-(1-hexyl)-3-methylimidazolium, 1-(1-hexyl)-3-
ethylimidazolium, 1-(1-hexyl)-
3-butylimidazolium, 1-(1-octy1)-3-methylimidazolium, 1-(1-octyI)-3-
ethylimidazolium, 1-(1-octyI)-
3-butylimidazolium, 1-(1-dodecy1)-3-methylimidazolium, 1-(1-dodecy1)-3-
ethylimidazolium, 1-(1-
dodecy1)-3-butylimidazolium, 1-(1-dodecy1)-3-octylimidazolium, 1-(1-
tetradecyI)-3-
methylimidazolium, 1-(1-tetradecyI)-3-ethylimidazolium, 1-(1-tetradecyI)-3-
butylimidazolium,
1-(1-tetradecyI)-3-octylimidazolium, 1-(1-hexadecyI)-3-methylimidazolium, 1-(1-
hexadecy1)-3-
ethylimidazolium, 1-(1-hexadecyI)-3-butylimidazolium, 1-(1-hexadecyI)-3-
octylimidazolium, 1,2-
dimethylimidazolium, 1,2,3-trimethylimidazolium, 1-ethyl-2,3-
dimethylimidazolium, 1-(1-buty1)-
2,3-dimethylimidazolium, 1-(1-hexyl)-2,3-dimethylimidazolium, 1-(1-octy1)-2,3-
dimethylimidazolium, 1,4-dimethylimidazolium, 1,3,4-trimethylimidazolium, 1,4-
dimethy1-3-
ethylimidazolium, 3-methylimidazolium, 3-ethylimidazolium, 3-n-
propylimidazolium, 3-n-
butylimidazolium, 1,4-dimethy1-3-octylimidazolium, 1,4,5-trimethylimidazolium,
1,3,4,5-
tetramethylimidazolium, 1,4,5-trimethy1-3-ethylimidazolium, 1,4,5-trimethy1-3-
butylimidazolium,
1,4,5-trimethy1-3-octylimidazolium, 1-prop-1-en-3-y1-3-methylimidazolium and 1-
prop-1-en-3-yl-
3-butylimidazolium. Specifically suitable imidazolium ions (1Ve) are 1,3-
diethylimidazolium,
1-ethy1-3-methylimidazolium, 1-(n-buty1)-3-methylimidazolium.
The anion of the ionic liquid is selected, for example, from
1) anions of the formulae: F-, Cl-, Br-, 1-, BF4-, PFs-, CF3503-,
(CF3S03)2N-, CF3CO2-,
CCI3CO2-, CN-, SCN-, OCN-.
2) anions of the formulae: S042-, HSO4-, S032-, H503-, RcOS03-, RcS03-.
3) anions of the formulae: P043-, HP042-, H2PO4-, RcP042-, HRcPO4-, RcRdPO4-
=
4) anions of the formulae: RcHP03-,RcRdP02-, RcRdP03-.
5) anions of the formulae: P033-, HP032-, H2P03-, RcP032-, RcHP03-, RcRdP03-
.
6) anions of the formulae: RcRdP02-, RcHP02-, RcIRdP0-, RcHP0-.
7) anions of the formula RcC00-.
8) anions of the formulae: B033-, HB032-, H2B03-, RcIRdB03-, RcHB03-,
RcB032-,
B(0172c)(0Rd)(0Re)(0Rf)-, B(HSO4)4-, B(RcSO4) 4-.
. PF 72809-2 CA 02856466 2014-05-21
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9) anions of the formulae: RcI3022-, RcRcB0-.
10) anions of the formulae: HCO3-, C032-, RcCO3-
11) anions of the formulae: S1044-, HSi043-, H2Si042-, H3S104-, RcSi043-,
RcRdSi042-,
RcRdReS104-, HRcSi042-, H2RcSiO4-, HRcRdS104-
12) anions of the formulae: RcSi033-, RcRdsio22-, RcRdResio-, RcRdResio3-,
RcRdResio2-,
RcRdSi032-.
13) anions of the formulae:
NC\
N
/, -
NC
10 00 0õ0
\\//
Pc RC¨S\ _ Rc¨S
\ _
_
N N N
i
d
Rd R ¨//S Rd
0 0 0 0
'
14) anions of the formulae:
SO2 -Rc
1 _
C
d
R6-0 S.Z \ SO -R
2
2
15) anions of the formula WO-.
16) anions of the formulae HS-, [Sv]2-, [HSv]-, [RCS]-, where v is a
positive integer from 2 to 10.
The RC, Rd, Re and I:21 radicals are preferably each independently
-hydrogen;
- unsubstituted or substituted alkyl, preferably unsubstituted or substituted
C1-C30-alkyl, more
preferably unsubstituted or substituted C1-C18-alkyl, which may be interrupted
by at least one
heteroatom or a heteroatom-containing group;
- unsubstituted or substituted aryl, preferably unsubstituted or substituted
C6-C14-aryl, more
preferably unsubstituted or substituted C6-C10-aryl;
- unsubstituted or substituted cycloalkyl, preferably unsubstituted or
substituted C5-C12-
cycloalkyl;
- unsubstituted or substituted heterocycloalkyl, preferably unsubstituted or
substituted
heterocycloalkyl having 5 or 6 ring atoms, where the ring, as well as carbon
ring atoms, has 1, 2
or 3 heteroatoms or heteroatom-containing groups;
- unsubstituted or substituted heteroaryl, preferably unsubstituted or
substituted heteroaryl
having 5 to 10 ring atoms, where the ring, as well as carbon ring atoms, has
1, 2 or 3
PF 72809-2 CA 02856466 2014-05-21
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heteroatoms or heteroatom-containing groups selected from oxygen, nitrogen,
sulfur and NRa;
where any two of these radicals in anions having a plurality of Rc to Rf
radicals, together with the
part of the anion to which they are bonded, may be at least one saturated,
unsaturated or
aromatic ring or a ring system having 1 to 12 carbon atoms, where the ring or
ring system may
have 1 to 5 nonadjacent heteroatoms or heteroatom-containing groups preferably
selected from
oxygen, nitrogen, sulfur and NRa, and where the ring or ring system is
unsubstituted or may be
substituted.
Preferred anions are Cl-, Br, formate, acetate, propionate, butyrate, lactate,
saccharinate,
carbonate, hydrogencarbonate, sulfate, sulfite, C1-C4-alkylsulfates,
methanesulfonate, tosylate,
trifluoroacetate, C1-C4-dialkylphosphates and hydrogensulfate.
Particularly preferred anions are Cl-, Br, HC00-, CH3C00-, CH3CH2C00-,
carbonate,
hydrogencarbonate, sulfate, sulfite, tosylate, CH3S03- or CH30S03
More particularly, the anions are selected from Cl- and CH3S03-.
Suitable ionic liquids for use in the process according to the invention are
commercially
available, for example, under the Basionic brand name from BASF SE.
Advantageous ionic liquids for use in the process according to the invention
are imidazolium
chlorides or imidazolium methanesulfonates or mixtures thereof.
Further advantageous ionic liquids for use in the process according to the
invention are, for
example, 1-ethyl-3-methylimidazolium chloride (EMIM Cl, Basionic ST 80), 1-
ethyl-3-
methylimidazolium methanesulfonate (EMIM CH3S03, Basionic ST 35), 1-butyl-3-
methylimidazolium chloride (BMIM Cl, Basionic ST 70), 1-buty1-3-
methylimidazolium
methanesulfonate (BMIM CH3S03, Basionic ST 78), methylimidazolium chloride
(HM1M Cl,
Basionic AC 75), methylimidazolium hydrogensulfate (HMIM HSO4 Basionic AC 39),
1-ethyl-3-
methylimidazolium hydrogensulfate (EMIM HSO4 Basionic AC 25), 1-buty1-3-
methylimidazolium
hydrogensulfate (BMIM HSO4 Basionic AC 28) 1-ethyl-3-methylimidazolium acetate
(EMIM
acetate, Basionic BC 01), 1-butyl-3-methylimidazolium acetate (BMIM acetate,
Basionic BC 02).
Particular preference is given to 1-ethyl-3-methylimidazolium chloride, 1-
butyl-3-
methylimidazolium chloride, methylimidazolium chloride, 1-ethy1-3-
methylimidazolium
methanesulfonate, 1-buty1-3-methylimidazolium methanesulfonate and mixtures
thereof.
Very particular preference is given to 1-ethyl-3-methylimidazolium chloride
(EMIM Cl, Basionic
ST 80), 1-butyl-3-methylimidazolium chloride (BMIM Cl, Basionic ST 70) and 1-
ethyl-3-
methylimidazolium methanesulfonate (EMIM CH3S03, Basionic ST 35).
The starting solution comprises, as well as the high boiler, at least one
further solvent. The
further solvent is especially water.This may also include mixtures of water
with hydrophilic
organic solvents having a boiling point less than 200 C (called low boilers)
in which the
saccharide used should preferably be soluble.
The further solvent is more preferably water. The starting solution is
therefore more preferably
an aqueous solution.
PF 72809-2 CA 02856466 2014-05-21
In a particular embodiment, the starting solution comprises exclusively water
and the high boiler
as solvents.
The starting solution comprises the high boiler, especially the polyether or
the ionic liquid,
5 preferably in amounts of 5 to 90% by weight, especially of 30 to 80% by
weight, more preferably
of 40 to 80% by weight, based on the total weight of the starting solution.
The water content of the starting solution is preferably less than 60% by
weight, especially less
than 50% by weight and more preferably less than 40% by weight, based on the
total weight of
10 the starting solution.
The starting solution preferably further comprises a catalyst. The catalyst
catalyzes the
conversion of the saccharide to HMF. Suitable catalysts are acids. Useful
acids include
heterogeneous acids which are dispersed in the starting solution, or
homogeneous acids which
are dissolved in the starting solution. Useful homogeneous acids include any
desired inorganic
or organic acids. Particular preference is given to using homogeneous protic
acids. Examples
include para-toluenesulfonic acid, methanesulfonic acid (Me0S03H), oxalic
acid, sulfuric acid,
hydrochloric acid or phosphoric acid.
If the high boiler used is an ionic liquid or DMSO, the use of a catalyst is
not absolutely
necessary, especially in the case of halide-containing ILs, for example EMIMCI
and BMIMCI.
However, the use of a catalyst accelerates the reaction and hence reduces the
residence time
in process step b). Thus, in the case of use of ionic liquids or DMSO as high
boilers, preference
is given to using a catalyst.
If a polyether, especially polyethylene glycol, is used as the high boiler,
the use of a catalyst is
absolutely necessary.
The starting solution comprises the acid preferably in amounts of 0.1 to 10
mol%, more
preferably of 0.1 to 5 mol% (based on the saccharide).
Preferred starting solutions comprise, for example,
1 to 40% by weight of saccharide
5 to 90% by weight of high boiler, preferably polyether or ionic liquid
1 to 50% by weight of water
0.1 to 10 mol% of acid (based on the saccharide)
0 to 10% by weight of other constituents, for example by-products from the
synthesis of the
saccharide,
based on the total weight of the solution.
PF 72809-2 CA 02856466 2014-05-21
11
Particularly preferred starting solutions comprise, for example,
to 30% by weight of saccharide
30 to 80% by weight of high boiler, preferably polyether or ionic liquid
5 10 to 50% by weight of water
0.1 to 5 mol% of acid (based on the saccharide)
0 to 5% by weight of other constituents, for example by-products from the
synthesis of the
saccharide,
based on the total weight of the solution.
The starting solution can be prepared here in various ways. In one embodiment,
the
components of the starting solution are supplied to a reaction vessel and
premixed therein. In
that case, this starting solution is supplied to process step b). In this
case, this starting solution,
in a particular embodiment, can also be preheated beforehand to a temperature
of 150-200 C.
In an alternative embodiment, the starting solution is prepared by the
following steps:
al) The saccharide and water are present in a reaction vessel.
a2) A further reaction vessel is initially charged with the high boiler and
preferably the catalyst.
a3) Immediately prior to process step b), the components are mixed,
preferably in a mixing
chamber.
In a further alternative embodiment, as well as the high boiler and preferably
the catalyst, a
metal chloride or metal nitrate may also be initially charged in process step
a2). Preference is
given to initially charging a metal chloride or metal nitrate when the
saccharide used in process
step al) is glucose or the saccharide used comprises glucose units, for
example sucrose.
"Immediately prior to process step b)" means that the period from commencement
of the mixing
time in process step a) until the entry of the mixture into the reaction
vessel, preferably an
evaporator, is at most 5 minutes, more preferably at most one minute.
In an alternative embodiment, the mixed starting solution can additionally be
partly vaporized by
an instantaneous pressure gradient (transition from standard pressure to a
vacuum by means of
a pressure regulator) and converted to the gas phase (called "flashing").
In a further alternative embodiment, the solutions of steps al and a2 in the
two reaction vessels
can be preheated to a temperature between 150 and 200 C, for example by means
of a heat
exchanger, separately from one another prior to the mixing.
In this case, the aqueous starting solution is already in a supercritical
state and may, in a further
alternative embodiment, be vaporized particularly efficiently by an
instantaneous pressure
PF 72809-2 CA 02856466 2014-05-21
12
gradient (transition from elevated pressure to a vacuum by means of a pressure
regulator) and
a relatively large proportion of water can be converted to the gas phase
(called "flashing").
In the case of high boilers which are solid or else very viscous at room
temperature, heating of
the reservoir vessels may be necessary in order that they are melted
beforehand and are
pumpable.
The above-described starting solution and the solvent having a boiling point
greater than 60 C
and less than 200 C (at standard pressure, called low boilers for short) are
supplied to a
reaction vessel.
= PF 72809-2 CA 02856466 2014-05-21
13
Process step b)
In process step b), the starting solution is converted to HMF in conjunction
with a distillation
which is known per se, in the presence of a solvent having a boiling point
greater than 60 C and
less than 200 C (at standard pressure, called low boiler for short). For this
purpose, the starting
solution is contacted with the low boiler in the reaction vessel.
Preferred low boilers are water vapor, alcohols, for example methanol,
ethanol, 2-butanol,
mono-, di- and polyethers, such as ethylene glycol dimethyl ether, diethylene
glycol monomethyl
ether, triethylene glycol, ketones such as 2-butanone or methyl isobutyl
ketone, esters such as
butyl acetate, and aromatics such as toluene or xylene. Preference is given to
polar protic low
boilers which enable a good interaction with HMF. The low boilers used are
more preferably
water vapor, methanol and 2-butanol. Very particular preference is given to
water vapor.
The treatment of the starting solution with the low boiler is effected
preferably under reduced
pressure, a useful pressure being especially from 10 to 200 mbar. The pressure
in the reaction
vessel is preferably 10 to 100 mbar, more preferably 20 to 80 mbar.
The treatment of the starting solution with the low boiler is effected
preferably at a temperature
of the starting solution of 100 to 250 C, more preferably of 140 to 250 C and
more preferably of
160 to 220 C and most preferably 170 to 220 C.
If the high boiler used is a polyethylene glycol, the starting solution is
treated with the low boiler
preferably at a temperature of 160 to 220 C.
If the high boiler used is an ionic liquid, the starting solution is treated
with the low boiler
preferably at a temperature of 180 to 220 C.
If the low boiler used is water vapor, the treatment of the starting solution
with water vapor is
effected preferably at a temperature of 140 to 220 C, more preferably at 160
to 220 C and most
preferably at 180 to 220 C. At these temperatures, the treatment can be
effected with an
industrially viable but minimal amount of water vapor. By increasing the
amount of water vapor,
the separating performance of the reactive distillation can be increased or
kept constant at the
same or a low temperature, but the use of an elevated amount of water vapor is
less preferred
for industrial reasons, since a high level of complexity is necessary to keep
the pressure
constant, a higher cooling performance on the distillate side is needed, and
the steam costs
rise.
In a further alternative embodiment, no low boiler is supplied to the reaction
vessel. In this
embodiment, the low boiler takes the form of water vapor in the reaction
vessel from the water
in the starting solution.
The process according to the invention is preferably operated continuously.
\
\
PF 72809-2 CA 02856466 2014-05-21
14
For this purpose, the starting solution and the low boiler are supplied
continuously to the
reaction vessel, and the product obtained, or distillate, is removed
continuously.
The volume flow rates depend on the size, the reactor performance and the
separation
performance of the reaction vessel selected.
In a preferred embodiment, the ratio of the amount of low boiler supplied to
the amount of the
starting solution supplied is within a range from 0.2 to 4 weight units of low
boiler to 1 weight
unit of starting solution, more preferably in the range from 0.3 to 2 weight
units of low boiler to
1 weight unit of starting solution, and especially 0.3 to 1.5 weight units of
low boiler to 1 weight
unit of starting solution.
Suitable reaction vessels are customary evaporators which are designed for the
supply of
starting solution and low boiler and especially for the above-described
continuous procedure.
The evaporator used is preferably an evaporator with short residence time in
the range of
seconds to minutes (2 seconds to 10 minutes). Advantageously, low thermal
stress on the
dehydration products formed is thus achieved. The residence time has a strong
influence on the
yield of HMF, since the distillation yield of HMF declines significantly as a
result of an increased
residence time in the event that conversion is already complete.
The residence time is therefore preferably 1 to 120 seconds, more preferably 1
to 60 seconds,
most preferably 5 to 30 seconds.
A suitable evaporator is in principle an apparatus customary for that purpose,
which in the
simplest case comprises a vessel or tubes with heatable walls as heat transfer
surfaces. The
evaporator may suitably be supplied with heat from the outside through the
walls, for example
with steam. The temperature in the evaporator is preferably within a range
from 100 to 300 C,
more preferably within a range from 150 C to 250 C. The pressure in the
evaporator is
preferably at most 100 mbar. The pressure in the evaporator is more preferably
within a range
from 10 mbar to 100 mbar, especially 10 mbar to 80 mbar.
In one embodiment, the evaporator used is a thin-film evaporator in which the
starting solution
in the evaporator is present as a liquid film.
Particular preference is given to vertical thin-film evaporators; such
vertical thin-film evaporators
are known by device names such as "Luwa" or especially "Sambay" from Buss or
Sulzer.
The thin-film evaporator can be used with or without a rotating wiper blade.
The preferred vertical thin-film evaporators are ultimately a vertical tube
with internal devices for
distribution and mixing of the starting solution, and external devices for
heating of the tube wall.
The starting solution is preferably supplied in the upper part of the thin-
film evaporator and
distributed as a film on to the heated pipe wall. The low boiler can be
supplied to the evaporator,
preferably to the thin-film evaporator, together with the starting solution or
at any other point in
the evaporator. The starting solution and the low boiler may be conducted
within the evaporator
in the same direction (cocurrent) or in opposite directions (countercurrent).
PF 72809-2 CA 02856466 2014-05-21
The low boiler is preferably conducted in countercurrent to the starting
solution. For this
purpose, the starting solution is supplied especially in the upper part of the
evaporator and the
steam in the lower part of the evaporator.
5 The low boiler and the volatile constituents of the starting solution are
preferably discharged via
a separator at the top of the evaporator and condensed (distillate).
The nonvolatile constituents pass through the evaporator and are removed as
liquid bottom
product.
10 Figure 1 (FIG 1) shows a corresponding apparatus composed of thin-film
evaporator (Sambay)
and device for condensation.
In an alternative embodiment, conversion and removal are accomplished using a
distillation
column, preferably a stripping column. The stripping column may consist of a
vertical tube with
15 external heating and a plurality of separation stages for the
establishment of the liquid/vapor
equilibrium. The feed is preferably to the top of the stripping column.
In a further alternative embodiment, a droplet separator (demister) is
arranged above the
distillation column. This prevents droplet entrainment (a sign of
nonestablishment of equilibrium
and simultaneously fluid-dynamic/flow-related overloading).
The starting solution is preferably supplied to the top of the distillation
column. The low boiler
can be supplied to the evaporator together with the starting solution or at
any other point in the
evaporator. The starting solution and the low boiler can be conducted within
the evaporator in
the same direction (cocurrent) or opposite directions (countercurrent).
The low boiler is preferably conducted in countercurrent to the starting
solution. For this
purpose, the starting solution is especially supplied in the upper part of the
evaporator and the
low boiler in the lower part of the evaporator.
The low boiler and the volatile constituents of the starting solution are
preferably discharged via
a separator at the top of the evaporator and condensed (distillate).
The nonvolatile constituents pass through the evaporator and are removed as
liquid bottom
product.
Figure 2 (FIG 2) shows a corresponding apparatus composed of distillation
column and device
for condensation with a simple feed.
Figure 3 (FIG 3) shows a corresponding apparatus composed of distillation
column and device
for condensation with separate heatable feeds and mixer.
The reaction in process step b) can, if desired, be performed such that only
partial conversion of
the saccharide to HMF or full conversion of the saccharide to HMF is effected.
In the case of
partial conversion, unconverted saccharide can be converted again; in the case
of full
PF 72809-2 CA 02856466 2014-05-21
16
conversion, there may be increased formation of by-products, especially what
are called
humins, i.e. oligomers of HMF.
Preferably at least 60%, especially at least 80% and, in a particular
embodiment, at least 90%
of the saccharide used is converted.
Process step c)
The distillate obtained is a dilute, HMF-comprising solution. The distillate
comprises the HMF
formed in the conversion and water, and the low boiler from the distillation.
The distillate
preferably comprises the HMF formed in the conversion and water from the
reaction and
distillation.
The distillate comprises especially more than 60%, especially more than 80%,
of the HMF
obtained overall in the conversion.
The distillate comprises especially at least 3% by weight of HMF, more
preferably at least 4% by
weight of HMF and most preferably at least 6% by weight of HMF, based on the
total weight of
the distillate.
In addition, the distillate may also comprise high boilers. In the case of use
of polyethers or ionic
liquids as high boilers, the distillate comprises only very small amounts of
high boilers, if any;
the content of polyethers or ionic liquids in the distillate is then
especially less than 5% by
weight, preferably less than 2% by weight and more preferably less than 1 or
less than 0.5% by
weight, based on the total weight of the distillate.
By-products which form in the conversion of the saccharide to HMF are
especially humins
(oligomers of HMF). The humins are obtained in the process according to the
invention
essentially not in the distillate but in the bottoms (see figure 1).
The distillate therefore comprises only very small amounts of humins, if any;
the content of
humins in the distillate is generally less than 2% by weight, especially less
than 0.5% by weight
and more preferably less than 0.1% by weight, based on the total weight of the
distillate. The
distillate is clear and has a pale yellow or orange color (according to the
HMF content).
In addition, the distillate comprises only small amounts of unconverted
saccharide, if any;
unconverted saccharide is present predominantly in the bottoms.
The content of unconverted saccharide in the distillate is generally less than
5% by weight,
especially less than 2% by weight and more preferably less than 1% by weight,
based on the
total weight of the distillate.
PF 72809-2 CA 02856466 2014-05-21
17
It is an advantage of the process according to the invention that by-products
of the HMF
synthesis, polyethers or ionic liquids as high boilers and unconverted
saccharide are obtained
essentially in the bottoms.
HMF is obtained in the preparation process according to the invention directly
as distillate with
high purity. The process according to the invention is therefore a simple and
effective process
for preparation of HMF and simultaneous removal of HMF from by-products and
unconverted
starting materials.
The distillate is suitable for chemical syntheses in which HMF is used as a
starting material.
More particularly, the distillate is suitable for chemical syntheses in which
the HMF starting
material is desired or required in high purity. An example given here is that
of the use of the
product solution for preparation of 2,5-furandicarboxylic acid or of 2,5-
bis(hydroxymethyl)furan.
Examples
Example 1: Batch experiments for HMF preparation in IL with variable water
content
The experiments were performed batchwise in a glass round-bottom flask with
reflux
condenser, mechanical stirrer and oil bath heating.
The starting solutions comprised: fructose (20 g), high boiler (100 g), p-
toluenesulfonic acid
(1 mol% based on fructose) and variable amounts of water.
The high boilers used were:
PEG-600: a polyethylene glycol having a molecular weight of 600
BMIMCI: 1-butyl-3-methylimidazolium chloride (BMIM Cl, Basionic ST 70)
Performance of the batch reactions:
All substances were initially charged in the round-bottom flask, heated
rapidly to 100 C and,
after attainment of the target temperature, the timing was started and samples
were taken from
the reaction vessel at regular intervals for reaction monitoring.
The composition was determined by means of HPLC.
The conversions of fructose reported are calculated from the residual amounts
of fructose in the
samples analyzed; fructose was converted to HMF and to by-products (humins).
The HMF yield
is the percentage of HMF formed based on the fructose content in the starting
solution.
PF 72809-2 CA 02856466 2014-05-21
=
18
Table 1: Batch experiments for HMF preparation in IL with variable water
content
Solvent Water content Time Conversion (%) Yield (%)
BMIMCI none <10 min 93% 84%
BMIMCI approx. 10% by wt. 1 h 98% 74%
BMIMCI approx. 20% by wt. 2 h 99% 74%
PEG-600 none 8 h 97% 43%
PEG-600 2% by weight 8 h (18 h) 94% (98%) 33% (43%)
Example 2: In situ dehydration of fructose and isolation of HMF by means of
steam distillation
Starting solution
The starting solutions were obtained by mixing pure substances.
The starting solutions comprised fructose, high boiler, acid and water (see
table).
The high boilers used were:
DMSO: dimethyl sulfoxide
PEG-600: a polyethylene glycol having a molecular weight of 600
Tetraglyme: tetraethylene glycol dimethyl ether
The acids used were:
H2SO4: sulfuric acid
p-TSA: para-toluenesulfonic acid
MSA: methanesulfonic acid
Oxalic acid
Performance of steam distillation
The steam distillation was performed in the apparatus according to figure 1.
The apparatus
consisted of a glass Sambay which is operated in countercurrent mode.
The starting solution was supplied at the top and flashed into vacuum by means
of a pressure
regulator, and the water vapor as the low boiler in the lower third.
The composition of the starting solution for various high boilers and the
selected temperatures
and pressures are listed in the table.
The temperature reported is that of the heating medium at the outer pipe wall,
which
corresponds in a good approximation to that of the liquid film of the starting
solution on the inner
pipe wall.
. PF 72809-2 CA 02856466 2014-05-21
,
19
The experiments were performed continuously; after each new temperature and
pressure
adjustment, attainment of a steady state was awaited.
The composition was determined by means of HPLC.
The reported conversions of fructose are calculated from the residual amounts
of fructose in the
bottoms and distillate; fructose was converted to HMF and to by-products
(humins). The
reported catalytic amounts of acid are based on fructose. The HMF yield is the
molar
percentage of the HMF in the distillate or in the bottoms, based on the
fructose content in the
starting solution.
HMF yield: m(HMF)/M/HMF) *100
m(Fru)/M (Fru)
-0
-n
Table 2: Continuous experiments for in situ dehydration of fructose and
isolation of HMF
N
CO
0
eP
High High Fructose Acid Amount
Temp- Press- Fructose [% by HMF Conversion .. HMF yield .. N
boiler boiler conc. of acid erature
ure wt.] in the [% by wt.] in the of fructose
Ickl
conc. [% by wt.] [mol%, [ C] [mbar] Distillate Bottoms
Distillate Bottoms [%] Distillate Bottoms
[% by based
wt.] on mol
of
fructose]
oxalic
P
tetraglyme 50 10 18 160 180 0.01 0.00
0.44 0.0 99.7 18.6 0.0 .
acid
rõ
N 3
0 g
DMS01 90 10 H2SO4 0.9 160 180 0.00 0.00
0.90 0.00 100.0 17.21 0.01 .
rõ
DMSO 90 10 H2SO4 0.01 110 380 0.00 5.43
0.05 2.94 72.1 1.0 21.6 '
,
,
PEG-600 49 24 MSA 0.6 160 25 0.17 5.73
1.73 0.22 80.9 19.1 1.0 u,
,
rõ
,
PEG-600 49 24 MSA 1.0 160 30 0.16 0.13
1.87 0.26 98.5 19.9 1.0
PEG-600 49 24 p-TSA 1.0 160 30 0.03 0.07
2.12 0.39 99.6 22.2 0
oxalic
PEG-600 49 24 1.0 160 30 0.17 12.72
0.40 0.31 65.7 4.0 1.2
acid
1 with DMSO as the added solvent, no bottoms were obtained at this temperature
with these pressure settings; the entire amount of HMF, DMSO and
water is in the distillate.
. PF 72809-2 CA 02856466 2014-05-21
,
21
Example 3: Isolation of HMF from HMF/high boiler solutions with different low
boilers
Starting solution
The starting solutions were obtained by mixing pure substances.
The starting solutions comprised HMF (10% by weight), fructose (10% by
weight), water (20%
by weight) and PEG-600 (60% by weight) based on the total weight of the
starting solution. No
conversion of fructose to HMF takes place in this solution since no acid has
been added.
The fructose was added only to show that it is distilled over into the
distillate only in a very small
proportion.
Performance of the distillation
The distillation was performed in the apparatus according to figure 1. The
apparatus consists of
a glass Sambay which is operated in countercurrent mode.
The starting solution was supplied at the top and flashed into vacuum by means
of a pressure
regulator, and the low boiler in the lower third. The low boiler is heated to
125 C by means of
electrical heating and decompressed by means of a pressure regulator and
introduced into the
distillation column.
The temperature specified is that of the heating medium at the outer pipe
wall, which
corresponds in a good approximation to that of the liquid film of the starting
solution at the inner
pipe wall.
The experiments were performed continuously; after each new temperature and
pressure
adjustment, attainment of a steady state was awaited.
The composition was determined by means of HPLC.
The HMF yield is the percentage of HMF in the distillate or in the bottoms,
based on the HMF
content in the starting solution.
The distillation separation performance is calculated from percentage of HMF
in the
distillate/percentage of HMF in the bottoms *100.
The fructose recovery is calculated from percentage of fructose in the
bottoms/percentage of
fructose in the starting solution *100 and is supposed to show that, under
these conditions,
fructose is not converted and is recovered for the most part in the bottoms.
CO
0
cig"
Table 3: Results of the isolation of HMF from HMF/high boiler solutions with
different low boilers
High Low boiler HMF yield (%) Fructose content
in the Distillation separation
boiler in the in the distillate (% by
wt.) performance
distillate bottoms
HMF distillate/bottoms
PEG-600 H20 82.3 7.6 0.06
91.5
PEG-600 no low boiler 12.1 82.7 0.12
12.8
PEG-600 2-BuOH 43.2 49.7 0.07
46.5
PEG-600 EGDME 29.5 53.9 0.09
35.4
PEG-600 MiBK 51.2 54.5 0.23
48.4
PEG-600 Bu-Ac 18.1 66.9 0.16
21.3 n)
v ;
PEG-600 toluene 31.6 57.78 0.15
35.4
' PF 72809-2 CA 02856466 2014-05-21
,
23
Example 4: In situ dehydration of fructose and isolation of HMF in a stripping
column
Starting solution
The starting solutions were obtained by mixing pure substances.
The starting solutions comprised fructose (20% by weight), high boiler (see
table), acid (1 mol%
based on fructose) and water (20% by weight), based on the total weight of the
starting solution.
The high boilers used were:
PEG-600: a polyethylene glycol having a molecular weight of 600
EMImCI: 1-ethyl-3-methylimidazolium chloride (EMIM Cl, Basionic ST 80)
The acid used was para-toluenesulfonic acid.
Performance of the reactive distillation
The reactive distillation was performed in the apparatus according to figure
2. The apparatus
consists of a two-part thermostatted glass Vigreux column with a reaction
section (below) and a
a demister (above the feed of the starting solution). The apparatus is
operated in countercurrent
mode and the starting solution is supplied via a single feed and flashed into
vacuum by means
of a pressure regulator.
The starting solution was supplied between demister and reaction section, and
the low boiler in
the lower third of the column.
The composition of the starting solution for various high boilers and the
temperatures and
pressures selected are listed in the table.
The temperature reported is that of the heating medium at the outer column
wall, which
corresponds in a good approximation to that of the liquid of the starting
solution at the inner
column wall.
The experiments were performed continuously; after each new temperature and
pressure
setting, attainment of a steady state was awaited.
The composition was determined by means of HPLC.
The reported conversions of fructose are calculated from the residual amounts
of fructose in the
bottoms and distillate; fructose was converted to HMF and to by-products
(humins). The
reported catalytic amounts of acid are based on fructose. The HMF yield is the
percentage of
HMF in the distillate or in the bottoms, based on the fructose content in the
starting solution.
PF 72809-2 CA 02856466 2014-05-21
,
,
24
The distillation separation performance is calculated from the percentage of
HMF in the
distillate/percentage of HMF in the bottoms *100
13
ll
V
f.)
Table 4: Continuous experiments for in situ dehydration of fructose and
isolation of HMF co
c.
CD
t%)
Entry High Starting Distillation Distillation Low Low Low
boiler / HMF conc. Fructose HMF conc. Fructose
boiler solution temp. pressure boiler boiler starting
in distillate conc. in in bottoms conc. in
flow rate ( C) (mbar) flow solution (% by
wt.) distillate (% by wt.) bottoms
(g/min) rate ratio
(% by wt.) (% by
(g/min) wt.)
1 EM1mC1 2.1 140 27 2.3 H20 1.1 0.72
0.00 0.67 19.10
2 EM1mCI 2.1 160 33 2.3 H20 1.1 1.53
0.00 1.61 0
3 EM1mCI 2.1 180 32 2.3 H20 1.1 2.88
0.00 4.09 4.09
P
4 EM1mCI 2.4 200 34 2.4 H20 1.0 6.05
0.00 2.95 0.00 .
rõ
EM1mCI 2.6 220 35 2.5 H20 1.0 8.10 0.00
1.14 0.00
CM ,72
6 EM1mCI 2.9 180 41 5.9 H20 2.0 1.53
0.00 1.06 4.72
rõ
7 EM1mCI 2.7 220 81 2.5 H20 0.9 8.33
0.00 1.94 0.00 ,
,
8 EM1mC1 2.8 220 35 1.5 2-butanol 0.6 7.72
0.00 4.13 0.00
,
rõ
,
9 EM1mCI 1.3 180 28 1.0 H20 1.0 4.35
0.00 5.52 2.26
EM1mCI 1.2 180 27 3.0 H20 2.5 2.79 0.00
1.56 0.87
11 EM1mCI 2.5 180 44 2.3 methanol 0.9 2.39
0.00 9.49 5.22
12 EM1mCI 2.6 220 45 2.3 methanol 0.9 7.80
0.00 1.80 0.13
PEG- H20
13 1.2 140 27 2.5 2.1 0.66
0.00 0.84 3.51
600
PEG- H20
14 1.1 160 27 2.6 2.3 1.54
0.00 0.89 0.83
600
PEG- H20
1.3 180 29 2.5 2.0 2.44 0.01 0.63
0.29
600
PF 72809-2
CA 02856466 2014-05-21
' 26
co cy
,-. o
O ci
coco
ci, O
,-. co
o o
ci O
IC) o
in (0
CV CV
co CV
CV CV
0 0
2
. r--
(NI (\i
-:rLc)
co cn
C o
o CV
04 CV
1¨ (N!
N-- e=-=
th 0 th 0
LU 0 LU 0
co N-
, ,
. PF 72809-2 CA 02856466 2014-05-21
,
27
Entry Overall HMF yield HMF yield Overall
Distillation
fructose in distillate in bottoms (%) HMF separation
conversion (%) select. performance for
(%) (%) HMF
dist./bottoms
1 17.8 5.5 4.1 53.9 57.1
_
2 100.0 12.1 8.8 20.9 57.8
3 86.1 25.3 19.9 52.5 56.0
4 100.0 50.6 13.4 64.1 79.1
100.0 62.6 5.5 68.1 92.0
6 67.8 16.8 10.3 40.0 62.0
7 100.0 62.9 11.7 74.6 84.3
8 100.0 51.3 16.1 67.4 76.1
9 92.8 36.0 24.9 65.6 59.1
94.5 46.9 14.0 64.4 77.1
11 82.6 19.4 45.0 78.0 30.1
12 99.7 58.1 6.8 65.1 89.5
13 81.5 10.1 6.3 20.2 61.7
14 96.3 25.9 5.7 32.8 81.9
98.8 38.2 3.4 42.1 91.8
16 99.2 44.0 0.8 45.2 98.2
17 99.6 42.6 0.2 42.9 99.6
Explanations:
5
Entries 1-5: Variation of temperature of 140 C-220 C with EMIMCI under
otherwise identical
conditions. The distillation separation performance remains constant at
approx. 50% up to
180 C and then rises rapidly up to 92% at 220 C. It is thus possible to show
clearly that the
process optimum is at 220 C in the case of !Ls such as EMIMCI.
Entries 3 & 6 and 9 & 10: Increase in the steam rate under otherwise identical
conditions.
Shows a slight improvement in distillation performance.
Entries 5 & 7: Variation of vacuum. In the case of poorer vacuum from 30 to 80
mbar, the
distillation performance falls by 8%.
Entries 5, 8, 12: Use of different low boilers. The same overall selectivity
of the reaction is
obtained with respect to HMF, but clear differences are found in distillation
performance in the
sequence of H20>Me0H>2-BuOH.
PF 72809-2 CA 02856466 2014-05-21
28
Entries 13-17: Use of PEG-600 at different temperatures. The optimum is at 200
C, where the
highest HMF selectivity is obtained with high distillation performance.
However, at the high
temperatures, slight entrainment of sugar into the distillate can be observed,
which does not
occur in the case of ILs.
Example 5: In situ dehydration of fructose and isolation of HMF in a stripping
column with
separate feeds
Starting solutions
The starting solutions were obtained by mixing pure substances.
Feed 1 is the saccharide solution and comprises fructose (40-70% by weight)
and water.
Feed 2 is the high boiler solution and comprises the high boiler (EMI MCI ¨
95% by weight),
para-toluenesulfonic acid (0.44% by weight) and water (4.5% by weight) based
on the total
weight of the starting solution.
Feed 3 is the low boiler (water, methanol ¨ Me0H or ethyl acetate - Et0Ac).
Performance of the reactive distillation
The reactive distillation was performed in the apparatus according to figure
3. The apparatus
consists of a two-part thermostatted glass Vigreux column with a reaction
section (below) and a
demister (above the feed of the starting solution). The apparatus is operated
in countercurrent
mode and the starting solution is obtained by mixing possibly preheated feed 1
and feed 2, and
is flashed into vacuum by means of a pressure regulator.
The starting solution was supplied between demister and reaction section, and
the low boiler in
the lower third of the column.
The temperature reported is that of the heating medium at the outer column
wall, which
corresponds in a good approximation to that of the liquid of the starting
solution at the inner
column wall.
The experiments were performed continuously; after each new temperature and
pressure
setting, attainment of a steady state was awaited.
The composition was determined by means of HPLC.
The reported conversions of fructose are calculated from the residual amounts
of fructose in the
bottoms and distillate; fructose was converted to HMF and to by-products
(humins). The
reported catalytic amounts of acid are based on fructose. The HMF yield is the
percentage of
HMF in the distillate or in the bottoms, based on the fructose content in the
starting solution.
. PF 72809-2 CA 02856466 2014-05-21
,
29
The distillation separation performance is calculated from the percentage of
HMF in the
distillate/percentage of HMF in the bottoms *100
Table 5: Continuous experiments for in situ dehydration of fructose and
isolation of HMF with
separate feeds
,
-o
m
-.I
r.)
co
Entry Fructose Preheater Feed 1 Feed 2 Amount Distillation
Distillation Feed 3 flow .. Low .. Ratio of feed
.. a
conc. in feed temp. flow flow of acid temp.
pressure rate (g/min) boiler 2/ feed 1 r..)
1 (% by wt.) ( C) rate rate (mol%) ( C) (mbar)
(g/min) (g/min)
1 40 180 1.3 1.2 0.9 200 17 2.4
, H20 0.9
2 40 180 1.3 1.1 0.8 220 25 2.4
H20 0.8
3 40 180 2.5 2.2 0.8 220 32 2.4
H20 0.9 _
4 70 180 1.5 1.1 0.7 220 27 2.4
H20 0.8 _
70 180 1.5 1 0.8 180 22 2.4 H20
0.9
.
_
6 40 25 2.5 2.3 0.8 220 18 2.4
H20 0.9 P
_
7 40 180 .1.3 1.4 1.0 220 35 1.9
Me0H 1.0
r.,
_ .
8 40 180 1.3 1.2 1.0 220 18 2.3
Et0Ac 1.0 co g
9a 40 180 1.3 1.4 1.0 220 28 2.4
H20 1.0
,
,
u,
'
Entry Ratio of HMF Fructose HMF Fructose Overall
HMF HMF Overall HMF Distillation separation
,
feed conc. in conc. in conc. in conc. in
fructose yield in yield in selectivity
performance for HMF
3/feeds distillate distillate bottoms bottoms conversion distillate bottoms
(%) -dist./bottoms
1 842 (% by wt.) (% by wt.) (% by wt.) (% by wt.) (%) (%)
(%)
1 0.9 7.23 0 1.67 0 100 65.9 5.9 71.8
91.8
2 1 7.21 _ 0 0.66 0 100 69.8 2.4 72.2
96.7
3 0.5 10.52 0 1.05 0 100 70.9 3.6 74.5
95.2
4 0.9 10.32 _ 0.00 _ 2.27 0.00 100.0 51.1 4.1
55.2 92.6
5 0.9 7.9 0.0 5.68 2.91 94.9 33.8 14.3 50.8
70.2
Entry Ratio of HMF Fructose HMF Fructose Overall HMF
HMF Overall HMF Distillation separation
-13
feed conc. in conc. in conc. in conc. in
fructose yield in yield in selectivity
performance for HMF 11
3/feeds distillate distillate bottoms bottoms conversion distillate bottoms
(%) -dist./bottoms
CO
a
18,2 (% by wt.) (% by wt.) (% by wt.) (% by wt.) (%) (%)
(%) co
6 0.5 7.41 0.00 3.88 0.62 98.2 42.8 16.1
60.0 72.6
7 0.7 6.58 0.00 1.01 0.00 100.0 58.5 4.3
60.6 93.0
8 0.9 17.89 0.00 1.76 0.00 100.0 54.1 6.8
60.9 88.8
9a 0.9 7.25 0.00 0.38 0.13 99.6 69.7 1.6
71.5 97.8
a in the high boiler solution, EMIM CH3S03 rather than EMIM Cl was used
a
a
a
,õ
PF 72809-2 CA 02856466 2014-05-21
32
Explanations:
Entries 1 & 2: The increase in the reaction/distillation temperature achieves
a better distillation
separation performance, with equal overall selectivity of the reaction.
Entries 2 & 3: A reduction in the amount of low boiler is economically and
industrially viable and,
for the same overall selectivity and distillation separation performance,
gives high HMF contents
in the distillate of approx. 10% by weight.
Entries 2 & 4: If a higher concentration of fructose in feed 1 is used, the
total water content in
the system falls and a poorer selectivity of the reaction is obtained because
the HMF formed
cannot be removed rapidly enough from the reaction medium.
Entries 4 & 5: A reduction in the reaction temperature to 180 C, even in the
case of high
fructose contents in feed 1, leads to a poorer distillation separation
performance and only to a
partial conversion of the fructose.
Entries 3 & 6: If feeds 1 & 2 are not heated, a poorer distillation separation
performance and a
lower overall selectivity of the reaction are found. This is probably because,
as a result of
heating of the aqueous saccharide solution, the water is already in a
supercritical state and, as
a result of the instantaneous decompression, vaporizes much better into the
vacuum and thus
entrains the HMF formed with it (better flash).
Entries 7 & 8: The low boilers used may also be methanol and ethyl acetate,
but slightly poorer
distillation separation performances and overall selectivities of the reaction
compared to water
are obtained. With ethyl acetate, a biphasic distillate is obtained, in which
the main proportion of
the HMF is in the aqueous phase (the yield reported is based on the overall
distillate).
Entry 9: The reaction can be performed with equal yields also with EMIM
CH3S03.
Example 8: In situ dehydration of glucose or glucose/fructose mixtures and
isolation of HMF in a
stripping column with separate feeds
Starting solutions
The starting solutions were obtained by mixing pure substances.
Feed 1 is the saccharide solution and comprises glucose (40% by weight) or
glucose/fructose
(ratio 58:42 ¨ 40% by weight total sugar) and water.
PF 72809-2 CA 02856466 2014-05-21
33
Feed 2 is the high boiler solution and comprises the high boiler (EMI MCI ¨
92.95% by weight),
CrCI3 (1.72% by weight), para-toluenesulfonic acid (0.42% by weight) and water
(4.91% by
weight), based on the total weight of the starting solution.
Feed 3 is the low boiler (water).
PF 72809-2
= CA 02856466 2014-05-21
34
Performance of the reactive distillation
The reactive distillation was performed in the apparatus according to figure
3. The apparatus
consists of a two-part thermostatted glass Vigreux column with a reaction
section (below) and a
demister (above the feed of the starting solution). The apparatus is operated
in countercurrent
mode and the starting solution is obtained by mixing possibly preheated feed 1
and feed 2, and
is flashed into vacuum by means of a pressure regulator.
The starting solution was supplied between demister and reaction section, and
the low boiler in
the lower third of the column.
The temperature reported is that of the heating medium at the outer column
wall, which
corresponds in a good approximation to that of the liquid of the starting
solution at the inner
column wall.
The experiments were performed continuously; after each new temperature and
pressure
setting, attainment of a steady state was awaited.
The composition was determined by means of HPLC.
The reported conversions of total sugar are calculated from the residual
amounts of glucose
and fructose in the bottoms and distillate; glucose and fructose were
converted to HMF and to
by-products (humins). The reported catalytic amounts of acid are based on
total sugar. The
HMF yield is the percentage of HMF in the distillate or in the bottoms, based
on the total sugar
content in the starting solution.
The distillation separation performance is calculated from the percentage of
HMF in the
distillate/percentage of HMF in the bottoms *100
-a
-n
Table 6: Continuous experiments for in situ dehydration of glucose or
glucose/fructose mixtures and isolation of HMF with separate feeds.
K3
00
0
13
Entry Feed Preheater Feed 1 flow Feed 2 Amount Distillation Distillation Feed
3 Low boiler rv
temp. rate (g/min) flow rate of acid temp. ( C) pressure
flow rate
( C) (g/min) (mol%) (mbar) (g/min)
-
1 glucose 180 1.3 1.3 0.8 220 27 2.4
H20
2 glucose 180 1.3 1.3 0.8 220 33 1.3
H20
3 glucose 180 1.3 1.2 0.8 180 37 2.2
H20
Glu/Fru
H20
4 180 1.3 1.3 0.8 220 37 2.3
(58:42)
Glu/Fru
H20
180 1.3 t 3 0.8 220 35 1.3
P
(58:42)
.
6a glucose 180 t 1.3 1.4 1.0 200 22 2.4
H20 co g
,
N)
,
Entry Ratio of Ratio of HMF Sugar HMF Sugar yield in Overall
sugar Overall HMF Overall Distillation .
,
0
feed feed yield in yield in yield in bottoms (%)
conversion select. HMF separation
,
2/feed 1 3/feeds distillate distillate bottoms (%)
(%) yield performance for
1&2 (%) (%) (%)
(%) HMF
dist./bottoms
1 0.9 _ 0.9 51.8 0.0 0.4 0.4 99.6
52.4 52.2 99.2
2 1.0 0.5 47.6 0.0 2.7 0.6 _ 99.4
50.6 50.3 94.4
3 0.9 0.9 19.7 Ø0 34.3 8.9 91.1
59.3 54.0 36.9
4 1.0 0.9 51.7 0.0 0.5 0.7 99.3
52.5 52.2 99.0
5 0.9 0.5 51.8 0.0 0.6 0.6 99.4
52.6 52.3 98.9
6a 1.0 0.9 54.2 0.6 2.9 0.4 99.0
57.6 57.1 -95.0
a in the high boiler solution, EMIM CH3S03 rather than EMIM Cl was used
. PF 72809-2 CA 02856466 2014-05-21
36
Explanation:
Entries 1 & 2: The reaction can also be performed with glucose and gives good
yields of HMF in
the distillate. Compared to fructose (table 4), the reaction with glucose is
somewhat less
selective and leads to an increased extent of unwanted side reactions if the
HMF formed cannot
be removed quickly enough from the reaction solution.
Entry 3: At a lower reaction temperature of 180 C, the selectivity for HMF
rises, but the
distillation separation performance falls at the same time.
Entries 4 & 5: The reaction with a mixture of glucose and fructose leads to
similarly good yields
of HMF to those with pure glucose.
Entry 6: The reaction can be performed with equal yields also with EMIM
CH3S03.
