Production of hybrid diesel fuel precursors from carbohydrates and petrochemicals using formic acid as a reactive solvent

Article abstract of DOI:10.1002/cssc.201200718

We report the one-pot alkylation of mesitylene with carbohydrate-derived 5-(hydroxymethyl)furfural (HMF) as a step toward diesel-range liquids. Using FeCl₃ as a catalyst, HMF is shown to alkylate toluene, xylene, and mesitylene in high yields in CH₂Cl₂ and MeNO₂ solvents. Efforts to extend this reaction to greener or safer solvents showed that most ether-based solvents are unsatisfactory. Acid catalysts (e.g, p-TsOH) also proved to be ineffective. Using formic acid as a reactive solvent, mesitylene could be alkylated to give mesitylmethylfurfural (MMF) starting from fructose with yields up to approximately 70 %. The reaction of fructose with formic acid in the absence of mesitylene gave rise to low yields of the formate ester of HMF, which indicates the stabilizing effect of replacing the hydroxyl substituent with mesityl. The arene also serves as a second phase into which the product is extracted. Even by using formic acid, the mesitylation of less expensive precursors such as glucose and cellulose proceeded only in modest yields (ca. 20 %). These simpler substrates were found to undergo mesitylation by using hydrogen chloride/formic acid via the intermediate chloromethylfurfural. Copyright

Full text of DOI:10.1002/cssc.201200718

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DOI: 10.1002/cssc.201200718
Production of Hybrid Diesel Fuel Precursors from
Carbohydrates and Petrochemicals Using Formic Acid as
a Reactive Solvent
Xiaoyuan Zhou and Thomas B. Rauchfuss*[a]
We report the one-pot alkylation of mesitylene with carbohy-
drate-derived 5-(hydroxymethyl)furfural (HMF) as a step toward
diesel-range liquids. Using FeCl3 as a catalyst, HMF is shown to
alkylate toluene, xylene, and mesitylene in high yields in
CH2Cl2 and MeNO2 solvents. Efforts to extend this reaction to
greener or safer solvents showed that most ether-based sol-
vents are unsatisfactory. Acid catalysts (e.g, p-TsOH) also
proved to be ineffective. Using formic acid as a reactive sol-
vent, mesitylene could be alkylated to give mesitylmethylfurfu-
ral (MMF) starting from fructose with yields up to approximate-
ly 70%. The reaction of fructose with formic acid in the ab-
sence of mesitylene gave rise to low yields of the formate
ester of HMF, which indicates the stabilizing effect of replacing
the hydroxyl substituent with mesityl. The arene also serves as
a second phase into which the product is extracted. Even by
using formic acid, the mesitylation of less expensive precursors
such as glucose and cellulose proceeded only in modest yields
(ca. 20%). These simpler substrates were found to undergo
mesitylation by using hydrogen chloride/formic acid via the in-
termediate chloromethylfurfural.
Introduction
The conversion of lignocellulosic biomass into liquid fuels has
attracted tremendous interest across the world.[1] The tradition-
al approach entails the conversion of cellulose, the most abun-
dant component of lignocellulosic biomass, to glucose, which
is enzymatically digested to ethanol, and CO2. The main alter-
native approach to such biofuels is purely chemical. It again
begins with the hydrolysis of cellulose to glucose, which is
subsequently isomerized and dehydrated into 5-(hydroxyme-
thyl)furfural (HMF), which retains all six carbon centers. HMF is
a platform compound as a precursor of diverse liquid fuels
such as 2,5-dimethylfuran (DMF),[2] g-valerolactone (GVL),[3] 2,5-
dimethyltetrahydrofuran (MTHF),[4] and 5-(alkoxymethyl)furfu-
rals.[5] HMF has also been discussed as a commodity chemical
as a precursor to furandicarboxylic acid, a potential replace-
ment for terephthalic acid.[6]
tives. CMF can be produced in good yields from glucose, cellu-
lose, or even raw biomass.[5a,9] Furthermore, our group has
shown that fructose can be converted to dimethylfuran (DMF)
via HMF as an intermediate by using formic acid as a hydrogen
donor and acid catalyst.[10]
This report focuses on HMF as a building block for the pro-
duction of precursors to diesel fuels. Petroleum-derived diesel
is a mixture of C11–C15 alkanes, cycloalkanes, and aromatic com-
pounds.[11] To convert lignocellulosic biomass, which is mainly
composed of C5–C6 carbohydrates, into diesel-range fuels, CÀC
bond formation is necessary. Several strategies have been re-
ported. Dumesic and co-workers used the aldol condensation
of furfurals with acetone or its derivatives to generate C9–C15
molecules, which were subjected to hydrodeoxygenation
(HDO) to generate linear alkanes.[12] Dumesic’s group has also
introduced an alternative approach starting from GVL, which
comes from biomass-derived carbohydrates via levulinic acid.
GVL undergoes decarboxylation over a silica/alumina catalyst
to produce butene and CO2. Butene is then oligomerized to
produce alkenes suitable for gasoline and/or jet fuel applica-
tions.[13] Recently, Corma and co-workers demonstrated that 2-
methylfuran, derived from hemicellulose, could be condensed
with itself or 5-methylfurfural under acidic conditions followed
by HDO to produce diesel-like 6-alkyl undecanes.[14] A similar
strategy was applied to the condensation reaction with furan
by Huber and co-workers.[12d]
The attractiveness of HMF as a building block has increased
with continuing advances in its production from carbohy-
drates. Systems that employ DMSO, N,N-dimethylacetamide
(DMA), biphasic mixtures, and ionic liquids as solvents have
been well studied.[7] Recently, Zhang and Lai showed that fruc-
tose could be efficiently converted to HMF by using isopropyl
alcohol as the solvent and HCl as the catalyst.[8] In addition to
HMF, another furanic product, chloromethylfurfural (CMF),
serves as a versatile precursor to various chlorine-free deriva-
[a] Dr. X. Zhou, Prof. T. B. Rauchfuss
Department of Chemistry
Related to the theme of converting C5 and C6 platform mole-
cules into diesel-range intermediates, we conceived a process
that involves Friedel–Crafts coupling between HMF and petro-
chemically derived arenes. We have previously shown that sev-
eral steps in the conversions of fructose can be conducted in
one pot[10] and we were attracted to the idea that similar pro-
University of Illinois at Urbana-Champaign
600 South Mathews Avenue, Urbana, IL 61801 (USA)
Fax: (+1)217-244-3186
E-mail: rauchfuz@illinois.edu
Supporting Information for this article is available on the WWW under
http://dx.doi.org/10.1002/cssc.201200718.
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generality of this method was demonstrated with different
arenes, including p-xylene and toluene. Under similar condi-
tions, these arenes gave rise to good yields of the coupled
products (Table 1, entries 5 and 6).
With the goal of converting sugars into MMF, we explored
potentially greener solvents that would dissolve sugars.
Neither MeNO2 nor CH2Cl2 are attractive solvents in the bio-
fuels area. Tests using THF, iPrOH, nBuOH, and H2O were unsuc-
cessful. The formation of MMF was not observed in any of
these solvents under the conditions used for MeNO2 or CH2Cl2
(Table 1, entries 7–10).
Scheme 1. Conversion of sugars to diesel-like compounds.
Arylation of HMF by using Brønsted acid catalysts
cess efficiencies could be realized in the Friedel–Crafts ap-
proach (Scheme 1).
The poor conversions of FeCl3-catalyzed reactions in oxygenat-
ed solvents is attributed to the basicity of the solvent, which
competes with HMF for the Lewis acid catalyst. A solution to
this problem was suggested by our finding that the Brønsted
acid p-toluenesulfonic acid (p-TsOH) could be used in place of
FeCl3 as the catalyst for the Friedel–Crafts reaction. Thus, MMF
was produced in good yields in both MeNO2 and CH2Cl2
(Table 2, entries 1 and 2). In oxygenated solvents, however, p-
Results and Discussion
Arylation of HMF by using an FeCl3 catalyst
Beller and co-workers briefly reported the FeCl3-catalyzed sol-
vent-free Friedel–Crafts reaction of HMF with o-xylene, which
provides a 37% yield of the coupled product.[15] Our studies
have focused on reactions with mesitylene, which was expect-
ed to generate only one isomer and will thus simplify product
analysis (Scheme 2). As shown in Table 1, the coupled product,
5-(mesitylmethyl)furfural (MMF), was obtained in high yields (>
90%) when the reaction was conducted in MeNO2. This con-
version was completed in 1 h, and longer reaction times had
little influence on the yield (Table 1, entries 1–3). Similar yields
were achieved when the solvent was switched to CH2Cl2. The
Table 2. p-TsOH-catalyzed arylation of HMF with mesitylene in various
solvents.[a]
Entry
Solvent
t
[h]
Yield[b]
[%]
1
2
3
4
5
6
MeNO2 (5 mL)
CH2Cl2 (5 mL)
iPrOH (5 mL)
THF (5 mL)
CH2Cl2 (5 mL)+H2O (5 mL)
MeNO2 (5 mL)+H2O (5 mL)
2
16
3
22
5
76
84
0
0
0
12
0
[a] Reaction conditions: HMF (1.0 mmol), mesitylene (5 mL), p-TsOH
(0.10 mmol), T=808C. [b] Yields were determined by using 1H NMR spec-
troscopy using MeNO2 as the integration standard.
TsOH is an ineffective catalyst (Table 2, entries 3 and 4).
Furthermore, the addition of H2O to the reactions with MeNO2
or CH2Cl2 inhibited the reaction (Table 2, entries 5 and 6).
Scheme 2. FeCl3-catalyzed arylation of HMF with mesitylene.
Table 1. Influence of solvent and arene on the FeCl3-catalyzed arylation
of HMF.[a]
Formic acid as a reactive solvent
Entry
Arene
Solvent
t
[h]
Yield
[%][b]
As the oxygenated solvents that are suitable for sugars inhibit
the Friedel–Crafts reaction, we tried the synthesis of MMF start-
ing from fructose in MeNO2. In the presence of HCl,[16] the
yields of MMF were modest (Table 3).
1
2
3
4
5
6
7
8
9
10
mesitylene
mesitylene
mesitylene
mesitylene
p-xylene
MeNO2
MeNO2
MeNO2
CH2Cl2
MeNO2
MeNO2
THF
iPrOH
nBuOH
H2O
1
6
94
92
96
92
95
87
0
0
0
0
20
12
2
The preceding results highlight problems with the low solu-
bility of fructose in MeNO2 and the ineffectiveness of conven-
tional acid catalysts. These considerations led us to explore the
use of formic acid (FA) as a reactive solvent. FA is an excellent
solvent for fructose, 0.9 gmLÀ1 of which dissolves in FA at
room temperature. FA is also a relatively strong acid with a pKa
of 3.77.[17] Initial experiments examined the FA-catalyzed alkyla-
tion of mesitylene with HMF. As summarized in Table 4, the re-
sults were promising although the yields are highly dependent
toluene
2
mesitylene
mesitylene
mesitylene
mesitylene
16
6
15
5
[a] Reaction conditions: HMF (1.0 mmol), arene (5 mL), FeCl3 (0.10 mmol),
solvent (5 mL), T=808C. [b] Yields were determined by using 1H NMR
spectroscopy using MeNO2 as the integration standard.
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Table 3. One-pot synthesis of MMF from fructose.[a]
Entry
Solvent
HCl
[mL]
T
[8C]
t
[h]
Yield[b]
[%]
1
2
3
4
MeNO2
MeNO2
–
20
20
20
0
80
120
120
120
48
4
4
0
23
22
17
MeNO2
4
[a] Reaction conditions: fructose (1.0 mmol), mesitylene (5 mL), FeCl3
(0.10 mmol), HCl (3.8m). [b] Yields were determined by using 1H NMR
spectroscopy using MeNO2 as the integration standard.
Table 4. One-pot synthesis of MMF in FA.[a]
Scheme 3. Pathway for the arylation of HMF to MMF in FA.
Entry
Substrate
HCl
[mL]
T
[8C]
t
[h]
Yield[b]
[%]]
ed the conversion, which, however, could be compensated for
by prolonged reaction times (Table 4, entries 13–15).
1
2
3[c]
4
5
6
7
8
HMF
HMF
HMF
HMF
HMF
FMF
fructose
fructose
fructose
fructose
fructose
fructose
fructose
fructose
fructose
0
0
0
0
0
0
0
0
80
80
80
6
22
4
2
4
4
5
12
2
4
33
66
55
79
94
90
36
53
72
68
66
58
62
63
72
120
120
120
120
120
120
120
150
150
100
100
100
Production of MMF from glucose and cellulose
We investigated the production of MMF from glucose and cel-
lulose in place of fructose. Such a process would require the
isomerization of glucose to fructose. As summarized in Table 5,
9
20
20
0
10
11
12
13
14
15
2
4
2
4
0
Table 5. One-pot synthesis of MMF in FA starting from glucose.[a]
20
20
20
Entry
CrCl3·6H2O
[mol%]
T
[8C]
t
[h]
Yield[b]
[%]
12
[a] Reaction conditions: substrate (1.0 mmol), FA (5 mL), mesitylene
(5 mL), HCl (3.8m). [b] Yield was determined by using H NMR spectrosco-
py using MeNO2 as the integration standard. [c] FeCl3 (0.1 mmol) was
added.
1
2
3
4
5
6
7
8[c]
0
5
120
120
120
120
100
150
120
120
4
4
4
4
4
4
12
5
10
11
20
23
4
19
22
52
1
10
20
10
10
10
0
on temperature, time, and additives. At 808C, up to a 66%
yield of MMF was achieved (Table 4, entries 1 and 2). The reac-
tion accelerated in the presence of FeCl3 (Table 4, entry 3).
Omitting FeCl3 but at 1208C, we generated MMF almost quan-
titatively after 4 h (Table 4, entries 4 and 5).
[a] Reaction conditions: glucose (1.0 mmol), FA (5 mL), mesitylene (5 mL),
HCl (3.8m, 20 mL). [b] Yield was determined by using 1H NMR spectrosco-
py using MeNO2 as the integration standard. [c] Reaction conditions: glu-
cose (0.39 mmol), FA (7 mL), mesitylene (15 mL), 1,2-dichloroethane
(15 mL), concentrated HCl (1 mL).
A plausible mechanism for the Friedel–Crafts arylation of
HMF is illustrated in Scheme 3. A control experiment showed
that FA solutions of HMF produced 5-(formyloxymethyl)furfural
(FMF) quantitatively in 10 min at 1208C. This result suggests
that the arylation of HMF proceeds via FMF. This pathway was
confirmed by the synthesis of MMF from FMF (Table 4, entry 6).
Encouraged by the effectiveness of FA as a reactive solvent,
we next examined the one-pot dehydration/arylation reaction
starting from fructose. Under conditions similar to those for
HMF but starting with fructose, MMF was formed in yields up
to 53% by using FA (Table 4, entries 7 and 8). These yields
exceed those discussed above if MeNO2/FeCl3 was employed
as the solvent in place of FA. Small amounts of HCl further ac-
celerate the conversion (Table 4, entries 9 and 10). In the ab-
sence of HCl, similarly good yields of MMF could be achieved
at elevated temperatures (Table 4, entries 11 and 12). A reduc-
tion of the reaction temperature from 120 to 1008C decelerat-
the reaction conditions that generate MMF from fructose in
good yields gave rise to only low yields from glucose (Table 5,
entry 1). This problem is attributed to the sluggish isomeriza-
tion of glucose to fructose. As chromium chlorides catalyze the
isomerization of glucose to fructose,[18] experiments were con-
ducted with CrCl3·6H2O, but the yield of MMF improved only
by 10% (Table 5, entries 2 and 3). A further increase of the cat-
alyst loading had a very limited effect on the yield of MMF
(Table 5, entry 4). This one-pot synthesis of MMF from glucose
is also significantly influenced by temperature. The reaction
conducted at 1008C resulted in a much lower yield than that
at 1208C (Table 5, entries 3 and 5), whereas a higher reaction
temperature (1508C) led to a negligible change in the yield of
MMF (Table 5, entry 6). Attempts to enhance the yield by ex-
tending the reaction time were unsatisfactory (Table 5, entry 7).
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A further objective was to convert cellulose directly to MMF.
The propose conversion would involve the initial depolymeri-
zation of cellulose followed by the conversion of glucose to
MMF via fructose and HMF. As anticipated from experiments
with glucose, only small amounts of MMF were produced from
cellulose (Table 6, entry 1). The poor conversions are attributed
to the slow depolymerization of cellulose. Indeed, the best
yields required a long reaction time (8 h) and a high tempera-
ture (1508C; Table 6, entries 2 and 3).
Scheme 5. Simplified synthesis of MMF from glucose and cellulose.
Experiments on the function of mesitylene
A common side-reaction that plagues the acid-catalyzed con-
version of fructose into HMF is the competing formation of in-
tractable polymers called humins.[19] In terms of their structure
and mechanism of formation, these dark, insoluble species are
poorly understood. Humins result from the polymerization/oli-
gomerization of furanic compounds;[20] it has been proposed
that they also arise through the condensation of sugars with
their dehydration products.[21] Experiments that involve fruc-
tose in the absence of mesitylene yield only small amounts of
FMF (Table 7, entry 1), even under conditions that otherwise
produce MMF in nearly 70% yield (Table 4, entry 10). Such ex-
periments produce large amounts of humins, which indicates
that the presence of mesitylene suppresses the formation of
humins.
Table 6. One-pot synthesis of MMF in FA starting from cellulose.[a]
Entry
T
t
Yield[b]
[%]
[8C]
[h]
1
2
3
4[c]
120
120
150
120
4
8
8
5
2
10
19
37
[a] Reaction conditions: cellulose (1.0 mmol, determined by moles of glu-
cose monomers contained in cellulose), FA (5 mL), mesitylene (5 mL), HCl
(3.8m, 20 mL), CrCl3·6H2O (0.1 mmol). [b] Yield was determined by using
1H NMR spectroscopy using MeNO2 as the integration standard. [c] Reac-
tion conditions: cellulose (0.39 mmol, determined by moles of glucose
monomers contained in cellulose), FA (7 mL), mesitylene (15 mL), 1,2-di-
chloroethane (15 mL), concentrated HCl (1 mL).
Table 7. Reactions of various substrates in FA in the absence of mesityle-
ne.[a]
Mascal and Nikitin reported that glucose and cellulose could
be converted into 5-(chloromethyl)furfural (CMF) with yields
up to 80% in a biphasic system by employing only aqueous
HCl as a reagent.[5a,9a] This method inspired us to produce MMF
from glucose and cellulose via CMF as the intermediate in
a two-pot procedure (Scheme 4). In one reactor, glucose and
cellulose were converted into a 1,2-dichloroethane solution of
CMF in one reactor, which was separated from the aqueous
phase and subsequently treated with FeCl3 and mesitylene in
a separate reactor. In this way, MMF was generated from glu-
cose and cellulose with yields of 68 and 36%, respectively.
Entry
Substrate
Yield[b]
[%]
Products
1
2
3
4[c]
5[c]
fructose
HMF
MMF
HMF+fructose
MMF+fructose
21
70
95
33
62
FMF
FMF
MMF
FMF
FMF (0.02 mmol)
MMF (0.60 mmol)
[a] Reaction conditions: substrate (1.0 mmol), FA (5 mL), HCl (3.8m,
20 mL), 1208C, 4 h. [b] Yield was determined by using H NMR spectrosco-
py using MeNO2 as the integration standard. [c] The substrate was a mix-
ture of HMF or MMF (0.66 mmol) and fructose (0.34 mmol).
1
We considered two possible beneficial roles for mesitylene
on the formation of furans from fructose. In the first hypothe-
sis, mesitylene removes the most reactive functional group
from HMF, the hydroxyl group. According to the second hy-
pothesis, as it is immiscible with FA, mesitylene functions as
a second phase to extract the products into a more benign en-
vironment. Related biphasic systems have been applied for the
in situ extraction of furfurals to minimize the formation of
humins in the dehydration process.[22] A series of experiments
were conducted to investigate the first hypothesis (Table 7).
In the absence of mesitylene, HMF led to the formation of FMF
in FA with a yield of 70%, and MMF was recycled quantitatively
under identical conditions (Table 7, entries 2 and 3). This result
is consistent with our hypothesis that the replacement of the
ÀOH group with an aryl group stabilizes the furanic compound
in FA and inhibits its condensation to produce humins. More-
Scheme 4. Generation of MMF from glucose and cellulose.
We further simplified the process in a one-pot reaction by
using concentrated HCl, 1,2-dichloroethane, FA, and mesitylene
(Scheme 5). This mixture consists of two liquid phases of which
the main components are H2O/HCl/FA and 1,2-dichloroethane/
mesitylene. By using this blend, MMF was produced from glu-
cose and cellulose with yields up to 52 (Table 5, entry 8) and
37% (Table 6, entry 4).
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over, as noted above, humins are also proposed to form from
the condensation of sugars with their dehydration products. To
understand the function of the aryl group in MMF and the for-
mation of humins in this system, the conversion of mixtures of
monosaccharides and furanic compounds were studied
(Table 7, entries 4 and 5). The addition of fructose to HMF re-
duced the yield of FMF to 33%, concomitant with a significant,
albeit qualitative, increased yield of humins. In contrast, MMF
was recycled quantitatively from an FA solution even in the
presence of fructose. Based on these results, we conclude that
humins mainly arise through the cross-polymerization of
sugars and their dehydration products. The homopolymeriza-
tion of HMF or FMF to form humins may also occur, but to
a much lesser extent. The conversion of HMF to MMF inhibits
the formation of humins from both of the pathways proposed
above.
Our major finding is that formic acid (FA) functions effective-
ly as both solvent and catalyst for the reactions of fructose,
glucose, and even cellulose. The dehydration of the sugar and
alkylation of the aromatic compound were combined in a one-
pot synthesis to give mesitylmethylfurfural (MMF) in yields of
20–70% under mild reaction conditions. Glucose and cellulose,
which are both more attractive and challenging substrates,
gave rise to only modest yields even with a CrCl3·6H2O/FA
system. A new biphasic system of concentrated HCl/FA and
1,2-dichloroethane/mesitylene substantially improved the
yields of MMF from glucose and cellulose. We propose that
this process involves chloromethylfurfural (CMF) as an inter-
mediate, which alkylates the mesitylene. As CMF can be ob-
tained in yields up to 80% from cellulose,[9] it is likely that the
yields of MMF from cellulose could be further optimized.
The new methodology minimizes the formation of humins,
which complicates conversions that involve polysaccharides.
This undesirable cross-polymerization reaction is inhibited by
the enhanced stability of MMF (vs. HMF) and the biphasic
nature of the reaction medium. Together with our previous
report,[10] these results further demonstrate the attractiveness
of formic acid in the processing of biomass.
In addition to the stabilizing effect of mesitylene, in this
case, this Friedel–Crafts arylation reagent may also serve as
a second phase solvent in which the products are more stable
than in FA with a catalytic amount of HCl. To probe this possi-
bility, the partition coefficients of HMF, FMF, and MMF in a mix-
ture of FA and mesitylene were determined (Table 8). HMF and
Table 8. Partition coefficients (P) of HMF, FMF, and MMF in FA/mesityle-
ne.[a]
Experimental Section
Entry
Substrate
P[b]
All reactions were performed without the exclusion of air. Unless
otherwise stated, starting materials and reagents were purchased
from Aldrich and used as received. Throughout this report, fructose
refers to d-(À)-fructose and glucose refers to d-glucose. FA (99%)
was purchased from Acros. NMR spectra were recorded by using
a Varian Unity 400 spectrometer. FTIR spectra were recorded by
using a Perkin–Elmer Spectrum 100 FTIR spectrometer. Chromato-
graphy was conducted with Siliaflash P60 from Silicycle (230–
1[c]
2
HMF
FMF
MMF
>19
>19
3
0.41
[a] Conditions: substrate (1.0 mmol), FA (5 mL), mesitylene (5 mL). [b] P=
[substrate]FA/[substrate]mesitylene. [c] The formation of FMF (16%) from HMF
was observed.
1
400 mesh). Yields were determined by H NMR spectroscopy with
MeNO2 as the integration standard unless otherwise indicated.
1H and 13C NMR chemical shifts are reported relative to SiMe4 and
were determined by reference to the residual 1H and 13C solvent
resonances. Coupling constants are given in Hz.
FMF are much more soluble in FA than in mesitylene, with
more than 95% of these solutes in the FA phase. In compari-
son, mesitylene is a better solvent than FA for MMF. These re-
sults suggest that the FA/mesitylene mixture is not an effective
biphasic system for the generation of HMF or FMF. However,
the solubilities of HMF (or FMF) could be modified dramatically
by substituting the hydroxyl (or formyl) group with an aryl
group, which makes them more soluble in the mesitylene
phase in which they are more stable.
Synthesis of MMF from HMF
A pressure reactor was charged with HMF (10.0 mmol, 1.26 g),
FeCl3 (1.0 mmol, 0.16 g), mesitylene (25 mL), and MeNO2 (25 mL).
The reaction mixture was stirred at 808C for 1 h. After cooling to
258C, the suspension was mixed with H2O (150 mL) and CH2Cl2
(100 mL). The aqueous phase was re-extracted with CH2Cl2 (2ꢁ
100 mL). The combined organic phases were dried over MgSO4, fil-
tered, and concentrated under vacuum. The residue was purified
by flash chromatography (10% Et2O/pentane) to give a yellow
Conclusions
This work describes an approach for the production of hybrid
fuels from readily available precursors derived from both bio-
logical sources and the benzene–toluene–xylene (BTX) stream
of petrochemicals.[23] The transformations examined involve
the Friedel–Crafts reactions of 5-(hydroxymethyl)furfural (HMF),
the principal intermediate obtained from the dehydration of
fructose. This sugar is obtained from glucose, which in turn is
the monomer in cellulose and amylose. Our alkylations were
optimized with mesitylene, although other arenes were also
shown to be suitable substrates.
1
solid. Yield: 1.80 g (79%); m.p. 58–608C; H NMR ([D6]acetone): d=
3
9.51 (s, 1H; ÀC(=O)H), 7.30 (d, JHH =4.0, 1H; furan ring protons),
3
6.88 (s, 2H; mesityl ring protons), 6.11 (d, JHH =4.0, 1H; furan ring
protons), 4.08 (s, 2H; ÀCH2À), 2.29 (s, 6H; o-CH3), 2.23 ppm (s, 3H;
p-CH3); 13C{1H} NMR ([D6]acetone): d=177.4, 162.2, 153.2, 137.5,
137.0, 131.0, 129.8, 124.1, 109.8, 28.9, 20.9, 20.1 ppm; GC–MS: m/z:
calcd for C15H16O2: 228.29; found: 228; elemental analysis calcd (%)
for C15H16O2: C 78.92, H 7.06; found: C 79.03, H 7.12.
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemSusChem 2013, 6, 383 – 388 387

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FULL PAPERS
www.chemsuschem.org
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1.18 g (52%).
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Acknowledgements
This research was supported by BP through the Energy Biosci-
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Received: September 24, 2012
Published online on December 23, 2012
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ChemSusChem 2013, 6, 383 – 388 388