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a
Table 2 Ru/C-catalysed hydrogenation of a-AL at atmospheric pressure
b
Yields
T
a-AL b
b-AL g-MBL VA
LA
g-VL
Entry [1C] t [h] conv. [%] [%]
[%]
[%] [%] [%]
c
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
80
60
40
r.t.
80
80
80
60
60
60
40
40
40
r.t.
r.t.
r.t.
6
6
6
6
67.7
38.8
25.9
21.6
7.3
4.2
1.6
1.0
4.8
0.9
1.0
1.8
1.8
0.4
1.6
0.1
0.1
0.5
0.3
0.0
1.8
1.8
2.5
2.5
1.7
0.5
0.1
1.6
0.9
0.3
0.4
0.3
0.2
1.1
0.8
0.0
0.6
0.2
0.2
0.1
0.2
0.9
1.5
0.2
0.5
2.1
0.9
0.9
0.5
0.8
1.6
4.1
0.5
0.9
56.0
c
31.8
20.8
17.4
44.6
80.3
92.9
19.2
49.7
c
c
d
d
d
d
d
1.5 52.2
84.2
4.5 99.6
23.3
4.5 53.8
Scheme 3 Synthesis of 2-MTHF from LA and a-AL.
3
3
In conclusion, we were able to demonstrate the conversion
d
d
d
d
d
d
d
0
1
2
3
4
5
6
6
6
16
20
16
20
24
83.3
76.2
93.3
97.6
63.6
83.3
99.0
0.9 1.4 80.4 of a-AL into g-VL over Ru/C in a batch or open reactor setup.
0.9
1.0
1.1
2.5
1.9
2.0
70.9
89.9
94.1
The reaction conditions were optimized in both cases and full
conversion of a-AL with almost full selectivity toward g-VL was
0.4 1.1 60.5 obtained under solvent-free conditions at room temperature
0.7
0.9
1.5
1.8
80.1
96.4
and atmospheric pressure. Several side reactions were identi-
fied and a reaction network was proposed. For the first time,
VA was obtained under very mild conditions through hydro-
genation of a-AL over Ru/C as a catalyst. Finally it was demon-
strated that the use of a-AL as starting material is beneficial for
the one-pot conversion to 2-MTHF.
This work was supported by the Robert Bosch Foundation in
the frame of the Robert Bosch Junior Professorship for the
efficient utilization of renewable resources. This work was
performed as part of the Cluster of Excellence ‘‘Tailor-Made
Fuels from Biomass’’ funded by the Excellence Initiative by the
German federal and state governments to promote science and
research at German universities.
a
b
Conditions: a-AL (8.44 g, 86.03 mmol); Ru (5%)/C (500 mg, 245 mmol Ru).
c
À1
d
Determined by GC.
00 mL min
H
2
-flow rate of 130 mL min
.
2
H -flow rate of
À1
5
.
studies aimed at elucidating the origin of the ring-opening
reactivity are currently being conducted. By increasing the
hydrogen flow rate from 130 to 500 mL min the conversions
À1
increased considerably. At 80 1C, full conversion of a-AL with
93% yield of g-VL is reached after 4.5 h (Table 2, entries 5 to 7);
however, a significant portion (up to 20%) of the mixture is lost
due to increased hydrogen flow. At lower temperatures, the loss
decreases to less than 5%.
Considering an application on the industrial scale, recycling
of gas and liquid would be introduced to minimize losses.
Upon lowering the temperature from 80 to 40 1C, the time to
attain nearly full conversion is increased from 4.5 to 20 h
Notes and references
1 V. Vandermeulen, M. Van der Steen, C. V. Stevens and G. Van
Huylenbroeck, Biofuels, Bioprod. Biorefin., 2012, 6, 453–464.
BP Energy Outlook 2035, January 2014.
G. A. Olah, G. K. S. Prakash and A. Goeppert, J. Am. Chem. Soc., 2011,
133, 12881–12898.
2
3
(Table 2, entries 5–13). Interestingly, at r.t., full conversion with
96% g-VL was reached after 24 h (Table 2, entries 14–16). These
4
5
A. M. Ruppert, K. Weinberg and R. Palkovits, Angew. Chem., Int. Ed.,
data again show that the reaction proceeds efficiently and
selectively under very mild conditions. Therefore it is expected
that this reaction has high potential for industrial applications
and can be considered as a better candidate than LA hydro-
genation since energy intense water separation is avoided and a
broad operation window is provided.
2012, 51, 2564–2601.
T. Werpy and G. Petersen, Top Value Added Chemicals from Biomass.
Volume I – Results of Screening for Potential Candidates from Sugars and
Synthesis Gas, Report No. NREL/TP-510-35523, National Renewable
Energy Laboratory, Golden, CO, 2004, http://www.osti.gov/bridge.
L. E. Manzer, Appl. Catal., A, 2004, 272, 249–256.
6
7 D. C. Elliott and J. G. Frye, US. Pat., 5883266A, Battelle Memorial
Institute, USA, 1999.
As mentioned above, we previously proposed that the poor
formation of 2-MTHF in a one-pot reaction starting from LA
was due to a prohibitive effect of water on the reaction. This has
motivated us to use a-AL as a substrate, which leads to inter-
8
J. C. Serrano-Ruiz, D. Wang and J. A. Dumesic, Green Chem., 2010,
2, 574–577.
9 M. G. Al-Shaal, W. R. H. Wright and R. Palkovits, Green Chem., 2012,
4, 1260–1263.
1
1
1
1
0 W. R. H. Wright and R. Palkovits, ChemSusChem, 2012, 5, 1657–1667.
1 O. A. Abdelrahman, A. Heyden and J. Q. Bond, ACS Catal., 2014, 4,
1171–1181.
7
,22
mediate formation of neat g-VL (Scheme 3).
Using a fresh
batch of commercial Ru/C, the reaction of LA was tested again,
resulting in full conversion with only 10% yield of 2-MTHF with
1
1
1
1
2 B. V. Timokhin, V. A. Baransky and G. D. Eliseeva, Russ. Chem. Rev.,
1999, 68, 73–84.
2-butanol and 2-pentanol as main by-products. Applying the
3 R. A. Amos and J. A. Katzenellenbogen, J. Org. Chem., 1978, 43,
560–564.
4 J. H. Helberger, S. Ulubay and H. Civelekoglu, Liebigs Ann. Chem.,
same conditions for a-AL results in full conversion with 25%
selectivity toward 2-MTHF. Besides this 21% g-VL, 15% 2-butanol
and 14% 2-pentanol were observed (Scheme 3). These results
show that use of a-AL instead of LA has a positive effect on
1949, 561, 215–220.
5 M. Mascal, S. Dutta and I. Gandarias, Angew. Chem., Int. Ed., 2014,
53, 1854–1857.
7
,16
16 L. E. Manzer, US. Pat., 0171374A1, E. I. Du Pont De Nemours and
the selectivity towards 2-MTHF.
Further studies aimed at
Company, 2005.
the selective synthesis of fuel precursors are currently being
conducted.
1
7 R. H. Leonard, US. Pat., 2809203, Heyden Newport Chemical
Corporation, USA, 1957.
10208 | Chem. Commun., 2014, 50, 10206--10209
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