Please do not adjust margins
Green Chemistry
Page 4 of 6
DOI: 10.1039/C7GC00580F
COMMUNICATION
Journal Name
competing experiment (Table 1, entry 12). It could further be deduced
that the evolution of H2 from PMHS caused by the reduction of Pd(II) to
Pd(0) might be responsible for the formation of the byproducts DTHF
and DH (Scheme S1).
hydrosilylation reaction, inert for the carbonyl groups of aliphatic
compounds while favorable for in situ dehydration of sugars, exclusively
acted on the deoxygenation of furanic intermediates to DMF via a
hydride transfer process facilitated by an alcoholic solvent. This new
and simple catalytic process shows great potential to be performed in a
batch mode or a fixed-bed continuous reactor, rendering the possibility
of good product quality and high-volume production with a lower unit
cost but time and energy savings, which can be used as a reference for
developing intensified production systems for complex reactions.
Acknowledgements
The work is financially supported by the National Natural Science
Foundation of China (21576059, 21666008), Key Technologies R&D
Program of China (2014BAD23B01), Postdoctoral Science Foundation of
China (2016M600422), and Jiangsu Postdoctoral Research Funding Plan
(1601029A). SS thanks the Department of Biotechnology (Government
of India), New Delhi, India.
Figure 4. Reuse of Pd/C-SO3H-TMS for producing DMF directly from fructose (Reaction
conditions: 5 wt% fructose, 2 mol% Pd/C-SO3H-TMS, 2.5 mmol PMHS (9 equiv. H-), 1.5
mL n-butanol, 120 ºC, and 2 h)
To explicitly elucidate the reaction mechanism of Pd-catalyzed
1
deoxygenation of HMF formed in situ from hexoses, H NMR spectrum
Notes and references
of fructose-to-DMF conversion in methanol-d4 under identical
conditions was recorded (Figure S12). However, the integral area of
methyl protons in DMF was found to be 1.8 times higher than that of H
in the furan ring, which should normally be 3-fold, indicating that the
deuterium (D) incorporation from CD3OD occurred via a facile H/D
exchange with the surface-generated Pd-H species. This speculation can
be substantiated by the presence of three varied m/z values of DMF
(i.e., MS, MS+1 and MS+2), as shown in GC-MS spectrum (Figure S13 A).
Intriguingly, no H/D exchange was observed (Figure S13 B-C), when
chloroform-d3 was used as solvent although the yield of DMF was
relatively low (<10%). Using MFF as starting substrate and
diphenylsilane-d2 as H-donor, the hydrogenation/deoxygenation of MFF
in chloroform-d3 could exclusively give MFA and DMF with 1 and 2 more
m/z (Figure S14), respectively, demonstrating that both hydrogenation
and deoxygenation processes were proceeded via hydrosilylation by
separately offering hydride species to aldehyde and alcoholic groups of
furanics. Moreover, a trace of 2,5-diformylfuran from the oxidation of in
situ formed HMF was observed during reactions (Figure S15), suggesting
the possibility in oxidative addition of Pd(0) to hydroxymethyl group.
On the basis of above discussions, the plausible reaction pathways
for producing DMF from sugars can be envisaged to proceed via the
following steps (Scheme S2): (1) HMF is first generated via acid-
catalyzed hydrolysis/dehydration of sugar (Reac. A), wherein Pd does
not play a role in the hydrogenation of the sugar to hexitols; (2)
Oxidative addition of Pd(0) to the hydroxyl group of HMF takes place
(Reac. B), followed by dehydration (Reac. C) and hydride transfer (Reac.
D) to give MFF, which can be supported by the absence of DHMF and
DHMTF while the formation of carbocation intermediates during the
1. a) N. T. S. Phan, C. S. Gill, J. V. Nguyen, Z. J. Zhang, C. W. Jones, Angew.
Chem. Int. Ed. 2006, 45, 2209-2212; b) C. C. Wang, J. C. Lee, S. Y. Luo, S. S.
Kulkarni, Y. W. Huang, C. C. Lee, K. L. Chang, S. C. Hung, Nature 2007, 446,
896-899; c) M. L. McKee, P. J. Milnes, J. Bath, E. Stulz, R. K. O’Reilly, A. J.
Turberfield, J. Am. Chem. Soc. 2012, 134, 1446-1449; d) M. J. Climent, A.
Corma, S. Iborra, L. Martí, ChemSusChem 2014, 7, 1177-1185.
2. a) R. Rinaldi, F. Schüth, Energy Environ. Sci. 2009, 2, 610-626; b) T. Sehl, H.
C. Hailes, J. M. Ward, R. Wardenga, E. von Lieres, H. Offermann, R.
Westphal, M. Pohl, D. Rother, Angew. Chem. Int. Ed. 2013, 52, 6772-6775;
c) M. Pintado-Sierra, A. M. Rasero-Almansa, A. Corma, M. Iglesias, F.
Sánchez, J. Catal. 2013, 299, 137-145; (d) H. Li, Z. Fang, R. L. Smith Jr., S.
Yang, Prog. Energ. Combust. 2016, 55, 98-194.
3. a) L. D. Schmidt, P. J. Dauenhauer, Nature 2007, 447, 914-915; b) D. M.
Alonso, J. Q. Bond, J. A. Dumesic, Green Chem. 2010, 12, 1493-1513; c) M.
J. Climent, A. Corma, S. Iborra, Green Chem. 2011, 13, 520-540; d) A. M.
Ruppert, K. Weinberg, R. Palkovits, Angew. Chem. Int. Ed. 2012, 51, 2564-
2601; e) V. Choudhary, S. H. Mushrif, C. Ho, A. Anderko, V. Nikolakis, N. S.
Marinkovic, A. I. Frenkel, S. I. Sandler, D. G. Vlachos, J. Am. Chem. Soc.
2013, 135, 3997-4006; f) M. Besson, P. Gallezot, C. Pinel, Chem. Rev. 2014,
114, 1827-1870.
4. a) O. O. James, S. Maity, L. A. Usman, K. O. Ajanaku, O. O Ajani, T. O.
Siyanbola, S. Sahu, R. Chaubey, Energy Environ. Sci. 2010, 3, 1833-1850; b)
B. Liu, Z. Zhang, ChemSusChem 2016, 9, 2015-2036; c) H. Li, J. He, A.
Riisager, S. Saravanamurugan, B. Song, S. Yang, ACS Catal. 2016, 6, 7722-
7727.
5. a) G. H. Wang, J. Hilgert, F. H. Richter, F. Wang, H. J. Bongard, B. Spliethoff,
C. Weidenthaler, F. Schüth, Nature Mater. 2014, 13, 293-300; b) B. Saha,
C. M. Bohn, M. M. Abu-Omar, ChemSusChem 2014, 7, 3095-3101; c) Y. Liu,
M. A. Mellmer, D. M. Alonso, J. A. Dumesic, ChemSusChem 2015, 8, 3983-
3986; d) A. J. Kumalaputri, G. Bottari, P. M. Erne, H. J. Heeres, K. Barta,
ChemSusChem 2014, 7, 2266-2275; e) Y. Zu, P. Yang, J. Wang, X. Liu, J. Ren,
G. Lu, Y. Wang, Appl. Catal. B: Environ. 2014, 146, 244-248; f) A. S.
Nagpure, N. Lucas, S. V. Chilukuri, ACS Sustainable Chem. Eng. 2015, 3,
2909-2916; g) J. Gmeiner, M. Seibicke, S. Behrens, B. Spliethoff, O. Trapp,
ChemSusChem 2016, 9, 583-587; h) A. B. Gawade, M. S. Tiwari, G. D.
Yadav, ACS Sustainable Chem. Eng. 2016, 4, 4113-4123; i) J. Luo, H. Yun, A.
V. Mironenko, K. Goulas, J. D. Lee, M. Monai, C. Wang, V. Vorotnikov, C. B.
Murray, D. G. Vlachos, P. Fornasiero, R. J. Gorte, ACS Catal. 2016, 6, 4095-
4104; j) M. Y. Chen, C. B. Chen, B. Zada, Y. Fu, Green Chem. 2016, 18,
reaction is not ruled out because of etherified products (Figure S16)18
;
(3) Pd(0)-catalyzed hydrosilylation of the aldehyde group of MFF occurs
(Reac. E), and then DMF is obtained via repeating Reac. C-D while a
small amount of MFA can be formed through reverse Reac. B.
Conclusions
In conclusion, the chemocatalytic production of DMF with almost
quantitative yields directly from different hexose sugars could be
achieved over a highly recyclable modified Pd/C catalyst under mild
conditions. A scale-up procedure catalyzed by 0.04 mol% Pd/C-SO3H-
TMS was also able to produce DMF in a good yield of 85%. Further,
kinetic and deuterium-labeling studies demonstrated that the
4 | Green Chem., 2017, 00, 1-5
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins