Paper
Green Chemistry
DOSY-NMR of the lignins (ESI Fig. S3†) showed that in DMSO- Anna Bosch Rico for providing the propionaldehyde stabilized
d6, a solvent that forms strong hydrogen bonds with phenolic lignin and Yann Lavanchy for performing the GPC analysis.
molecules and thus disfavours intermolecular interactions
between lignin and phenol,32 all phenolated lignins showed a
unique diffusion behaviour in solution, suggesting that
phenol was covalently bound to the polymeric scaffold and not
References
just interacting with it physically.
1 F. G. Calvo-Flores and J. A. Dobado, ChemSusChem, 2010, 3,
1227–1235.
2 S. Kalami, N. Chen, H. Borazjani and M. Nejad, Ind. Crops
Prod., 2018, 125, 520–528.
3 M. Lettner, F. Hesser, B. Hedeler, P. Schwarzbauer and
T. Stern, J. Cleaner Prod., 2020, 256, 120520.
4 J. Li, J. Zhang, S. Zhang, Q. Gao, J. Li and W. Zhang,
Polymers, 2017, 9, 428.
5 J. Ralph, C. Lapierre and W. Boerjan, Curr. Opin.
Biotechnol., 2019, 56, 240–249.
6 X. Wu, X. Fan, S. Xie, J. Lin, J. Cheng, Q. Zhang, L. Chen
and Y. Wang, Nat. Catal., 2018, 1, 772–780.
7 A. E. Kazzaz and P. Fatehi, Ind. Crops Prod., 2020, 154,
112732.
8 A. Tribot, G. Amer, M. Abdou Alio, H. de Baynast,
C. Delattre, A. Pons, J.-D. Mathias, J.-M. Callois, C. Vial,
P. Michaud and C.-G. Dussap, Eur. Polym. J., 2019, 112,
228–240.
9 R. El Hage, N. Brosse, P. Sannigrahi and A. Ragauskas,
Polym. Degrad. Stab., 2010, 95, 997–1003.
10 F. S. Chakar and A. J. Ragauskas, Ind. Crops Prod., 2004, 20,
131–141.
11 L. Shuai, M. Talebi Amiri and J. S. Luterbacher, Curr. Opin.
Green Sustainable Chem., 2016, 2, 59–63.
12 M. Ghorbani, F. Liebner, H. W. G. van Herwijnen,
L. Pfungen, M. Krahofer, E. Budjav and J. Konnerth,
BioResources, 2016, 11, 6727–6741.
13 M. Wang, M. Leitch and C. Xu, Eur. Polym. J., 2009, 45,
3380–3388.
14 S. Bertella and J. S. Luterbacher, Trends Chem., 2020, 2,
440–453.
15 F. Taleb, M. Ammar, M. ben Mosbah, R. ben Salem and
Y. Moussaoui, Sci. Rep., 2020, 10, 11048.
16 M. Zhou, H. Shi, C. Li, X. Sheng, Y. Sun, M. Hou, M. Niu
and X. Pan, Ind. Eng. Chem. Res., 2020, 59, 14296–14305.
17 J. Podschun, B. Saake and R. Lehnen, Eur. Polym. J., 2015,
67, 1–11.
Conclusions
We demonstrated that the aldehyde stabilization process pre-
viously used to maximize the production of monomers from
lignin is also an effective tool for the controlled and simul-
taneous extraction and chemical modification of lignin.
Furthermore, this process allows us to introduce functional
groups on the lignin scaffold that were not originally present
on the biopolymer and that could then be further modified.
We notably demonstrated that this method offers the unique
possibility to functionalize lignin with free aldehyde groups.
This aldehyde functionalization could be used to strongly
increase the reactivity of lignin towards phenolation in both
acid and base-catalysed systems. The use of any fossil-based
phenol as a solvent for phenolation reactions creates health
and sustainability drawbacks. However, efforts are being made
in order to minimize the impact of phenol by either sourcing
the molecule from biobased feedstocks33 or by developing
resins where the phenolic part of said polymers are substituted
by more sustainable and bio-based alternatives.34–36 The
increased reactivity of TALD-lignin in phenolation resins
suggests that this kind of functionalization could be beneficial
for the subsequent integration of a higher fraction of lignin
into phenolic resins, which would not eliminate the use of
fossil-based phenol but at least contribute to reducing its use.
Because aldehydes are versatile chemical functionalities that
can react under mild conditions to obtain a variety of other
important functional groups such as amines, carboxylic acids
and hydroxy groups, we believe that this work could expand
lignin functionalization possibilities, and ultimately enable
substituting fossil-based materials with renewable alternatives.
Conflicts of interest
18 L. Shuai, M. T. Amiri, Y. M. Questell-Santiago, F. Héroguel,
Y. Li, H. Kim, R. Meilan, C. Chapple, J. Ralph and
J. S. Luterbacher, Science, 2016, 354, 329–333.
19 W. Lan, M. T. Amiri, C. M. Hunston and J. S. Luterbacher,
Angew. Chem., Int. Ed., 2018, 57, 1356–1360.
20 G. R. Dick, S. Bertella and J. S. Luterbacher, Production of
fragments of lignin with functional groups, EP19202957,
2019.
SB and JSL are inventors on a European patent application
(EP19202957) that was submitted by EPFL and covers the iso-
lation of functionalized lignins via the aldehyde assisted
process. JSL is co-founder and part owner of Bloom
Biorenewables Ltd that aims at commercializing the aldehyde
assisted fractionation process.
21 C. L. Perrin and K.-L. Chang, J. Org. Chem., 2016, 81, 5631–5635.
22 K. A. Goulas, M. Shiramizu, J. R. Lattner, B. Saha and
D. G. Vlachos, Appl. Catal., A, 2018, 552, 98–104.
Acknowledgements
This work was supported by the Swiss National Science
Foundation through grant CRSII5_180258 and by EPFL. We 23 G. Foyer, B.-H. Chanfi, D. Virieux, G. David and S. Caillol,
thank Dr Aurelién Bornet for the help with the NMR experiments,
Eur. Polym. J., 2016, 77, 65–74.
3466 | Green Chem., 2021, 23, 3459–3467
This journal is © The Royal Society of Chemistry 2021