Page 172 - CW E-Magazine (12-12-2023)

Special Report

H -transfer reductive catalytic (lactic acid) which results in elongation Synthesis of carboxylic acid
2
fractionation (RCF) of lignocel- at break of the resulting blends. (ACS from saccharides, CO and H
lulose: High monomeric yield Sustainable Chem. Eng., 2023; DOI: 2 2
with switchable selectivity 10.1021/acssuschem.eng.3C01175). Y. Li et al have reported a strategy to
synthesise C7 carboxylic acids via the
Y. Li et al have used choline chloride Delignification and densifica- reaction of glucose, CO and H . Rh
2
2
(ChCl) to tailor the H -donating environ- tion as a route to enable the (acac) (CO) catalyst and I as promoter
2
2
2
ment of the Ru/C-catalysed H -transfer use of wheat straw (WS) for in the binary solvent of acetic acid and
2
RCF of lignocellulose. This reaction was structural materials water were deployed at 160°C. This
conducted under mild temperature and strategy has been applied to other C
n
pressure below 1 bar. Ethylene glycol F. Neudecker et al have referred to the saccharides, where the corresponding
(EG) was obtained at 190°C; when ChCl wide availability of WS and its poten- C n+1 carboxylic acids could be obtained
in EG was increased to 110 wt%, the tial. In this study lignin was partially and the yields could reach 72% when
selectivity of propylphenol switched toward removed from WS using an alkaline glyceraldehydes was used. (This is
propylene-phenol (yield of 36.2 wt% and solution to increase the relative cellulose an interesting and potentially useful
selectivity of 87.6%). (Angew. Chem. Intl. content and improving malleability. way of utilisation of biomass). (ACS
Ed.; DOI: 10.1002/anie.202307116). Then densification was done at elevated Catal., 2023; DOI: 10.1021/acscatal.
temperature and outstanding improve- 3C00374).
Environmentally friendly syn- ments in mechanical performance was
thesis of cardanol (C)-based realised and tensile strength increased Lignin (L)-enhanced wet
polyesters and their application by a factor of 3. This appears to be a strength of cellulose-based
as poly(lactic acid) additives viable method. (ACS Sustainable Chem. materials
[This column has covered some papers Eng., 2023; DOI: 10.1021/acssusche-
which cover valorisation of C, a non- meng.3C01375). H. Huang et al have referred to the poor
food item and a by-product of cashew wet strength of cellulose, which limits its
nut processing – an industry which is L catalytic depolymerisation for application as a high-strength material.
growing.] phenolic monomers This comprehensive review summarises
the current studies and describes the
A. Vallin et al have made a series of Z. Tang et al have worked on valori- mechanism. Different methods of pre-
C-derived diols, which can be used for sation of L via boosting the selecting paring cellulose-based materials are
polyesters and thus is encouraging from cleavage of β-O-G bonds of L by Mo=O analysed; the introduction of ionic or
renewable raw materials point of view and A1(IV)-O-BO interfacial sites in chemical crosslinking, or the thermal
2
as adipic acid and succinic acid are also B-Mo/sepiolite, which acted as Lewis curing of L-cellulose-based materials
bio-derived. Mild enzymatic catalysis in acid site. DFT calculations were done are covered. (Green Chem., 2023; DOI:
a solventless system was adopted. The and B content is important. Mo/SEP and 10.1039/D3GC01505J).
final workup procedure used methyl- B-Mo/SEP gave 99.3% L liquefaction
tetrahydrofuran, which is also bio-derived. and the highest selectivity of phenol at Lignin (L)-based bisguaiacol
The polyesters with molecular weights 48.5% and ethoxyphenol at 27.4%. (ACS diisocyanate (BGDI)
ranging from 1,800-2,400 g per mole Sustainable Chem. Eng., 2023; DOI:
were made and used to plasticise poly 10.1021/acssuschemeng.3C02036). S. Lemouzy et al have reported a
new bio-based aromatic diisocyanate
derived from lignocellulosic raw material,
namely guaiacol and vanillyl alcohol
and that too without using phosgene.
A three-step process is based on readily
available bisguaiacol F (BGF) and con-
version of aromatic amine into aromatic
isocyanate. The metal-free conversion
of BGF to bisguaiacol F diamine (BGA)
is described. Di-tert-butyldicarbonate
was used to make diisocyanate with a

172 Chemical Weekly December 12, 2023
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