Page 167 - CW E-Magazine (24-12-2024)

Special Report

Heterogeneously catalysed and enzymatic processes of phenolic investigated using operando photoelec-
reductive depolymerisation extraction and their bioactivity. Chloro- tron photoion coincidence (PEPICO)
(HCRD) of Lignin (L) to genic acid is an important product. Thus spectroscopy to unveil the reaction
value-added chemicals the use of organic solvents can be avoided. mechanism by detecting reactive
(ACS Sustainable Chem. Eng., 2024; intermediates, such as quinone methides
Z. Yu et al have reported the title strategy DOI: 10.1021/acssuschemeng.4C02718). and ketenes, and products. Detailed
as a promising approach to facilitate mechanism is given in the paper. This
selective bond cleavage in L and H Lignin (L) study is directed towards using mecha-
2
transfer to stabilise the products under Solvent-free L modification nistic insights to arrive at strategies to
mild condition. This is a comprehensive through ball-milled CuAAc fine tune process conditions to increase
review where reduction could be through the selectivities of desired products by
H , alcohols, formic acid, etc. and both Y. Sang et al have worked on ball-milled enhancing either vanillin and guaiacol or
2
precious and non-precious metal catalyst mechanochemistry, which avoids the use suppressing eugenol yields from native
are used; the role of supports is also of solvents; resulting in cost reduction L. (Green Chem., 2024; DOI: 10.1039/
covered. Diverse arrays of high-value and it becomes greener. The L-alkyne D4GC03143A).
aromatic chemicals are obtained. and ethylazidoacetate are ball milled
(ChemSusChem, 2024; DOI: 10.1002/ with a catalyst of Cu(OAc) at 600 rpm. Bioactive extraction from
2
cssc.202401399). Full conversion was realised in 30 min cashew apple (CA)
on L model compounds of vanillin, V.R. Shirsat et al have carried out work
Effects of extraction processes 2-methoxy-4- methylphenol, and 2-me-
on recovery, the phenolic thoxy-4-propylphenol. For natural Ls, on method for extracting bio-actives
profile, and antiglycation the reaction reaches 89% conversion from dried CA. Mathematical model-
ling has been done and Maxwell-Stefan
activity from green coffee for enzymolysis L-alkyne and 93% con- approach has been adopted to resolve
residues (coffea arabica and version for dealkali L-alkyne within 30 effect of internal diffusivity and external
coffea canephora Pierre) minutes. Various azides were then used. mass transfer. This work is important as
(ACS Sustainable Chem. Eng., 2024; world-over annually 2.2 giga-tons of CA
E.C.P.P. Dias et al have referred to coffee DOI: 10.1021/acssuschemeng.4C00183). is produced and of this 80% are wasted.
processing, which generation tonnes CA is good source of polyphenols and
of residues that cause environmental Catalytic pyrolysis mechanism tannins (high molecular weight poly-
problems and loss of economics. Green of L moieties driven by phenols). Optimised parameters for ex-
coffees are rich in phenolic compounds aldehyde, hydroxyl, methoxy traction are reported. (Sepn. Purfn. Tech-
that have a strong antioxidant capacity and allyl functionalisation nol., 2025, 354, Part6, 19 Feb.129215;
and the ability to prevent the production DOI:10.1016j.seppur.2024.129215).
of advanced glycation agents (AGES). Z. Pan et al have worked on the cata-
This study was aiming to evaluate the lytic pyrolysis of guaiacol (G)-based Efficient metal-acid
effect of different physical (low tempera- L monomers, vanillin, syringol, and bifunctional catalysts
ture vacuum, LTV, and double milling) eugenol over commercial HZSM-5 and
derived from NiAl-LDO
for the reductive catalytic
fractionation (RCF) of
lignocellulose (LC) into
phenolic monomers
[This column has covered a large num-
ber of papers on this contemporary
subject of valorising lignocellulosic
materials.]
X. Yang et al have opined that RCF
is a promising way to obtain phenolic
monomers without using noble metal
catalysts. A reduced NiAl layered double

Chemical Weekly December 24, 2024 167

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