Page 166 - CW E-Magazine (19-8-2025)

Special Report

Metal-free catalysis is transforming the future

of sustainable pharmaceutical innovation

he pharmaceutical industry today CHINMOY HAZRA
faces a pressing dual challenge:
Taccelerating the discovery of Associate Professor
Department of Chemistry
innovative therapies while dramatically Indian Institute of Technology, Delhi
reducing its environmental footprint.
Estimates indicate that global pharma- green credentials. Unlike Lewis acid
ceutical emissions account for approxi- or metal-based systems, Brønsted
mately 52-million tonnes of CO₂ each acid catalysis employs proton donors,
year, surpassing even the automotive organic acids such as sulphonic acids
sector in emissions intensity. The call or phosphoric acids, to activate sub-
for greener, more sustainable chemis- strates via hydrogen-bonding or
try has become imperative. Alongside protonation in chemical transformation.
rising research and development costs, These acids are typically less toxic,
tightening regulations are compelling more aff ordable, and readily available,
companies to reevaluate long-esta- making them ideal for scale-up in
blished methods of chemical synthesis. industrial settings.
In this context, metal-free catalysis has metals have played an indispensable
emerged as a promising strategy for role in driving reactivity and selecti- Mechanistically, Brønsted acids can
designing safer, cleaner, and more vity across a wide range of transforma- facilitate a broad range of reactions,
scalable routes to complex drug mole- tions. Yet they also introduce notable including C-C (carbon–carbon) bond
cules. drawbacks. Many are scarce, expen- formation, cyclizations, rearrange-
sive, and toxic in even trace quantities. ments, and condensations, many of
Recent market studies refl ect this To comply with international health which are essential in the development
momentum. The global green chemi- regulations, companies must invest of active pharmaceutical ingredients
cals market is projected to reach signifi cant resources to remove resi- (APIs). This mechanism not only off ers
$167.9-bn by 2030, with a CAGR of dual metals from drug products, adding effi ciency but also opens pathways to
10.8%. This expansion is driven by further environmental and economic molecular complexity without com-
growing regulatory scrutiny, evolving burden. promising environmental standards.
investor expectations, and recogni- In many cases, they can be employed
tion across the sector that sustainable Metal-free catalysis provides a under milder reaction conditions and
processes can improve operational compelling alternative. Rather than are compatible with aqueous media,
resilience and long-term competitive- relying on precious or critical metals, further reducing the environmental
ness. these systems employ organic acids and energy footprint of the process.
or small-molecule organocatalysts to Additionally, their homogeneous nature
Among the various approaches mediate reactions. The result is a mea- allows for better control and reproduci-
gaining ground, Brønsted acid cata- surable reduction in hazardous waste, a bility during scale-up, which is critical
lysis stands out for its capacity to lower risk of contamination, and fewer in pharmaceutical manufacturing.
balance environmental benefi ts with energy-intensive purifi cation steps. As
robust performance in pharmaceutical environmental regulations continue to One of the key advantages of this
synthesis. evolve, metal-free catalysis is becom- approach is the potential for reusability.
ing less of a niche innovation and more Recent studies have demonstrated that
Why sustainable catalysis is now of a viable standard for the industry. carefully designed Brønsted acid sys-
a necessity tems can be recycled across multiple
For decades, pharmaceutical pro- Understanding Brønsted acid catalysis reaction cycles without signifi cant loss
cesses have depended heavily on transi- Among emerging solutions, Brøn- in activity. Strong organic Brønsted acids
tion metal-based catalysts such as palla- sted acid catalysis is gaining traction can achieve high catalytic effi ciency at
dium, rhodium, and ruthenium. These due to its simplicity, accessibility, and low concentrations, producing minimal

166 Chemical Weekly August 19, 2025

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