# Catalytic Reductive Fractionation of Castor Shells into Catechols via Tandem Metal Triflate and Pd/C Catalysis

## TL;DR

This paper presents a new method to efficiently convert castor shells into valuable catechol monomers using a combination of metal catalysts.

## Contribution

A tandem catalytic system using Pd/C and In(OTf)3 is introduced for high-yield and high-selectivity production of catechols from castor shells.

## Key findings

- The Pd/C + In(OTf)3 combination achieved a 66.9 mg·g−1 yield of aromatic monomers.
- Catechol selectivity reached 95.4% using the optimized catalytic system.
- In3+ promotes C–O bond cleavage and accelerates the release of catechol monomers from C-lignin.

## Abstract

In this work, the one-pot catalytic reductive fractionation of C-lignin in castor shell powders to efficiently provide catechyl monomers was achieved by tandem metal triflate and Pd/C catalysis. The optimized Pd/C + In(OTf)3 combination performed best and provided a 66.9 mg·g−1 yield of corresponding aromatic monomers with the catechol selectivity as high as 95.4%. For the promotion effect of the Lewis acid species, the mechanism studied indicated that the introduction of In3+ could significantly promote the C–O bond cleavage in the LCC to release the C-lignin fragments from the solid lignocellulose and simultaneously accelerate the cleavage of the critical Cα/β–OAr linkage bond in C-lignin to release catechol monomers. In addition, performance differences highlight the cooperation and function-matching effect between the hydrogenation metals and the Lewis ion species, which can promote the high-value utilization of forestry and agricultural residues in chemical synthesis.