Enhanced CO2 fixation in the biocatalytic carboxylation of resorcinol: Utilization of amines for amine scrubbing and in situ product precipitation

Reversible enzymatic decarboxylation reactions are known for their thermodynamic limitations regarding the carboxylation. Significant thermodynamic and kinetic improvements were achieved for the carboxylation of resorcinol by the 2,6-dihydroxybenzoic acid decarboxylase from Rhizobium sp. utilizing the amine scrubber triethanolamine for CO2 mediation. In a first approach, maximal yields of up to 50 % are achieved and are found to correlate with the CO2 loading capacity of triethanolamine. In a second approach, application of quaternary amines for in situ carboxylation product removal by precipitation improves the achievable yields depending on utilized amine concentration. This demonstrates the possibility for a reusable system. By variation of hydrated CO2 species ratio and concentration, CO2 and alternatively H2CO3 is identified acting as second substrate.

Automated summary

This study achieved significant improvements in thermodynamics and kinetics for the carboxylation of resorcinol by utilizing triethanolamine as a CO2 mediator, and employing quaternary amines for in situ carboxylation product removal by precipitation. It was found that CO2 and alternatively H2CO3 can act as a second substrate in this reversible enzymatic decarboxylation reaction.