Intensified, Kilogram-Scaled, and Environment-Friendly: Chemoenzymatic Synthesis of Bio-Based Acylated Hydroxystyrenes

Lignin-derived styrene derivatives are versatile building blocks for the manufacture of bio-based polymers. As shown previously, phenol-protected hydroxystyrenes are accessible under industrially-sound conditions (>100 g/L, >95% yield) by subjecting biogenic phenolic acids to enzymatic decarboxylation and base-catalyzed acylation in non-aqueous media (wet cyclopentyl methyl ether, CPME). Herein, we demonstrate the production of 1 kg of 4-acetoxy-3-methoxystyrene in a 10 L reactor and present practical adjustments to the up- and downstream processing that warrant a straightforward process and high isolated yields. Additionally, an environmental assessment is conducted, starting with a thorough E factor analysis to identify the sources that contribute most to the environmental burden (solvent and downstream processing). Also, the total CO2 production of the process is studied, including contributions from energy use and the treatment of generated wastes. The energy impact is evaluated through thermodynamic analysis, and the environmental footprint contributions by wastes – organic and aqueous fractions – are assessed based on CO2 emissions from solvent incineration and wastewater treatment, respectively. Overall, the holistic assessment of the process, its optimization, scale-up, product isolation, and environmental analysis indicate the feasibility of multi-step chemoenzymatic reactions to deliver high volume, low-value chemicals from biorefineries.