DCM alternatives for use in Steglich esterifications, for green and sustainable liquid crystal syntheses

Dichloromethane (DCM) is a popular solvent for the synthesis of liquid crystalline materials owing to its solvating power, moderate polarity, and ease of removal. The environmental and toxicological issues surrounding DCM prompt us to explore alternatives. Here, we have screened an extensive selection of green and sustainable solvents to find the most efficacious DCM alternative for the synthesis of a conventional liquid crystal, CZP-5-N. Several factors are considered: yield, environmental impact, and health and safety concerns. The best performing solvent, dimethyl carbonate, was then used in the synthesis of common and novel liquid crystals, along with intermediates, giving excellent results, even for electron poor phenols. With esterifications prevalent in trending research areas like the ferroelectric nematic phase, this work allows a facile means for sustainability to be incorporated into synthetic pathways.