Abstract
The thermal hazard assessment of cyclohexane-type liquid crystal monomers (CLCMs) from the Grignard cross-coupling reaction is challenging because the thermal hazard assessment involves the Grignard reagent. In this study, different calorimeters in semi-batch and batch modes were used to investigate the exothermic behaviour of CLCM. The enthalpy of formation of the Grignard reagent (320.87 - 380.46 kJ mol−1) was higher than that of the cross-coupling reaction (70.92 - 108.68 kJ mol−1). The heat accumulation in semi-batch mode decreased to 12.15% when compared with 100% observed in batch mode. Furthermore, the Grignard reagent decomposed at 470.39 K, with a low activation energy (Ea) of 110.99 - 129.67 kJ mol−1. Finally, based on the Stoessel criticality diagram, the thermal risk of the CLCM was found to be class 4 in batch mode and class 3 in semi-batch mode. This revealed that the semi-batch mode was the most suitable dosing method for CLCMs.
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