Thermal Stability of 2-Butynoic Acid (Tetrolic Acid)

Work to assess the thermal properties of 2-butynoic acid (a precursor to acalabrutinib) has revealed the potential for thermal runaway on heating; testing using accelerated rate calorimetry (ARC) showed exothermic onset from 135 °C, precluding short-path distillation as a means of purification. Recrystallization was shown to be effective as an alternative technique to purify the compound and avoid the distillation procedure.