Effects of solvents and impurity on crystallization kinetics and crystal properties in a reactive crystallization of paracetamol

The effect of three solvents which are mixtures of water and acetic acid of different compositions on crystallization kinetics and crystal properties is reported. The nucleation orders for the three solvents used in this work are comparable, but higher than published data. The growth rates are similar to that of recrystallization work. Different solvents can deliver the same supersaturation, but crystal shapes change from column to needle-like. Different solvent compositions can also give rise of different levels of impurity due to the side reaction, their effects on crystal morphology and purity are discussed. We demonstrate that the reagents and solvents from the reaction step are the means for controlling and delivering required crystal properties when both reaction and crystallization are carried out in a continuous fashion.