Controlled production of the elusive metastable form II of acetaminophen (paracetamol): a fully scalable templating approach in a cooling environment.

A scalable, transferable, cooling crystallisation route to the elusive, metastable, form II of the API acetaminophen (paracetamol) has been developed using a multicomponent "templating" approach, delivering 100% polymorphic phase pure form II at scales up to 120 g. Favourable solubility and stability properties are found for the form II samples.