A new crystalline form of αβ-D-lactose prepared by oven drying a concentrated aqueous solution of D-lactose

A new crystalline form of αβ-D-lactose (C₁₂H₂₂O₁₁) has been prepared by the rapid drying of an approximately 40% w/v syrup of D-lactose. Initially identified from its novel powder X-ray diffraction pattern, the monoclinic crystal structure was solved from a microcrystal recovered from the generally polycrystalline mixed-phase residue obtained at the end of the drying step. This is the second crystalline form of αβ-D-lactose to be identified and it has a high degree of structural three-dimensional similarity to the previously identified triclinic form.