Preparation of polymorphic crystalline phases of d-mannitol: influence of keggin heteropolyanions

Two crystalline forms of d-mannitol precipitated at room temperature from acetone/water mixtures in the presence of the Keggin heteropolyanions [PW12O40]3− or [SiW12O40]4− were identified by X-ray powder diffraction and solid state 13C NMR spectroscopy. In the presence of [SiW12O40]4− (acid or K+ salt) the α polymorph was the only form obtained. The κ form was the predominant component of a mixture of κ and α forms obtained in the presence of H3[PW12O40]. In the absence of the polyanions, the β form was precipitated.