Concomitant cocrystal and salt: no interconversion in the solid state

A cocrystal and a molecular salt of β‐alanine and dl ‐tartaric acid, C₃H₈NO₂⁺·C₄H₄O₆^?, of the same chemical composition, were studied over a wide temperature range by single‐crystal and powder X‐ray diffraction. Neither the interconversion between the two phases nor any polymorphic transitions were observed in the temperature range from 100 K to the melting points. This contrasts with the solvent‐mediated phase transition from the salt to the cocrystal in a slurry that has been documented earlier.