Comparison of the methyl ester of l‐tyrosine hydrochloride and its methanol monosolvate

Solvent‐free (2S)‐methyl 2‐ammonio‐3‐(4‐hydroxy­phenyl)­propionate chloride, C₁₀H₁₄NO₃⁺·Cl⁻, (I), and its methanol solvate, C₁₀H₁₄NO₃⁺·Cl⁻·CH₃OH, (II), are obtained from different solvents: crystallization from ethanol or propan‐2‐ol gives the same solvent‐free crystals of (I) in both cases, while crystals of (II) were obtained by crystallization from methanol. The structure of (I) is characterized by the presence of two‐dimensional layers linked together by N—H⋯Cl and O—H⋯Cl hydrogen bonds and also by C—H⋯O contacts. Incorporation of the methanol solvent mol­ecule in (II) introduces additional O—H⋯O hydrogen bonds linking the two‐dimensional layers, resulting in the formation of a three‐dimensional network.