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.