• トップライブラリ一致: 4-methylbenzenesulfonic acid hydrate #19198

• The absence of strong sulfonic acid S–O stretching bands (expected near 1170–1150 cm⁻¹ and 1350–1300 cm⁻¹) argues against 4‑methylbenzenesulfonic acid hydrate as the sole or primary component.
• The 2175 cm⁻¹ band could represent a C–N or nitrile vibration, but the spectrum lacks other characteristic nitrile modes and does not show a prominent N–H stretch, making a purely nitrile‑containing structure less likely.
• The exact molecular identity cannot be deduced from FTIR alone; the spectrum likely reflects a mixture of structural units or a composite material.
• The assignment of the 1164 cm⁻¹ band remains ambiguous between alkyl C–H and C–O stretching, and further analysis is needed to clarify its origin.
• The 2175 cm⁻¹ feature is consistent with both a carboxylic acid combination band and a C–N stretching vibration, leaving ambiguity about the presence of a free carboxylic acid or a nitrogen‑containing functionality.

推奨される次のステップ: Perform LC‑MS or GC‑MS to elucidate the molecular mass range and fragmentation pattern of the ester and amide constituents. Employ ¹H and ¹³C NMR spectroscopy to determine the aromatic substitution pattern and to confirm the presence of glycosidic linkages. If a conjugate or composite is suspected, chemical derivatization (e.g., hydrolysis) followed by HPLC or TLC analysis could help identify the carbohydrate and amide/acid moieties.