• Top library match: 4-methylbenzenesulfonic acid hydrate #19198

• The top library match, 4-methylbenzenesulfonic acid hydrate, would require sulfonate S=O stretching bands around 1350–1150 cm⁻¹, which are not clearly resolved in the spectrum; the 2175 cm⁻¹ band is also incompatible with that structure.
• Low library similarity, the absence of confirmatory aromatic C–H out‑of‑plane bending modes, and the lack of distinct sulfonate bands limit the confidence in a precise molecular identification.
• The 2175 cm⁻¹ band is assigned tentatively to a nitrile group and may arise from a minor component or impurity.

Recommended next steps: Examine the 1400–1000 cm⁻¹ region for sulfonate S=O vibrations to test the sulfonic acid hypothesis. Confirm the nitrile assignment of the 2175 cm⁻¹ band by Raman spectroscopy or elemental analysis. Consider a purified sample or hyphenated techniques (e.g., GC‑IR, pyrolysis‑GC‑MS) to resolve the composition.