What absorbs at 3612 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3612 cm⁻¹ is usually interpreted by checking which functional groups repeatedly co-occur there in the literature, then confirming at least one or two additional peaks in the same sample. This page ranks those assignments by accumulated evidence rather than by a single fixed textbook rule.

Possible functional-group assignments

Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.

Possible materials

Materials are shown only when the same literature pool supports this band and at least one additional characteristic peak.

Spectrum logic

This band becomes meaningful only when read with its neighboring peaks. In practice, analysts first look at the assignments above, then check whether the same sample also shows other peaks expected for the same structural motif. A lone band near 3612 cm⁻¹ is usually not enough for material identification by itself.

Real-world usage

This type of query is common in polymer identification, unknown plastic screening, QC troubleshooting, recycled-material verification, and literature-backed peak assignment review.

Common mistakes

• Treating one isolated band as proof of a material without checking at least one or two supporting peaks.
• Ignoring overlap: multiple functional groups can contribute near the same wavenumber.
• Skipping validation when additives, blends, oxidation, or contamination may distort the spectrum.

Verification advice

When ambiguity remains, validate the hypothesis with DSC, GC-MS, or TGA, especially for blends, degraded samples, and filled polymers.

Literature behind these assignments

• Hydroxyl (O-H) confidence 1.0

  “The polarizations cm-1 of the OH bands at 3612, 3578, 3566, 3551, 3477 are well constrained.”

  Liu 等 - 2019 - In Situ Infrared Spectra for Hydrous Forsterite up DOI: 10.3390/min9090512
• Hydroxyl (O-H) confidence 1.0

  “The solubility in on absorption bands around 3700-3400 cm-1 water and the atomic radius were the main fac- [23] and hydroxyl stretching vibration at 3612 tors that result in the low levels of potassium”

  Natural Clay of Pasaman Barat Enriched by CaO of Chicken Eggshells as Catalyst for Biodiesel Production DOI: 10.9767/bcrec.15.3.8097.662-673)
• Hydroxyl (O-H) confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Foliar Application of Nanoclay Promotes Potato (Solanum tuberosum L.) Growth and Induces Systemic Resistance against Potato Virus Y DOI: 10.3390/v14102151
• Hydroxyl (O-H) confidence 1.0

  “Jung, 2009), whereas cm-1 the peak at 3612 is most likely related to OH incorporated as Mg 2[]OH 4, where [] cm-1 represents an Si vacancy (Berry et al.”

  De Hoog 等 - 2014 - Titaniumand water-rich metamorphic olivine in hi DOI: 10.1007/s00410-014-0990-x
• Hydroxyl (O-H) confidence 1.0

  “cm-1in the same vibration for the free OH groups gives rise to a narrow band at 3612 diluted cm-1 CCl solutions and to a broader component at 3617 when adsorbed on dehydroxylated”

  Mino 等 - 2016 - A surface science approach to TiO2 P25 photocataly DOI: 10.1016/j.apcatb.2016.05.029
• Bromine confidence 1.0

  “cm-1 ν(OH) In contrast, the band at 3612 is attributed to free of Brønsted acidic 𝜈̅(𝑂𝐻) In contrast, the band at 3612 cm-1 is attributed to free of Brønsted acidic groups that are predominantly within the micropores [47].”

  Pore Blocking by Phenolates as Deactivation Path during the Cracking of 4-Propylphenol over ZSM-5 DOI: 10.3390/catal11060721
• Hydroxyl (O-H) confidence 0.8

  “Negative band at 3612 represents formation of strong H-bond or proton release.”

  Noguchi - 2008 - FTIR detection of water reactions in the oxygen-ev DOI: 10.1098/rstb.2007.2214