What absorbs at 3451 cm⁻¹ in an FTIR spectrum?
A band near 3451 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
A band near 3451 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
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Hydroxyl (O-H) | 10 | 10 | 1.0 |
| Water (H2O) | 3 | 3 | 1.0 |
| N h | 3 | 2 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Metal hydroxyl | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| PVP | 3451, 2983, 1648 | Hydroxyl (O-H) | 1 |
| geopolymer | 3451, 1453, 1000 | Hydroxyl (O-H), Water (H2O) | 1 |
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 3451 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
“Figure.3 showed that the mid-strong 3451cm-1 peak at was the O-H stretching vibration absorption peak, the C-H stretching vibration cm-1,2959cm-1, 2929cm-1, 2879cm-1, 2746cm-1, absorption peaks were located at 3061 and the peaks 2247cm-1, 2”
Li 等 - 2011 - The detection of Cypermethrin on the surface of Ap DOI: 10.4028/www.scientific.net/AMR.287-290.2991 -
Hydroxyl (O-H) confidence 1.0
“For PVP, the band located at 3451 is attributed to the symmetric vibration of - cm-1 OH group, the bands at 2954 and 1463 correspond to the -CH absorptions of PVP.”
Qureshi 等 - 2015 - Ethyl acetate Salix alba leaves extract-loaded chi DOI: 10.1080/09205063.2015.1100843 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Abd Rahman 等 - 2014 - UV-Curable Acrylated Coating From Epoxidized Palm DOI: 10.1063/1.4895237 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Experimental and DFT studies on the structural and optical properties of chitosan/polyvinyl pyrrolidone/ZnS nanocomposites DOI: 10.1007/s00289-023-04700-0 -
Hydroxyl (O-H) confidence 1.0
“On the other hand, 1641cm-1 characterization of the OMW samples were operated as the peak at is for H-O-H bending, and the stretchingvibrationofOHappearsataround3451cm-1.The executed in the previous work [2].”
Al-Essa 和 Al-Essa - 2021 - Effective Approach of Activated Jordanian Bentonit DOI: 10.1155/2021/7405238 -
Alkyl C-H confidence 1.0
“e vibrational stretching of C= O group, whereas poloxamer and with increase in pH for pH cm-1 3451.0 band was attributed to C-H dependent polymer i.e.”
Anuml 等 - 2021 - Development and characterization of ceftriaxone in DOI: 10.4314/tjpr.v20i4.2 -
Hydroxyl (O-H) confidence 1.0
“The wavenumber of the -OH stretching peak decreased from 3450.62 and cm-1 cm-1”
Dipentaerythritol penta-acrylate phosphate - an alternative phosphate ester monomer for bonding of methacrylates to zirconia DOI: 10.1038/srep39542 -
Hydroxyl (O-H) confidence 1.0
“The IR band locm-1 at 3451 is attributed to symmetrical and antisymmetric elongation vibrations of the cated at 3451 cm-1 is attributed to symmetrical and antisymmetric elongation vibrations H-O bond in water molecules.”
The Influence of Substitution of Fly Ash with Marble Dust or Blast Furnace Slag on the Properties of the Alkali-Activated Geopolymer Paste DOI: 10.3390/coatings13020403
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