What absorbs at 1374 cm⁻¹ in an FTIR spectrum?
A band near 1374 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 1374 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 |
|---|---|---|---|
| Alkyl C-H | 9 | 9 | 1.0 |
| Methacrylate | 6 | 6 | 1.0 |
| Acetate | 6 | 6 | 1.0 |
| Methoxy (OCH3) | 5 | 5 | 1.0 |
| C-O single bond | 5 | 5 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Amide | 3 | 2 | 1.0 |
| Lignin | 2 | 2 | 1.0 |
| Carbonate | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 0.8 |
| Secondary amine | 1 | 0 | 1.0 |
| C n single bond | 1 | 0 | 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 |
|---|---|---|---|
| chitosan | 1374, 1650, 1655 | Alkyl C-H, Acetate, Methacrylate | 1 |
| chitin | 1374, 1650, 1655 | Alkyl C-H, Methacrylate, Acetate | 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 1374 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
-
Alkyl C-H confidence 1.0
“3), it is clear that the cm-1), cm-1 valence vibrations of acetyl C =O groups (1745 alihighest value comes at 1732 intensity (associated cm-1), phatic C-H deformation vibrations in CH (1374 to acetyl C =O groups), which registers a coeffici”
Acetylation of tropical hardwood species from forest plantations in Costa Rica: an FTIR spectroscopic analysis DOI: 10.1186/s10086-020-01898-9 -
confidence 1.0
“The absorption peaks at 1374 and 1255 were ascribed to N-H bending vibrations of primary amides and C-O-C stretching vibrations in both chitosan samples.”
Antimicrobial Activity of Chemically and Biologically Treated Chitosan Prepared from Black Soldier Fly (Hermetia illucens) Pupal Shell Waste DOI: 10.3390/microorganisms9122417 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Lyu 等 - 2019 - XPS and FTIR studies of fungus-stained Daemonorops DOI: 10.1007/s11676-018-0598-5 -
confidence 1.0
“spectrum showed peaks at 1374cm and were found to be 3.71ug/mg and 11.25ug/mg for valsartan and 1.52ug/mg Among which N-H (stretching) group showed clear, intense peak which and 4.61ug/mg for hydrochlorothiazide respectively.”
Rahman 等 - 2020 - Development and Validation of Chemometric Assisted DOI: 10.5530/jyp.2020.12s.46 -
Alkyl C-H confidence 1.0
“to the asymmetric deformation of the CH scissoring mode of 2 cm-1 the methylene groups whereas the peak around 1374 is associatedwiththesymmetricdeformationmodevibrationsof cm-1 Between 3000 and 2800 the methyl groups of PEO blocks.”
Studies of the behavior of reverse nonionic surfactant Pluronic 31R1 in aqueous and Propylammonium acetate (PAAc) ionic liquid solutions DOI: 10.1007/s10965-020-02315-x -
Alkyl C-H confidence 1.0
“2A 3A This study has discovered that ELF have the potential to (symmetric and asymmetric CH and CH stretching vibration), from1374.26cm(cid:1)1to1372.96cm(cid:1)1(CH decolorize MG dye.”
Decolourization of malachite green dye by endolichenic fungi from the lichen Usnea sp.: A novel study on their dye removal potential DOI: 10.1016/j.jksus.2021.101579 -
Carbonate confidence 1.0
“The wide valley between 1538 cm-1 and 1374 is the characteristic absorption of calcite type, which represents the asymmetric stretching vibration”
Cui 等 - 2015 - Preparation of CaCO3-SiO2 composite with core-shel DOI: 10.1515/pjct-2015-0079 -
Acetate confidence 1.0
“87 85 82 Amine C-Nstretching 1162 80 72 73 C-O stretching Tertiary alcohol 1374 90”
A Comparison of Water Imbibition and Controlled Deterioration in Five Orthodox Species DOI: 10.3390/agronomy12071486
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