What absorbs at 2974 cm⁻¹ in an FTIR spectrum?
A band near 2974 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 2974 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 | 16 | 12 | 1.0 |
| Methyl | 2 | 2 | 0.95 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| N n bond | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 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 |
|---|---|---|---|
| Nanotubes | 2974, 1735, 1630 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 1 |
| zinc oxide | 2974, 1627, 1638 | Methacrylate, Alkyl C-H, Methoxy (OCH3) | 1 |
| bone | 2974, 1649, 1660 | Alkyl C-H | 1 |
| zinc oxide nanoparticles | 2974, 1744, 1627 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 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 2974 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
“LLM confirmed rule peak-group candidate”
Surface modification of zinc oxide nanoparticles by vinyltriethoxy silane (VTES) DOI: 10.1016/j.inoche.2020.108347 -
confidence 1.0
“3: the symmetric stretching at 3057 and 3018 the ¼¼CH cm(cid:2)1 band centered at 1002 is associated with the Si-O-Si asymmetric and symmetric stretching at 2974 and 2935”
Aresta 等 - 2012 - Initiated-chemical vapor deposition of organosilic DOI: 10.1116/1.4711762 -
Alkyl C-H confidence 1.0
“The bands at 2974 cm-1 and 2870 are characteristic to the stretching vibrations of the C-H bonds [16-17].”
Dippong 等 - 2017 - THE EFFECT OF POSITIONAL ISOMERISM OF PROPANEDIOL DOI: 10.24193/subbchem.2017.4.02 -
N n bond confidence 1.0
“The FTIR spectrum of Ethyl cellulose FTIR studies were performed to know the interaction exhibits following characteristics peaks such as at, cm-1 cm-1 between different excipients and drug which was used for N-N stretching, 2974 for C-H 34”
Dubey 和 Dewangan - 2020 - Rational Design and Characterization of Transderma DOI: 10.5530/ijper.54.3s.145 -
Alkyl C-H confidence 1.0
“Characteristic bands of cm-1 (N-H stretching), 2973.5 cm-1 (C-H stretching), 2695.0 cm-1 (O-H stretching), 1720.6 cm-1 (C=O”
Garbacz 和 Wesolowski - 2018 - DSC, FTIR and Raman Spectroscopy Coupled with Mult DOI: 10.3390/molecules23092136 -
Alkyl C-H confidence 1.0
“250 (protein methyl torsion), 1250 (amide III), 1450 (CH deformation), 1550 (amide II), 1660 2 cm-1 (amide I) and 2974 (CH stretching).”
Marques 等 - 2018 - Heat-induced Bone Diagenesis Probed by Vibrational DOI: 10.1038/s41598-018-34376-w -
Carbonyl (C=O) confidence 1.0
“cm-1), cm-1), (3441 aromatic and alkene C-H stretching vibrations (3018 alkane C-H cm-1), stretching vibration (2974 aromatic conjugated C=O stretching vibration (1691 cm-1), cm-1), C=C aromatic stretching vibration (1620, 1598, 1516, 1431”
Age-dependent Fecundity of Podisus nigrispinus (Heteroptera: Pentatomidae) at Sublethal Doses of Gammacyhalothrin DOI: 10.1590/1678-4324-2018170809 -
Alkyl C-H confidence 1.0
“cm-1 The bands widened between 3500 and 3252 referring to the striation band The bands widened between 3500 and 3252 cm-1 referring to the striation band of the cm-1, of the group (OH), mainly O-H stretching bands at 3338 C-H vibrations nea”
Rutin-Functionalized Multi-Walled Carbon Nanotubes: Molecular Docking, Physicochemistry and Cytotoxicity in Fibroblasts DOI: 10.3390/toxics9080173
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