What absorbs at 2874 cm⁻¹ in an FTIR spectrum?
A band near 2874 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 2874 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 | 11 | 11 | 1.0 |
| Methyl | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 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 |
|---|---|---|---|
| Methacrylate | 2874, 873, 1725 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| polystyrene | 2874, 1020, 1600 | Alkyl C-H, Amide, Hydroxyl (O-H) | 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 2874 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
“In particular, the peaks at 2874cm-1 2956and may be attributed to asymmetric and symmetric cm-1 stretches of methyl (CH 3) groups, and those at 2922 and 2852 to asymmetric and symmetric stretching peaks of methylene (CH 2) groups (Senesi an”
Clabel 等 - 2020 - Organo-mineral associations in a Spodosol from nor DOI: 10.1016/j.geodrs.2020.e00303 -
confidence 1.0
“Explicit assignment: 'CH sym vibration (2874)'”
Shi 等 - 2018 - Biochemical alterations of Candida albicans during DOI: 10.1039/c8an01452c -
Alkyl C-H confidence 1.0
“cm-1 cm-1 stretching), ~2921 (CH antisymmetric stretching), ~2874 (CH symmetric 2 3 To this aim, in Figure 5A, we reported the second derivative spectra of ATX3-Q24 cm-1 stretching), and ~2852 (CH symmetric stretching) [42].”
Pathological ATX3 Expression Induces Cell Perturbations in E. coli as Revealed by Biochemical and Biophysical Investigations DOI: 10.3390/ijms22020943 -
confidence 1.0
“Furthermore, bands at 1260 and 1352 represent cm-1 cm-1 C-F bending, while bands at 2874 and 3656 represent O-H stretching due to the hydration of cement.”
Assiry 等 - 2023 - Microstructural and Elemental Characterization of DOI: 10.3390/app13074517 -
Alkyl C-H confidence 1.0
“The bands with maxima at 2954 and cm-1 2919 correspond to CH stretching vibrations, and the dominant bands at 2874 and 3 cm-1 2850 assigned to the CH stretching vibrations are derived from saturated aliphatic”
Optimization of Electrochemical Visualization of Latent Fingerprints with Poly(Neutral Red) on Brass Surfaces DOI: 10.3390/polym13193220 -
Alkyl C-H confidence 1.0
“The bands at 2957 and 2874 cm-1 are assigned to the methyl group's symmetric and asymmetric stretching vibrations of C-H bonds [32].”
Dibutyl Itaconate and Lauryl Methacrylate Copolymers by Emulsion Polymerization for Development of Sustainable Pressure-Sensitive Adhesives DOI: 10.3390/polym14030632 -
confidence 1.0
“Explicit assignment: 'assigned to ... vsCH3'”
Monitoring oocyte-based human pluripotency acquisition using synchrotron-based FTIR microspectroscopy reveals specific biomolecular trajectories DOI: 10.1016/j.saa.2023.122713 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Simultaneous small-angle neutron scattering and Fourier transform infrared spectroscopic measurements on cocrystals of syndiotactic polystyrene with polyethylene glycol dimethyl ethersThis article will form part of a virtual special issue of the journal, presenting some highlights of the 16th International Conference on Small-Angle Scattering (SAS2015). DOI: 10.1107/S160057671601178X
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