What absorbs at 2879 cm⁻¹ in an FTIR spectrum?
A band near 2879 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 2879 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 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| C#c | 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 |
|---|---|---|---|
| Chitosan | 2879, 1650, 1655 | Alkyl C-H, Methacrylate, Hydroxyl (O-H) | 1 |
| cellulose | 2879, 1735, 1650 | Alkyl C-H, Methacrylate, Hydroxyl (O-H) | 1 |
| lignin | 2879, 1035, 1510 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 1 |
| hemicellulose | 2879, 1730, 897 | Alkyl C-H, Methacrylate, Hydroxyl (O-H) | 1 |
| sodium alginate | 2879, 1636, 1080 | Hydroxyl (O-H), Alkyl C-H, Methacrylate | 1 |
| curcumin | 2879, 1063, 1153 | Alkyl C-H, Methacrylate, 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 2879 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 -
Alkyl C-H confidence 1.0
“-NH2 (C-N Stretching) 2935.05cm-1 ±2935cm-1 Alkane(C-HStretching) (Medium) cm-1 cm-1 cm-1 and 2611.01 >3000 (Medium) Alkane (C-H Stretching) 2715.39 2879.43cm-1 and2868.32cm-1 ±2860cm-1 Alkane(C-HStretching) (Medium)”
Validation of the Developed Zero-Order Infrared Spectrophotometry Method for Qualitative and Quantitative Analyses of Tranexamic Acid in Marketed Tablets DOI: 10.3390/molecules26226985 -
Alkyl C-H confidence 1.0
“TheRamanspectraofallwaxes(Figure2a,b)aredominatedbythestrongbandsrelated cm-1 cm-1 to the CH stretching vibrations: the bands at 2879 and 2846 are attributed to x the symmetric stretching vibrations of methyl and methylene groups, respectiv”
Characterization of Waxes in the Roman Wall Paintings of the Herculaneum Site (Italy) DOI: 10.3390/app122111264 -
Alkyl C-H confidence 1.0
“N-H stretching 3105 N-H stretching 2879 -C-H stretching -C=O 1656 stretching (Amide I)”
Metal and Phosphate Ions Show Remarkable Influence on the Biomass Production and Lipid Accumulation in Oleaginous Mucor circinelloides DOI: 10.3390/jof6040260 -
Alkyl C-H confidence 1.0
“C-H stretching at 2879 cm-1 decreases with increasing Cel concentrations.”
Improvement of Chitosan Films Properties by Blending with Cellulose, Honey and Curcumin DOI: 10.3390/polym15122587 -
Lipid confidence 1.0
“sample through the vibrational and valence group peaks that belong to the structural sample through the vibrational and valence group peaks that belong to the structural cm-1), cm-1) components based on rosin (3443, 2939 and 2879 wax (2833,”
Sandu 等 - 2023 - Authentication of a Stradivarius Petite Violin T DOI: 10.3390/app -
Alkyl C-H confidence 1.0
“For CAU-10-H, the water cm-1 ν Furthermore, the bands at = 2879 and 1698 could molecules (w < 0.02 g/g) adsorb on strong surface sites with (C-H) (C-O) be assigned to and vibrations of amides, Q = 52 kJ/mol.”
Solovyeva 等 - 2021 - Water Vapor Adsorption on CAU-10-X Effect of Func DOI: 10.1021/acs.langmuir.0c02729 -
Alkyl C-H confidence 1.0
“Fourier-transform infrared spectroscopy of films The FTIR spectrum of the films (Figure 8a) shows cm-1 stretching,47 a peak at 2879 corresponding to C-H cm-1 and others at 1605 and 1409, 1350, and 1244 were”
Villacres 等 - 2023 - Preparation of Composite Films of Sodium Alginate- DOI: 10.21577/0103-5053.20230064
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