What absorbs at 2917 cm⁻¹ in an FTIR spectrum?
A band near 2917 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 2917 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 | 41 | 39 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| Acetate | 5 | 5 | 1.0 |
| Methyl | 4 | 4 | 1.0 |
| Carbohydrate | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Fatty acid | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| N-O bond | 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 |
|---|---|---|---|
| PVA | 2917, 1660, 2930 | Alkyl C-H, Acetate, Methacrylate | 1 |
| PMMA | 2917, 1722, 1383 | Methacrylate, Acetate, Alkyl C-H | 1 |
| biochar | 2917, 1640, 1115 | 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 2917 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
“cm-1 Aand Bsites IR-spectrum of BaM sample shows the band around 2917 and 3416 assign O-H cm-1, CO2stretching of water, the N-O elongating at about 1481-1484 vibration of anti-symmetrical at α-Fe cm-1, cm-1, 1642 and 2O stretching metal-O a”
Effect of rare earth and transition metal La-Mn substitution on electrical properties of co-precipitated M-type Ba-ferrites nanoparticles DOI: 10.1016/j.jre.2018.08.005 -
Acetate confidence 1.0
“The C-O stretching in amino carboxylic acid have been found to appear at 2917 and 2848 cm-1, respectively [18].”
Aziz 等 - 2017 - From Insulating PMMA Polymer to Conjugated Double DOI: 10.3390/polym9110626 -
Alkyl C-H confidence 1.0
“C-O stretching) and CH (3287.49 -OH stretching, 2917.48 -CH stretching) maintain their place in PVA/CH and PVA/CH/Ag hydrogels.”
Sprayed in-situ synthesis of Polyvinyl alcohol/Chitosan loaded Silver nanocomposite hydrogel for improved antibacterial effects DOI: 10.1016/j.ijbiomac.2019.09.186 -
Alkyl C-H confidence 1.0
“ther decreased to 0.04% when intercalated HDTMA was 0.75 CEC 2850cm-1 The CH stretching bands near 2917 and are genandremainedthesameeventhoughtheHDTMAloadingincreased”
Li 等 - 2008 - An FTIR investigation of hexadecyltrimethylammoniu DOI: 10.1016/j.saa.2008.05.015 -
Alkyl C-H confidence 1.0
“Figure 5 shows the FTIR spectra of the initial and final tomato waste, being able to observe the most intense peak at the 3361 cm-1 wavelength belonging to the N-H bond, OH groups, carboxylic acids and phenolic groups, while the peak at 291”
Green Energy Generated in Single-Chamber Microbial Fuel Cells Using Tomato Waste DOI: 10.3390/su151310461 -
Alkyl C-H confidence 1.0
“The peak at 2917 and 2850 is C-H stretching in cellulose.”
Production of non-activated biochar based on Biden pilosa and its application in removing methylene blue from aqueous solutions DOI: 10.1016/j.heliyon.2023.e15766 -
Alkyl C-H confidence 1.0
“The collected cm-1, spectra from the paint surface showed bands at 2917 and 2849 corresponding to the cm-1 presence of long CH chains (CH stretching);”
Removal of a Past Varnish Treatment from a 19th-Century Belgian Wall Painting by Means of a Solvent-Loaded Double Network Hydrogel DOI: 10.3390/polym13162651 -
Alkyl C-H confidence 1.0
“The presence of peaks at cm-1 cm-1 2917 (sym) and 2842 (asym) confirmed the presence of aliphatic CH 2 cm-1 groups, and the band at 1464 is attributed to the deformation of the C=C bond.”
Algarra 等 - 2018 - Enhanced electrochemical response of carbon quantu DOI: 10.1016/j.talanta.2017.09.082
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