What absorbs at 2937 cm⁻¹ in an FTIR spectrum?
A band near 2937 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 2937 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 | 20 | 17 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 0.8 |
| N h | 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 |
|---|---|---|---|
| silica | 2937, 1100, 1080 | Silicon-oxygen (Si-O), Silicon (Si), Alkyl C-H | 1 |
| polysaccharide | 2937, 1637, 1320 | Alkyl C-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 2937 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
“10 shows XRD peak 2937 for CH asymmetrical stretching vibrations 2 cm(cid:2)1, downshis pattern of PAN-EC-PC-xTPAI-I from 2964 1485 for CH scissoring/CH GPEs where x stands for 10%, 2”
Electrocatalytic and structural properties and computational calculation of PAN-EC-PC-TPAI-I2 gel polymer electrolytes for dye sensitized solar cell application DOI: 10.1039/d1ra01983j -
confidence 1.0
“NMR spectrum gave sigmaterial by FTIR showed bands at 2937 and -108, -99, -68 -59ppm, Q4, Q3, T4 T2 nals at and and species related to the silica backbone structure.”
Dey 等 - 2008 - Mesoporous silica functionalized with diethylenetr DOI: 10.1016/j.colsurfa.2008.03.030 -
Alkyl C-H confidence 1.0
“The 2 cm.-1 cm-1 O-H stretching is seen at 3330 The peak at 2937 is observed due to methylene C-H cm-1 stretching at the PAN segments of AVA Np4.”
Synthesis of Aloevera/Acrylonitrile based Nanoparticles for targeted drug delivery of 5-Aminosalicylic acid DOI: 10.1016/j.ijbiomac.2017.08.085 -
Alkyl C-H confidence 1.0
“Calorimetric studies of prepared in-situ gel were performed by taking 4-5 mg sample and placing FTIR spectra of PVA showed stretching band of cm-1 3250cm-1 it in hermetically sealed aluminium pans and 2937.1 for alkyl stretching, and scanni”
Anuml 等 - 2021 - Development and characterization of ceftriaxone in DOI: 10.4314/tjpr.v20i4.2 -
Alkyl C-H confidence 1.0
“4) were present, which conevidenced by the strong, broad, overlapping C-H stretching 2937cm-1, firmed the quartz sand served as a suitable inert mineral matrix.”
Gordon 和 Sephton - 2016 - Organic Matter Detection on Mars by Pyrolysis-FTIR DOI: 10.1089/ast.2016.1485 -
Hydroxyl (O-H) confidence 1.0
“The strong absorptions cm-1 cm-1 and 2937 were assigned for O-H (alcoat 3400 hol) or N-H (amines) stretching vibration and C-H (alkyl) cm-1 stretching.”
Application of mycogenic silver/silver oxide nanoparticles in electrochemical glucose sensing; alongside their catalytic and antimicrobial activity DOI: 10.1007/s13205-021-02888-4 -
Alkyl C-H confidence 1.0
“Notably, spectral patterns of C-H cm-1 differences vibration around 2937 show remarkable between HWGA-SA and LWGA-SA;”
Jeong 等 - 2019 - Gelatin-Alginate Complexes for EGF Encapsulation DOI: 10.3390/pharmaceutics11100530 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Effect of Repeated Contact to Food Simulants on the Chemical and Functional Properties of Nano ZnO Composited LDPE Films for Reusable Food Packaging DOI: 10.3390/polym15010009
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