What absorbs at 2858 cm⁻¹ in an FTIR spectrum?
A band near 2858 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 2858 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 | 12 | 12 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 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 |
|---|---|---|---|
| silica | 2858, 1100, 1080 | Alkyl C-H, Methacrylate, Acetate | 1 |
| biomass | 2858, 1082, 1282 | Alkyl C-H, Methacrylate, Acetate | 1 |
| polyurethane | 2858, 2270, 1700 | 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 2858 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
“vibration is identified at 3471 The characteristic peaks of C-H stretching and cm-1, anti-symmetric stretching vibrations are assigned at 2858 and 2943 respeccm-1 cm-1 tively.”
Thermal degradation and crystallization kinetics studies on synthesized calcium mercaptosuccinate end-capped poly(ε-caprolactone) nanocomposite DOI: 10.1007/s00289-018-2614-5 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
A Parametric Study on a Diesel Engine Fuelled Using Waste Cooking Oil Blended with Al2O3 Nanoparticle—Performance, Emission, and Combustion Characteristics DOI: 10.3390/su13137195 -
Alkyl C-H confidence 1.0
“In particular, the characteristic peaks at 3349 cm-1 for N-H bonds, 3070 cm-1 for alkene C-H bonds, and 2858 and 2538 cm-1 for alkane C-H bonds became gradually apparent when the temperature was above 110 °C (Figure 10b).”
Synthesis and Characterization of Linear Polyisoprene Supramolecular Elastomers Based on Quadruple Hydrogen Bonding DOI: 10.3390/polym12010110 -
Alkyl C-H confidence 1.0
“The ν(C-H)asym (at 2936 cm-1) band shows positive correlation peaks, while the ν(C-H)sym (at 2858 cm-1) band exhibits negative ones (Figure 5a).”
Drzewicz 等 - 2020 - Vibrational Dynamics of a Chiral Smectic Liquid Cr DOI: 10.3390/cryst10080655 -
Alkyl C-H confidence 1.0
“cm-1 cm-1) In fact, the appearance of additional bands (2858 and 2929 can be as- (-CH signed to the representative groups of DDA: asymmetric stretching vibrations 2) and (-CH symmetric 2) vibrations of the methylene groups, respectively [43”
Efficient Adsorption of Chromium Ions from Aqueous Solutions by Plant-Derived Silica DOI: 10.3390/molecules27134171 -
Alkyl C-H confidence 1.0
“cm(cid:3)1,28,35,36 composites.35,38 at 3427 asymmetric CH stretching at 2938 Thus, the NCO intensity decreases with the 2 cm(cid:3)1,28,35 cm(cid:3)1,35,37 O-CH March increase in the BG amount because of the formation of PU and symmetric C”
Polyurethane/58S bioglass nanofibers: synthesis, characterization, and in vitro evaluation DOI: 10.1039/c5ra24786a -
Alkyl C-H confidence 1.0
“near doublets is indicative of a loss of the crystal structure of In total reflection mode, all acquired mid-IR spectra hydrocarbon chains during the bulk sample preparation (Figure 3) exhibit sharp maxima of the CH2 stretching bands 2858cm”
Invernizzi 等 - 2018 - Mid and Near-Infrared Reflection Spectral Database DOI: 10.1155/2018/7823248 -
Alkyl C-H confidence 1.0
“FTIR Analysis 2925cm-1, 2858cm-1 1416cm-1 The bands around and can be ascribed to the C-H vibration of the organics.”
Latha 等 - 2017 - Effect of Capping Agent on the Morphology, Size an DOI: 10.1590/1980-5373-MR-2016-0292
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