What absorbs at 2841 cm⁻¹ in an FTIR spectrum?
A band near 2841 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 6 cited sources
Quick answer
A band near 2841 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 | 3 | 3 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| silica | 2841, 1100, 1080 | Alkyl C-H, Methacrylate | 2 |
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 2841 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
“hydroxyl groups of new generations, because in our experiments, cm(cid:1)1 cm(cid:1)1 2919 together withthe absorption at2841 is associated the thermal degradation was carried out in-situ to ensure the CeH with the stretching of saturated l”
Thermal ageing behavior of styrene-butadiene random copolymer: A study on the ageing mechanism and relaxation properties DOI: 10.1016/j.polymdegradstab.2012.06.015 -
Hydroxyl (O-H) confidence 1.0
“In fact, the peaks for PEICD contains stretching vibration (3563 article cm(cid:4)1), -C-H -P]O O H stretching (2841 bending vibration (2022 and and present in PHOS VES also appeared in the sym Article.”
Insight into carbon quantum dot–vesicles interactions: role of functional groups DOI: 10.1039/d1ra08809b -
Methoxy (OCH3) confidence 1.0
“The cm-1, band at 2841 associated to the methoxy group, which appeared upon mixing (Figure 3), disappears 5 for hydrolysis times of four hours (Figure 5A).”
El Hadad 等 - 2011 - Preparation of sol-gel hybrid materials from gamma DOI: 10.1007/s00396-011-2504-y -
Acetate confidence 1.0
“This suggests that the S metabolites extracted by at 1742 (C=O stretching), 2841 and 2920 (C-H”
Terrile 等 - 2016 - Chemometric Analysis of UV Characteristic Profile DOI: 10.5935/0103-5053.20160022 -
Alkyl C-H confidence 0.9
“Explicit assignment in text”
Comparative Analysis of Vegetable and Mineral Oil-Based Antiadhesive/Hydrophobic Liquids and Their Impact on Wood Properties DOI: 10.3390/ma16144975 -
Alkyl C-H confidence 0.6
“Text: '2841' (CH stretch implied)”
Lee 和 Ha - 2014 - Spectroscopic Analysis on Michael Addition Reactio DOI: 10.7317/pk.2014.38.2.257
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