What absorbs at 2884 cm⁻¹ in an FTIR spectrum?
A band near 2884 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 2884 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 | 10 | 8 | 1.0 |
| C-O single bond | 5 | 5 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 0.8 |
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 | 2884, 1650, 1655 | Alkyl C-H, Methacrylate, C-O single bond | 2 |
| hydroxyapatite | 2884, 1620, 1639 | Alkyl C-H, Methacrylate | 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 2884 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
“40% B + RF 20.145 19.246 0.015 70.00 cm(cid:3)1, acid.30 at 1350 and 1300 which also refers to the Cross50% B + RF 19.898 19.118 0.013 73.40 by linked structures are evident from the FT-IR spectra with Downloaded cm(cid:3)1, peaks at 2884 a”
Reticulated three-dimensional network ablative composites for heat shields in thermal protection systems DOI: 10.1039/c4ra05811a -
Hydroxyl (O-H) confidence 1.0
“3568.31 OH Stretching Hydroxyl group 3543.23 OH Stretching Hydroxyl group 2883.58 CH Stretching Methyne”
Spectral characterization of hydroxyapatite extracted from Black Sumatra and Fighting cock bone samples: A comparative analysis DOI: 10.1016/j.sjbs.2020.11.020 -
Acetate confidence 1.0
“absorption peak attributed to ether and acetal ring cm-1 (C-O-C) Two important vibrational bands at 2884 and 2839 of peaks produced during the cross-linking reaction of C-H”
Manesa 等 - 2022 - Fabrication and Characterization of Sericin-PVA Co DOI: 10.1021/acsomega.2c00897 -
Alkyl C-H confidence 1.0
“cm-1 cm-1 SM showed many intense peaks at 3324 for the acidic O-H, 2981 for the acidic showed many intense peaks at 3324 cm-1 for the acidic O-H, 2981 cm-1 for the acidic - cm-1 cm-1 -CH=CH- (aryl) str, 2884 for C-H (alkyl) str, 1635 for th”
Boosting the Anticancer Activity of Sunitinib Malate in Breast Cancer through Lipid Polymer Hybrid Nanoparticles Approach DOI: 10.3390/polym14122459 -
Alkyl C-H confidence 1.0
“H stretching band shifted to 3282 cm-1, indicating strong hydrogen bonding between plascm-1 cm-1 and 2884 (C-H symmetric stretching).”
Bugnotti 等 - 2023 - Structure of Starch-Sepiolite Bio-Nanocomposites DOI: 10.3390/polym15051207 -
Amide confidence 1.0
“In C-O, C-C, C-H (genipin) 3089, 1441, 721 2320 cm-1 addition, the C-N stretching of amide III at 1233 shifted to 1260 C-C, C-O, C-N (absorption 2884, 2683, 1952 1955, 1334, 1090, 924 cm-1 cm-1, after crosslinking with genipin, while the pe”
Delgadillo-Armendariz 等 - 2014 - INTERACTIONS OF CHITOSANGENIPIN HYDROGELS DURING DOI: 10.5935/0100-4042.20140243 -
Alkyl C-H confidence 1.0
“loaded CS NPs, the most dominant peaks were those corresponding to the polymeric loaded CS NPs, the most dominant peaks were those corresponding to the polymeric macm-1, matrix-carrier (CS), such as the peaks at 2884, 1641 and 1074 correspo”
L-Cysteine Modified Chitosan Nanoparticles and Carbon-Based Nanostructures for the Intranasal Delivery of Galantamine DOI: 10.3390/polym14194004 -
Acetate confidence 1.0
“The characteristic absorption modes observed in the FTIR spectrum at the wavenumbers ~732 , ~842, ~950, ~1048 , ~ 1113, ~ 1244 ,~ 1351,~ 1432, ~ 1468, ~2884 cm-1 6-), and ~2939 are attributed to C-Clst., 𝑠(PF (C-O-C)st., ν(COC) s,w(CH s, δ(”
Arya 等 - 2018 - Effect of variation of different nanofillers on st DOI: 10.1007/s11581-016-1784)
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