What absorbs at 3046 cm⁻¹ in an FTIR spectrum?
A band near 3046 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 4 cited sources
Quick answer
A band near 3046 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 |
|---|---|---|---|
| Aromatic ring | 3 | 3 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Alkene (C=C) | 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.
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 3046 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
“The bands at 3046 may be assigned to the OH group, while the cm-1 weak bands at 2978 and 2871 could be due to the C-H stretching vibrations which are”
Synthesis, crystal structures, quantum chemical studies and corrosion inhibition potentials of 4-(((4-ethylphenyl)imino)methyl)phenol and (E)-4-((naphthalen-2-ylimino) methyl) phenol Schiff bases DOI: 10.1016/j.molstruc.2017.06.104 -
Aromatic ring confidence 1.0
“The vibration frequencies at cm-1, 3046 and 2926 assigned to aromatic and aliphatic C(cid:21)H stretching, are diminished in PVK:PVDF-HfP.”
Alias 等 - 2015 - Optical Transition, Excitation, and Emission Prope DOI: 10.12693/APhysPolA.127.1430 -
Alkene (C=C) confidence 1.0
“β 2H g), 8.29, 8.27 (d, 2H f), 4.12-4.09 (t, 4H, to Ar-O-), 1,81 (m, 4H, to Ar-O-), 1.54 (m, γ 4H, to Ar-O-) 1,8-Bis[4-(naphthyliminomethylidene)-phenoxy]-octane cm-1): ν, FTIR (KBr, 3046 (=C-H stretch of the aromatic rings), 2941-2851 (C-H”
Mesomorphic Behavior of Symmetric Azomethine Dimers Containing Different Chromophore Groups DOI: 10.3390/molecules26082183 -
Aromatic ring confidence 0.9
“Explicit assignment in text: 'The aromatic stretching CH vibration wave numbers show up in the region 3046, 3035, 2996, 2994'”
Vibrational spectra, Hirshfeld surface analysis, molecular docking studies of (RS)-N,N-bis(2-chloroethyl)-1,3,2-oxazaphosphinan-2-amine 2-oxide by DFT approach DOI: 10.1016/j.heliyon.2020.e04641
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