What absorbs at 1591 cm⁻¹ in an FTIR spectrum?
A band near 1591 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 1591 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 | 6 | 5 | 1.0 |
| Amide | 6 | 5 | 1.0 |
| Alkene (C=C) | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 1 | 1.0 |
| N h | 2 | 1 | 1.0 |
| Quinone | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 0.9 |
| Secondary amine | 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 |
|---|---|---|---|
| chitosan | 1591, 1650, 1655 | Amide, Methoxy (OCH3) | 1 |
| alginate | 1591, 1100, 1715 | Methoxy (OCH3), Amide | 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 1591 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
-
confidence 1.0
“to 1573 The highest conducting sample contains 50 wt% of NH 4CF 3SO amine peak at 1591 × 10-7 cm-1.”
Characterizations of chitosan-ammonium triflate (NH4CF3SO3) complexes by FTIR and impedance spectroscopy DOI: 10.1002/pssa.200521016 -
Acetate confidence 1.0
“The peaks at 1591 and 1411 correspond and symmetric stretching vibrations of the C-O bond of the COOgroup, respectively to the asymmetric and symmetric stretching vibrations of the C-O bond of the COO- [36-38].”
Kim 等 - 2022 - Removal of Methyl Red from Aqueous Solution Using DOI: 10.3390/ijerph19159030 -
Aromatic ring confidence 1.0
“1591cm-1 The benzene ring C=C stretching vibration absorption peaks located at and 2994”
Li 等 - 2011 - The detection of Cypermethrin on the surface of Ap DOI: 10.4028/www.scientific.net/AMR.287-290.2991 -
Amide confidence 1.0
“The new peak at 1591 in acid equilibrated DHOA was assigned to the amide carbonyl”
Verma 等 - 2018 - Structural investigations on uranium(VI) and thori DOI: 10.1039/C7NJ04460G. -
Acetate confidence 1.0
“cm-1 cm-1 at the wave number 3468 Meanwhile of figure 2 (c) wavenumbers 1591 and 1288 show absorption of functional groups C = C and C - O as indicated by activated carbon/10wt% rGO.”
Wardani 等 - 2020 - Analysis of ChargingDischarging Supercapacitor Ac DOI: 10.1088/1742-6596/1491/1/012044 -
Alkene (C=C) confidence 1.0
“The C=C stretching mode of the quinoid ring appeared at 1591 cm-1, which was attributed to the stretching vibration of the o-meth-”
Synthesis, Characterization, and Antibacterial Potential of Poly(o-anisidine)/BaSO4 Nanocomposites with Enhanced Electrical Conductivity DOI: 10.3390/pr10091878 -
Amide confidence 1.0
“cm-1 cm-1 represent the aliphatic C-H stretching, 1651 is due to C Upon freeze drying procedure, the morphological details of the cm-1 = O stretching of the amide I, 1591 is the bending vibration microspheres are presented in Fig.”
Preparation, structural characterisation and release study of novel hybrid microspheres entrapping nanoselenium, produced by green synthesis DOI: 10.1049/iet-nbt.2016.0107 -
Alkyl C-H confidence 1.0
“cm1 and 1056 The bands at 1591 and 1583 can be attributed to -O-CH 2OH from the partly oxidised methanol”
Towards Methane Combustion Mechanism on Metal Oxides Supported Catalysts: Ceria Supported Palladium Catalysts DOI: 10.1007/s11244-019-01143-8
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