What absorbs at 1587 cm⁻¹ in an FTIR spectrum?
A band near 1587 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 1587 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 | 10 | 10 | 1.0 |
| Ring structure | 6 | 6 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| C c single bond | 4 | 4 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| Urea | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Ammonium | 1 | 1 | 0.9 |
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 | 1587, 1650, 1655 | Alkyl C-H | 1 |
| polyethylene glycol | 1587, 1030, 1720 | Alkyl C-H, C c single bond | 1 |
| Polyamide | 1587, 1663, 1541 | Alkyl C-H | 1 |
| biomass | 1587, 1082, 1282 | Alkyl C-H, Aromatic ring | 1 |
| chitin | 1587, 1650, 1655 | Alkyl C-H | 1 |
| ZnO NPs | 1587, 1664, 875 | Alkyl C-H, C c single bond | 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 1587 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
-
Aromatic ring confidence 1.0
“LLM confirmed rule peak-group candidate”
Kim 等 - 2011 - Surface Functionality and Carbon Structures in Lig DOI: 10.1021/ef200915s -
Carboxyl (COOH) confidence 1.0
“In addition, bands, corresponding to cm-1) the stretching vibrations of carboxylate anion (1587 and 1414, 1412 appear.”
Kondratenko 等 - 2020 - Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dot DOI: 10.3390/ma13040909 -
Amide confidence 1.0
“cm-1 The characteristic peaks observed at 1650 and 1649 in both BSF and standard commercial chitosan were due to the presence of amide I (C=O) in the acetamide cm-1 group (NHCOCH 3), while the peaks observed at 1587 in both chitosan samples”
Antimicrobial Activity of Chemically and Biologically Treated Chitosan Prepared from Black Soldier Fly (Hermetia illucens) Pupal Shell Waste DOI: 10.3390/microorganisms9122417 -
Aromatic ring confidence 1.0
“Explicit assignment: 'The peak at 1587 cm-1 is due to an aromatic phenyl ring'”
Use of surface enhanced Raman spectroscopy for studying fouling on nanofiltration membrane DOI: 10.1016/j.seppur.2012.05.019 -
Acetate confidence 1.0
“There are two peaks at approximately 1587 and SSP 5.2 7.34 cm-1 1413 correspond to the asymmetric and symmetric W&H stretching vibrations of C=O and C-O in the acetate (COO) UDM 6.8 - 3.2 241 groups, respectively [38].”
Effect of polyethylene glycol and propyltrimethoxysilane on structural and optical properties of zinc oxide nanoparticles synthesized by sol–gel process DOI: 10.1007/s40094-018-0303-2 -
Amide confidence 1.0
“These bands are characteristic of different cm21), structures from amide I region (1649 and 1685 and cm21), b-turns a-helices amide II region: (1587 cross-peaks at 1670 vs.”
Structural analysis of some soluble elastins by means of FTIR and 2D IR correlation spectroscopy DOI: 10.1002/bip.21524 -
C c single bond confidence 1.0
“The aromatic compounds of ZnONPs are 1587.42cm-1 was withdrawn, and the final volume of the mixture was located at a peak value of identified using the C-C�C.”
Rajeshkumar 等 - 2022 - Degradation of Toxic Dye and Antimicrobial and Fre DOI: 10.1155/2022/4513208 -
Ring structure confidence 1.0
“FTIR peaks Peak assignments cm-1 ~ 1587, 1504, and 1488 Aromatic in-plane ring bend stretching vibration [20] Peaks assignable to polysulfone cm-1 1385-1365 C-H symmetric deformation vibration of >C(CH 3) [21] 2”
Tang 等 - 2009 - Effect of membrane chemistry and coating layer on DOI: 10.1016/j.desal.2008.04
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