What absorbs at 1601 cm⁻¹ in an FTIR spectrum?
A band near 1601 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 1601 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 | 11 | 10 | 1.0 |
| Alkyl C-H | 7 | 7 | 1.0 |
| Alkene (C=C) | 7 | 7 | 1.0 |
| Ring structure | 6 | 6 | 1.0 |
| Carboxyl (COOH) | 5 | 5 | 1.0 |
| N h | 5 | 3 | 1.0 |
| Carbonyl (C=O) | 4 | 4 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| C c single bond | 4 | 4 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Amine primary | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Thiocarbonyl | 1 | 1 | 1.0 |
| Styrene | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 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 |
|---|---|---|---|
| polystyrene | 1601, 1020, 1600 | Aromatic ring, Alkyl C-H | 1 |
| bitumen | 1601, 1625, 810 | Alkyl C-H, Aromatic ring | 1 |
| polyaniline | 1601, 1565, 1570 | Aromatic ring, Alkyl C-H, Ring structure | 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 1601 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
“cm(cid:3)1, A nitration peak was noted at 1601 which corresponds to N-H bending.”
Effect of used motor oil as a rejuvenator on crumb rubber modifier’s released components to asphalt binder DOI: 10.1177/1477760620918600 -
Aromatic ring confidence 1.0
“The peak at 1600.63 cm-1 is attributed to the bond in benzene with strong to weak intensity.”
Preparation and Characterization of Sound-Absorbent Based on Polystyrene Reinforced Primary Sludge and Fly Ash from Pulp Mill DOI: 10.14716/ijtech.v14i3.5131 -
confidence 1.0
“In NI-Pro-MNF stretching vibration peaks at 1600.9 (C=O), 3336 (N-H) and cm-1 at 1090.2 corresponds to the pyrrolidine ring's N-H in a twisting and rocking vibrations are the evidence of complex formation of metal ions with complexing agent”
A novel study for producing complexed and encapsulated nutrients at nanometric scale to enhance plant growth DOI: 10.1038/s41598-023-37607-x -
Carbonyl (C=O) confidence 1.0
“Although 253 this range was used by several studies as a reference peak [13], it can cause errors due to its high 254 1601cm-1 absorption percentage compared to the carbonyl.”
Omairey 等 - 2019 - Impact of anti-ageing compounds on oxidation agein DOI: 10.1016/j.conbuildmat.2019.07.021 -
Metal oxygen confidence 1.0
“cm-1 stretching59 cm-1 at 3434 In graph (d), main peak at 513 is assigned to Cu-O while peak at 1601 is”
Antibacterial and in vivo toxicological studies of Bi2O3/CuO/GO nanocomposite synthesized via cost effective methods DOI: 10.1038/s41598-022-17332-7 -
Aromatic ring confidence 1.0
“Vibrations located at 1601 1514 and cm-1 cm-1 that formic acid can assist the catalyst of (Ni-W) 20/ZrP in the 1460 and 650 are attributed to aromatic ring.”
Effective depolymerization of alkali lignin into phenolic monomers over ZrP catalysts promoted by Ni and W DOI: 10.1007/s13399-021-01594-8 -
C c single bond confidence 1.0
“Specifically, after TFOT aging, the Sa and Sq as shown in Tables 9 and 10 values of SBS modified asphalt increase by 6.5% and 7% respectively, cm(cid:0) -C-- -C-- 1 The Cabsorption peak at 1601 is attributed to the Cboth of which are smalle”
Low-temperature characteristics and microstructure of asphalt under complex aging conditions DOI: 10.1016/j.conbuildmat.2021.124408 -
Acetate confidence 1.0
“attached to the aromatic graphene network at 1409 the C-O (hydroxyl) stretching at 1601 cm-1 cm-1 the C-O (epoxy) stretching at 1040 and the C-O (phenolic) stretching at 1213 [18,30].”
Preparation of Electrospun Nanocomposite Nanofibers of Polyaniline/Poly(methyl methacrylate) with Amino-Functionalized Graphene DOI: 10.3390/polym9090453
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.