What absorbs at 1161 cm⁻¹ in an FTIR spectrum?
A band near 1161 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 1161 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 |
|---|---|---|---|
| Methacrylate | 20 | 19 | 1.0 |
| Acetate | 20 | 19 | 1.0 |
| C-O single bond | 20 | 19 | 1.0 |
| Methoxy (OCH3) | 19 | 18 | 1.0 |
| Alkyl C-H | 8 | 7 | 1.0 |
| Carbohydrate | 6 | 6 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| N h | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Sulfonate | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Ring structure | 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 |
|---|---|---|---|
| cellulose nanocrystals | 1161, 1110, 1640 | Acetate, Methacrylate, C-O 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 1161 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
-
Ring structure confidence 1.0
“cm-1, due to Meanwhile, the presence of electron-withdrawing bromines in Meanwhile, the intense peaks at 1161 and 1042 υ(CCC) compound (2), reduced the electron density in the phenylene ring stretching vibration of long linear dioctyloxy ch”
Synthesis of a novel 1,4‐bis[2‐(5‐thiophen‐2‐yl)‐1‐benzothiophene]‐2,5‐dioctyloxybenzene pentamer for creatinine detection. DOI: 10.1002/ajoc.202100374 -
Acetate confidence 1.0
“1097 (w) C-O-C stretching in esters 1161 (m)”
Barnaby 等 - 2018 - Free Radical Scavenging Capacity, Carotenoid Conte DOI: 10.1155/2018/1762342 -
Acetate confidence 1.0
“Similarly, the bands at 1161, cm(cid:1)1 1079 and 1022 which are due to the C-O stretching mode of the C-OH groups”
Interactions between polyols and wheat biopolymers in a bread model system fortified with inulin: A Fourier transform infrared study DOI: 10.1016/j.heliyon.2018. -
confidence 1.0
“N(cid:1)(cid:1)H peaks observed at 1618.18 1626.86 At station 1, the presence of alkyl halides, C-F cm(cid:1)1 stretching was observed at 1161.19 these alkyl halides tend to be toxic, they deter predator in cm(cid:1)1 marine organisms [18].”
Sreenivasulu 等 - 2017 - Organic matter from benthic foraminifera (Ammonia DOI: 10.1016/j.mex.2017.01.001 -
Acetate confidence 1.0
“Meanwhile, the peak of 1160.83 is the fingerprint for stretching the C-O ester At the same time, cm-1 the peak of 813.54 represents the alkane group's fingerprints.”
Synthesis of magnetic nanocarbon using palm oil as the green precursor via microwave-assisted arc for wastewater treatment DOI: 10.1038/s41598-022-21982-y -
Carbohydrate confidence 1.0
“C-O bond stretching Pyranose ring 1161 Anti-symmetrical C-O-C stretching Cellulose 1105”
Micro-FTIR combined with curve fitting method to study cellulose crystallinity of developing cotton fibers DOI: 10.1007/s00216-020-03094-6 -
Acetate confidence 1.0
“However, a small peak at 1161 was attributed to the asymmetric C-O-C stretching vibrations associated with cellulose I and cm-1 cellulose II [52].”
Part A: Biodegradable Bio-Composite Film Reinforced with Cellulose Nanocrystals from Chaetomorpha linum into Thermoplastic Starch Matrices DOI: 10.3390/polym15061542 -
Alkyl C-H confidence 1.0
“test.However,thedisintegrationtimeforthesheabutterand 1176.33cm-1 1161.12cm-1, 719.71cm-1 to and to beeswax combination increased with increasing amounts of 718.71cm-1 which corresponds to C-H (CH 2), C-H (CH 3)”
Bartels 等 - 2021 - Formulation of Suppositories of Alum Produced from DOI: 10.1155/2021/6667562
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