What absorbs at 1249 cm⁻¹ in an FTIR spectrum?
A band near 1249 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 1249 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 |
|---|---|---|---|
| C-O single bond | 8 | 8 | 1.0 |
| Methoxy (OCH3) | 7 | 7 | 1.0 |
| Methacrylate | 7 | 7 | 1.0 |
| Acetate | 7 | 7 | 1.0 |
| Amide | 5 | 4 | 1.0 |
| Secondary amine | 4 | 3 | 1.0 |
| C n single bond | 4 | 3 | 1.0 |
| Carbonyl (C=O) | 3 | 3 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Phenolic | 1 | 1 | 0.9 |
| Acetyl | 1 | 1 | 0.9 |
| C-S single bond | 1 | 1 | 0.9 |
| Sulfonyl | 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 |
|---|---|---|---|
| PVA | 1249, 1660, 2930 | Acetate, Methacrylate, C-O single bond | 1 |
| bacterial cellulose | 1249, 1050, 1631 | Methoxy (OCH3), Methacrylate, C-O single bond | 1 |
| GO | 1249, 1720, 1182 | Methacrylate, Acetate, 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 1249 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
-
Acetate confidence 1.0
“(1355 and C-O stretching (1249 It is noted that, the intensity of C-H and C-O-H bending significantly increased from 3.8% to 20.0% as presented in Fig.”
Solid polymer electrolyte production from 2-hydroxyethyl cellulose: Effect of NH4NO3 composition on its structural properties DOI: 10.1016/j.carbpol.2017.02.033 -
Carbohydrate confidence 1.0
“Absence cm-1 of hemicellulose in BC was indicated by disappearance of band at 1249 (Kubvosky, Kacikova, and”
In-situ Production and Collection of Bacterial Cellulose on Jute and Flax Mats by Static Cultivation DOI: 10.1080/15440478.2020.1870638 -
Acetate confidence 1.0
“A new absorption at around 1737 cm-1 C=O corresponded to stretching vibrations of esters, and the absorption at 1249 was assigned to C-O stretching vibration in carbonyl groups.”
Song 等 - 2020 - Acetylated Polysaccharides From Pleurotus geestera DOI: 10.3390/ijms21082810 -
Acetate confidence 1.0
“cm-1 Furthermore, peaks at about 1249 corresponds to the C-O stretching [12].”
Yusoff 等 - 2018 - Theoretical and Experimental Approach Towards P-Cy DOI: 10.1088/1757-899X/374/1/012086 -
Acetate confidence 1.0
“According to the FTIR spectra, GO shows the structure can be simplistically assumed in the form of O-H stretching at 3673.81 cm-1, C=O carboxyl stretching at 1750.02 cm-1, C=C stretching at 1664.93 cm-1, C-O epoxy group stretching at 1664.9”
Evaluation of Structural and Optical Properties of Graphene Oxide-Polyvinyl Alcohol Thin Film and Its Potential for Pesticide Detection Using an Optical Method DOI: 10.3390/photonics9050300 -
Acetate confidence 1.0
“1249 cm-1, due to the simple C-O diaryl bond and at 3285 2”
Georgescu 等 - 2021 - Thermal Behavior of the Nimesulide-Salicylic Acid DOI: 10.3390/ma14247715 -
Carbonyl (C=O) confidence 1.0
“cm-1 C-N to bonds, which extends to 1530 The band located at 1249 originates carbonyl groups (NH-CO-O) and ester carbonyl bonds (CO-O) at 1722 cm-1, along with from the amide group III (COOC) vibrations.”
Influence of Dimethacrylate Monomer on the Polymerization Efficacy of Resin-Based Dental Cements—FTIR Analysis DOI: 10.3390/polym14020247 -
Alkyl C-H confidence 1.0
“A sharp cm-1 and 1640 represents the presence of esters, cm-1 cm-1 peak at 1249 and 1100 shows the presence saturated aliphatic compounds and alkenes, respecof aliphatic amino compounds (C-N stretch).”
Masilamani 等 - 2023 - Characterization, Cytotoxicity and Anti-oxidant St DOI: 10.18502/ajmb.v15i3.12930
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