What absorbs at 1766 cm⁻¹ in an FTIR spectrum?
A band near 1766 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 4 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Carbonyl (C=O) | 3 | 3 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Carbonyl (C=O) confidence 1.0
“FTIR peaks of cm-1 ZnO-PMMA nanocomposite thin films were observed at 540 for Zn-O bond and at 1766 cm-1 for ester carbonyl C=O stretch vibration of PMMA.”
Carrier mechanism of ZnO nanoparticles-embedded PMMA nanocomposite organic bistable memory device DOI: 10.1016/j.solidstatesciences.2019.106046 -
Acetate confidence 1.0
“Other strong Raman features are the D and G bands of C-C bonds between cm-1 cm-1, 1300 and 1700 and a weak band observed at ~1766 assigned to C=O stretching in acetylated polysaccharides.”
High-Content Aloe vera Based Hydrogels: Physicochemical and Pharmaceutical Properties DOI: 10.3390/polym15051312 -
Carbonyl (C=O) confidence 1.0
“1684 1679 C=O carbonyl stretching vibration (intensity less) 1766 1760 1745”
Rangel-Vazquez 等 - 2014 - Spectroscopy Analyses of PolyurethanePolyaniline DOI: 10.1590/0104-1428.1496 -
Aromatic ring confidence 1.0
“cm-1, a peak obtained at 1766 which shows the stretching vibration of aromatic C=C bonds (Guerrero-Contreras & properties were evaluated after ageing, and percentage retention of these properties was calculated according to equation 1.”
Sampath 等 - 2022 - Synthesis of polyethylene glycol-grafted graphite DOI: 10.4038/jnsfsr.v50i4.10902
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 confidence-rated evidence chain — in seconds.
Interpret my spectrum