What absorbs at 1737 cm⁻¹ in an FTIR spectrum?
A band near 1737 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 1737 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 |
|---|---|---|---|
| Carbonyl (C=O) | 40 | 33 | 1.0 |
| Carboxyl (COOH) | 26 | 23 | 1.0 |
| Ester | 23 | 21 | 1.0 |
| Acetate | 23 | 21 | 1.0 |
| Methacrylate | 22 | 20 | 1.0 |
| Ketone | 20 | 18 | 1.0 |
| Amide | 20 | 18 | 1.0 |
| Lipid | 6 | 5 | 1.0 |
| Lignin | 4 | 4 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| Acetyl | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 0 | 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 | 1737, 1735, 1650 | Acetate | 1 |
| hemicellulose | 1737, 1730, 897 | Acetate, Carbonyl (C=O) | 1 |
| GO | 1737, 1720, 1182 | Acetate, Carboxyl (COOH) | 1 |
| rGO | 1737, 2358, 2930 | Acetate | 1 |
| PCL | 1737, 1751, 1724 | Acetate, Carbonyl (C=O) | 1 |
| Polyvinyl Alcohol | 1737, 1141, 1640 | Acetate, Carbonyl (C=O), Carboxyl (COOH) | 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 1737 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
-
Carbonyl (C=O) confidence 1.0
“cm-1 In all spectra of samples C0-C3, the peak that appear at ~1640 can be assigned to cm-1 C=C and corresponded to the bonded carbonyl groups, and the peak at 1737 related to the free carbonyl groups [40-42].”
Study of Polyvinyl Alcohol-SiO2 Nanoparticles Polymeric Membrane in Wastewater Treatment Containing Zinc Ions DOI: 10.3390/polym13111875 -
Acetate confidence 1.0
“hydrogen bonded hydroxyl groups (3600-3200 cm-1 The standard has a very strong band at 1737 that is assigned to C=O cm-1 that corresponds to in-plane stretching of COOH group and a band at 1229 bending vibrations of OH groups from COOH (Fig”
Miletic 等 - 2020 - Oxidized humic acids from the soil of heat power p DOI: 10.2298/JSC190726099M -
Carboxyl (COOH) confidence 1.0
“LLM confirmed rule peak-group candidate”
Okuno 等 - 2003 - FTIR detection of protonationdeprotonation of key DOI: 10.1021/ja021302z -
Carbonyl (C=O) confidence 1.0
“cm-1 A new peak at 1737 corresponding to thealdehyde group of carbonyl compound was observed inglycated-HSA.”
Raghav 等 - 2017 - Nonenzymatic glycosylation of human serum albumin DOI: 10.1371/journal. -
Carboxyl (COOH) confidence 1.0
“MWCNT with HA, there is a dramatic varation in the peaks corresponding to the oxygen functionalities, such as the -COOH stretching vibration peak at 1737 cm-1 and the -OH deformation vibration peaks (3425 cm-1 and 1400 cm-1) of carboxylic g”
Novel synthesis of bioactive hydroxyapatite/f-multiwalled carbon nanotube composite coating on 316L SS implant for substantial corrosion resistance and antibacterial activity DOI: 10.1016/j.jallcom.2018.10.341 -
Ester 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 -
Lipid confidence 1.0
“1a, the intensity of the epoxy 44 cm-1 markers is really low (the slight increase observed at the 1737 band is related to the 45 decrease of shellac wax concentration because of epoxy penetration).”
Beltran 等 - 2015 - Optimal Sample Preparation for the Analysis of Mic DOI: 10.1021/acs.analchem.5b01997 -
Carbonyl (C=O) confidence 1.0
“The strong cm-1 cm-1 band at 1737 due to carbonyl (C=O) and at 1170 assigned to C-O-C stretching”
Characterization of Waxes in the Roman Wall Paintings of the Herculaneum Site (Italy) DOI: 10.3390/app122111264
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