What absorbs at 1711 cm⁻¹ in an FTIR spectrum?
A band near 1711 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 1711 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) | 21 | 20 | 1.0 |
| Methacrylate | 15 | 14 | 1.0 |
| Acetate | 15 | 14 | 1.0 |
| Carboxyl (COOH) | 14 | 13 | 1.0 |
| Amide | 11 | 10 | 1.0 |
| Ester | 9 | 8 | 1.0 |
| Ketone | 8 | 7 | 1.0 |
| Methoxy (OCH3) | 7 | 7 | 1.0 |
| C-O single bond | 6 | 6 | 1.0 |
| Fatty acid | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Ring structure | 3 | 2 | 1.0 |
| Aromatic ring | 2 | 1 | 1.0 |
| Hydroxyl (O-H) | 2 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Protein random coil | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Thiol | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Carbonate | 1 | 0 | 1.0 |
| Silicon (Si) | 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 |
|---|---|---|---|
| polystyrene | 1711, 1020, 1600 | Methacrylate, Acetate, Carbonyl (C=O) | 1 |
| PMMA | 1711, 1722, 1383 | Methacrylate, Acetate, Carbonyl (C=O) | 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 1711 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
“In addition feasible by IR, for example when assessing the carbonyl stretch at 1711 (1), 1693 (2) and 1688 (3) m/z to the expected iminium base peak at 58, EI-MS displayed key ions at 173, 145, 125, 95, and 75.”
Analytical characterization of three trifluoromethylsubstituted methcathinone isomers DOI: 10.1002/dta.382 -
Alkyl C-H confidence 1.0
“[28] established a linear equation for (=C-H), cm-1 bands of virgin olive oil were seen at 1267 deformation in unconjugated cis double FFA determination in rapeseed and coconut oil by using the band of the FTIR spectra at 1711 cm-1 (C=C), c”
Monitoring Enzymatic Hydroesterification of Low-Cost Feedstocks by Fourier Transform InfraRed Spectroscopy DOI: 10.3390/catal9060535 -
Carboxyl (COOH) confidence 1.0
“The deconvolution of the carFrom the above discussion, it is clear that the cm(cid:3)1 bonyl band shows splitting of the peak into two peaks, peaks at 1711 and 1747 are due to the carboxylic cm(cid:3)1 cm(cid:3)1 cm(cid:3)1 one at 1736 comp”
Galgali 等 - 2007 - Sugar-linked biodegradable polymers Regio-specifi DOI: 10.1016/j.carbpol.2006.06.035 -
Acetate confidence 1.0
“1493.77 1487.98 C-H ring bend, O-CH 3 stretch 1710.74 1730.03”
Ganesan 等 - 2018 - The effect of titanium dioxide nano-filler on the DOI: 10.1007/s10854-018-8815-8 -
Carbonyl (C=O) confidence 1.0
“The EC-C spectrum showed a carbonyl stretch cm-1 peak at 1711 in resin coat, while an aromatic ring of benzene (C=C) was present in”
Structural, Physical, and Mechanical Analysis of ZnO and TiO2 Nanoparticle-Reinforced Self-Adhesive Coating Restorative Material DOI: 10.3390/ma14247507 -
Ester confidence 1.0
“Spectrum of TAX cc cm-1 shows prominent peaks at 1711,2516 and 1031 which is assigned to Ester (C = O) linkage, A -SH stretching and C-O-C bond.”
Ijaz 等 - 2019 - Thiolation of arabinoxylan and its application in DOI: 10.1080/03639045.2019.1569041 -
Carbonyl (C=O) confidence 1.0
“For the ester carbonyl funccm-1 178.11 ppm refer to the carbon atom of the carbonyl tional groups C=O of HYOOA at 1741 and the carcm-1, group (carboxylic acid) for MEOA and HYOOA, reboxylic carbonyl vibration functional group at 1711”
Salimon 等 - 2013 - Synthesis and optimization ring opening of monoepo DOI: 10.1186/2193-1801-2-429 -
Acetate confidence 1.0
“cm-1, PVAM-g-GT 1 h, the showed the peak for C=O stretching at 1643 N-H cm-1, cm-1 bending at 1543 C=O and C-O stretching at 1711 and 1227 that were assigned to the presence of carboxylic groups in the chemical structure.”
Green robust pH–temperature-sensitive maleated poly(vinyl alcohol)-g-gelatin for encapsulated capsaicin DOI: 10.1007/s00289-016-1609-3
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