What absorbs at 1774 cm⁻¹ in an FTIR spectrum?
A band near 1774 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 1774 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) | 6 | 4 | 1.0 |
| Ester | 4 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| Imide | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
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 1774 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
“With time, the bands at 2138, most stable carbonyl band and the bands in the 1774cm(cid:2)1 2249cm(cid:2)1 region are evidently due to carbonyls on reduced chromium spedevelop, the band at de1902, 1794 and”
Influence of dealumination and treatments on the chromium speciation in zeolite CrBEA DOI: 10.1016/j.micromeso.2009.04.038 -
Acetate confidence 1.0
“The spectra of cm-1 cm-1 showed two strong characteristic absorptions at 1774 and 1709 which were related to cm-1 stretching vibration of C=O.”
Luan 等 - 2018 - Antioxidant Activity and Antifungal Activity of Ch DOI: 10.3390/polym10040395 -
Imide confidence 1.0
“The presence of strong characteristic peaks at 1774 and 1710 0 2 cm-1 3 are observed in chitosan/phthalic anhydride, corresponding to imide C=O stretching vibration.”
Mumtazah 等 - 2019 - Some properties of membrane based on chitosanphth DOI: 10.1063/1.5141679 -
Imide confidence 1.0
“From the PAI signature, the amide C=O region is observed around 1710 cm-1 and, at 1774 cm-1, Gels2023,9,619 11of25 the absorbance is associated with the imide carbonyl band, and the absorption band for cm-1.”
Pereira Dos Santos Lima 等 - 2023 - Thermal Evaluation of Silica-Based Insulated Magne DOI: 10.3390/gels9080619 -
Alkyl C-H confidence 1.0
“They cm-1, presented, respectively: (i) a dominant band at 1774 which was found to be systematically associated with cm-1 the presence of olivine (green star), (ii) aliphatics' vibration bands at 2850, 2920 and 2956 associated with cm-1 num”
Tracking hidden organic carbon in rocks using chemometrics and hyperspectral imaging DOI: 10.1038/s41598-018-20890-4 -
Carboxyl (COOH) confidence 1.0
“Particularly, the A u cm-1, phosphoric acid denatured collagen shows a broad band between 1774 and 1704 t h”
Dentin collagen denaturation status assessed by collagen hybridizing peptide and its effect on bio-stabilization of proanthocyanidins DOI: 10.1016/j.dental.2022.04.020. -
Ester confidence 0.9
“Explicit assignment: '1774 ... showing phthalate ester peak'”
Preparation of proton exchange membrane based on chitosan phthaloyl and chitosan blend for direct methanol fuel cell application DOI: 10.1063/1.5082482 -
Amide confidence 0.9
“Explicitly stated: protein amide I region, 1774-1576 cm-1.”
Using Synchrotron Radiation-Based Infrared Microspectroscopy to Reveal Microchemical Structure Characterization: Frost Damaged Wheat vs. Normal Wheat DOI: 10.3390/ijms140816706
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