What absorbs at 1874 cm⁻¹ in an FTIR spectrum?
A band near 1874 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 2 cited sources
Quick answer
A band near 1874 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 |
|---|---|---|---|
| Amide | 3 | 2 | 1.0 |
| Methacrylate | 2 | 1 | 1.0 |
| Ketone | 2 | 1 | 1.0 |
| Ester | 2 | 1 | 1.0 |
| Carboxyl (COOH) | 2 | 1 | 1.0 |
| Carbonyl (C=O) | 2 | 1 | 1.0 |
| Acetate | 2 | 1 | 1.0 |
| Ammonium | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
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 1874 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
-
Amide confidence 1.0
“The intensive bands located at 1874, 1567 and 1056 were peared after being treated with sodium sulfide and were assigned to the stretching vibraC-O, C-N correlated with the and C=S groups, as shown in Figure 5b [16,17].”
Ibrahim 等 - 2022 - Effect of Ammonium Sulfide on Sulfidization Flotat DOI: 10.3390/min12101193 -
Acetate confidence 1.0
“(the ((cid:1874)) of the C=O band) in amide and 1737 cm-1 stretching vibration of the lipid [22], (3) (the 1467 cm-1 (the CH3 bending of the lipid or protein regions) [11], and (4) 1087 and 1241 cm-1 ((cid:1874) as)”
Srisongkram 等 - 2020 - Evaluation of Melanoma (SK-MEL-2) Cell Growth betw DOI: 10.3390/ijms21114141
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