What absorbs at 1781 cm⁻¹ in an FTIR spectrum?
Una banda cerca de 1781 cm⁻¹ puede apuntar a varios grupos funcionales. A continuación se muestran las asignaciones más probables, clasificadas por cuánta evidencia publicada respalda cada una — cada una trazable a literatura (DOI) y validada de forma cruzada con nuestros más de 130,000 espectros de referencia y grafo de conocimiento.
Backed by 4 cited sources
Quick answer
A band near 1781 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.
Posibles asignaciones de grupos funcionales
| Grupo funcional | Hechos de respaldo | Fuentes citadas | Confianza máxima |
|---|---|---|---|
| Carbonyl (C=O) | 4 | 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 |
| Alkyl C-H | 2 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
La clasificación refleja la evidencia acumulada de la literatura, no una única regla autorizada. Siempre confirme según el contexto de su muestra.
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 1781 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.
Literatura detrás de estas asignaciones
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Alkyl C-H confianza 1,0
“cm(cid:2)1) (up-shiing This GPEs 2964 CH asymmetrical stretching vibrations from 2937 2 cm(cid:2)1) C]O (up-shied 1789 stretching from 1866 Access cm(cid:2)1) C]O (down-shied 1772 stretching from 1781 cm(cid:2)1) (down-shied 1480 CH sci”
Electrocatalytic and structural properties and computational calculation of PAN-EC-PC-TPAI-I2 gel polymer electrolytes for dye sensitized solar cell application DOI: 10.1039/d1ra01983j -
Carbonyl (C=O) confianza 1,0
“3 cm-1 either EC or EMC from the electrolyte as evidenced by key new features at 1814 and 1781 cm-1 (comparable to the uc/c carbonyl stretching frequencies at 1807/1773 in free Gen2 cm-1 electrolyte) and prominent C(O)-O stretching modes at”
Pekarek 等 - 2020 - Intrinsic chemical reactivity of solid-electrolyte DOI: 10.1039/c9ta13535a -
Acetate confianza 1,0
“Comparing the ABS spectrum with the purified samples, it is possible to detect the appearance of three new absorbance peaks that are related to it is possible to detect the appearance of three new absorbance peaks that are related to the su”
Enhancing the Interface Behavior on Polycarbonate/Elastomeric Blends: Morphological, Structural, and Thermal Characterization DOI: 10.3390/polym15071773 -
Acetate confianza 1,0
“500 The most intense bands of iprodione are located at 1781 cm-1, and 998 which are due to C=O stretching and ring 400 breathing, respectively.”
Armenta 等 - 2007 - Determination of iprodione in agrochemicals by inf DOI: 10.1007/s00216-007-1152-z
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