What absorbs at 1781 cm⁻¹ in an FTIR spectrum?
A band near 1781 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 4 cited sources
Réponse rapide
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.
Attributions possibles de groupes fonctionnels
| Groupe fonctionnel | Faits à l＇appui | Sources citées | Confiance maximale |
|---|---|---|---|
| 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 |
Le classement reflète les preuves bibliographiques accumulées, et non une règle faisant autorité. Confirmez toujours dans le contexte de votre échantillon.
Logique du spectre
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.
Utilisation réelle
Ce type de requête est courant dans l＇identification des polymères, le criblage des plastiques inconnus, le dépannage du contrôle qualité, la vérification des matériaux recyclés et l＇examen de l＇attribution des pics appuyée par la littérature.
Erreurs courantes
- Traiter une bande isolée comme preuve d＇un matériau sans vérifier au moins un ou deux pics de support.
- Ignorer le chevauchement : plusieurs groupes fonctionnels peuvent contribuer près du même nombre d＇onde.
- Sauter la validation lorsque des additifs, des mélanges, l＇oxydation ou la contamination peuvent déformer le spectre.
Conseil de vérification
Lorsque l＇ambiguïté persiste, validez l＇hypothèse avec DSC, GC-MS ou TGA, en particulier pour les mélanges, les échantillons dégradés et les polymères chargés.
Bibliographie derrière ces attributions
-
Alkyl C-H confiance 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) confiance 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 confiance 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 confiance 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
Avez-vous un spectre avec cette bande ?
Téléchargez votre spectre FTIR et obtenez un rapport d＇interprétation complet — attributions de pics avec citations bibliographiques, correspondances de bibliothèque et une chaîne de preuves avec évaluation de la confiance — en quelques secondes.