What absorbs at 1691 cm⁻¹ in an FTIR spectrum?
Una banda cerca de 1691 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 8 cited sources
Respuesta rápida
A band near 1691 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 |
|---|---|---|---|
| Amide | 10 | 8 | 1,0 |
| Carbonyl (C=O) | 7 | 6 | 1,0 |
| Methacrylate | 6 | 6 | 1,0 |
| Acetate | 6 | 6 | 1,0 |
| Ketone | 5 | 5 | 1,0 |
| Ester | 5 | 5 | 1,0 |
| Carboxyl (COOH) | 5 | 5 | 1,0 |
| Protein beta sheet | 2 | 2 | 1,0 |
| Protein | 2 | 2 | 1,0 |
| Alkene (C=C) | 1 | 1 | 1,0 |
| Methoxy (OCH3) | 1 | 1 | 1,0 |
| C-O single bond | 1 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
| C c single bond | 1 | 1 | 1,0 |
| C=n | 1 | 1 | 1,0 |
| Water (H2O) | 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.
Lógica de espectro
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 1691 cm⁻¹ is usually not enough for material identification by itself.
Uso en el mundo real
Este tipo de consulta es común en la identificación de polímeros, cribado de plásticos desconocidos, resolución de problemas de control de calidad, verificación de materiales reciclados y revisión de asignación de picos respaldada por la literatura.
Errores comunes
- Tratar una banda aislada como prueba de un material sin verificar al menos uno o dos picos de apoyo.
- Ignorando superposición: múltiples grupos funcionales pueden contribuir cerca del mismo número de onda.
- Omitir la validación cuando los aditivos, las mezclas, la oxidación o la contaminación puedan distorsionar el espectro.
Consejo de verificación
Cuando persista la ambigüedad, valide la hipótesis con DSC, GC-MS o TGA, especialmente para mezclas, muestras degradadas y polímeros rellenos.
Literatura detrás de estas asignaciones
-
Water (H2O) confianza 1,0
“This side chain is increased, allowing water molecules to fully solvate the D-ringcarbonylandshiftingthevibrationalfrequencyto1691cm-1.”
Chenchiliyan 等 - 2023 - Ground-state heterogeneity and vibrational energy DOI: 10.1063/5.0135268 -
Protein confianza 1,0
“(1656cm(cid:2)1), a-helix b-sheet and Krimm [20] observed that The thyroid spectra, in addition to evident strong protein peaks 1691cm(cid:2)1) (1647cm(cid:2)1) (1626, 1679, and unordered secondary cm(cid:2)1 1659cm(cid:2)1, at 1547 and als”
Das 等 - 2008 - FTIR of touch imprint cytology A novel tissue dia DOI: 10.1016/j.jphotobiol.2008.05.012 -
Protein confianza 1,0
“Another peak at 1691 was likely (cid:2)-sheet indicative of a structure formed by unfolding and aggreof the protein via lyophilization [44].”
Additives affecting thermal stability of salmon calcitonin in aqueous solution and structural similarity in lyophilized solid form DOI: 10.1016/j.procbio.2011.08.017 -
C=n confianza 1,0
“The C=N stretching frequency of free aminoguanidine cm-1, bicarbonate is known to occur at 1691 and a peak was observed in the complexes at cm-1, 1650 indicating that the imine nitrogen atom is involved in the complexation.”
Synthesis and Crystal Structure of [Ni(Amgu)2]X2 – Novel Solid-State Precursors for NiO Nanoparticles DOI: 10.1016/j.ica.2018.07.021 -
C c single bond confianza 1,0
“weak C-H stretching at 3.86.05 3810.57 3859.98 We further observed sharp asymmetric C = O cm-1, cm-1 carboxylate at 1691.28 C-C ring stretching at 1419.30 and C-N stretching of a tertiary amine at cm-1.”
Characterizing and demonstrating the role of Klebsiella SSN1 exopolysaccharide in osmotic stress tolerance using neutron radiography DOI: 10.1038/s41598-023-37133-w -
Acetate confianza 1,0
“cm-1 The narrow peak at 1691 fits chiefly to C=O stretching.”
Influence of gamma irradiation on rosin properties and its antimicrobial activity DOI: 10.1038/s41598-023-31372-7 -
Acetate confianza 1,0
“Based on the study of the FTIR spectrum of cm-1, the FTIR spectrum of DMPA, the C=O absorption peak of DMPA is located at 1691 which DMPA, the C=O absorption peak of DMPA is located at 1691 cm-1, which proves that the prepolymers”
Synthesis of Linseed Oil-Based Waterborne Urethane Oil Wood Coatings DOI: 10.3390/polym10111235 -
Amide confianza 1,0
“1940.31 - 1999.62,1951.55 1905.70 Allene Results concerning the banana peels derived activated carbon were stretching) similar to those reported by Zheng and Wang [34], whereas some peaks - 1690.75 - - Primary amide (C--O stretching) were i”
Preparation and characterization of activated carbon from agricultural wastes and their ability to remove chlorpyrifos from water DOI: 10.1016/j.toxrep.2023.01.011
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