What absorbs at 1268 cm⁻¹ in an FTIR spectrum?
A band near 1268 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
Resposta rápida
A band near 1268 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.
Possíveis atribuições de grupos funcionais
| Grupo funcional | Fatos de suporte | Fontes citadas | Maior confiança |
|---|---|---|---|
| Methacrylate | 8 | 7 | 1,0 |
| Acetate | 8 | 7 | 1,0 |
| Methoxy (OCH3) | 7 | 6 | 1,0 |
| C-O single bond | 7 | 6 | 1,0 |
| Amide | 3 | 3 | 1,0 |
| Ester | 3 | 2 | 1,0 |
| Carboxyl (COOH) | 3 | 2 | 1,0 |
| Carbonyl (C=O) | 3 | 2 | 1,0 |
| Ketone | 2 | 2 | 1,0 |
| Hydroxyl (O-H) | 2 | 2 | 1,0 |
| Lignin | 2 | 2 | 1,0 |
| Secondary amine | 1 | 1 | 1,0 |
| C n single bond | 1 | 1 | 1,0 |
| N h | 1 | 1 | 1,0 |
| Phosphate (PO4) | 1 | 1 | 1,0 |
| Alkyl C-H | 1 | 1 | 1,0 |
| C c single bond | 1 | 1 | 1,0 |
| Aromatic ring | 1 | 1 | 1,0 |
A classificação reflete a evidência acumulada da literatura, não uma única regra autoritária. Sempre confirme com o contexto da sua amostra.
Materiais possíveis
| Material | Picos de suporte | Grupos sobrepostos | Fontes citadas |
|---|---|---|---|
| chitosan | 1268, 1650, 1655 | Acetate, Methacrylate, C-O single bond | 1 |
| methacrylate | 1268, 873, 1725 | Methacrylate, Acetate, C-O single bond | 1 |
| lignin | 1268, 1035, 1510 | Methacrylate, Acetate, C-O single bond | 1 |
| wood | 1268, 1740, 1730 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| silver nanoparticles | 1268, 1636, 1631 | Methacrylate, Acetate, C-O single bond | 1 |
Os materiais são mostrados apenas quando o mesmo conjunto de literatura suporta esta banda e pelo menos um pico característico adicional.
Lógica do 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 1268 cm⁻¹ is usually not enough for material identification by itself.
Uso no mundo real
Este tipo de consulta é comum em identificação de polímeros, triagem de plásticos desconhecidos, solução de problemas de CQ, verificação de materiais reciclados e revisão de atribuição de picos apoiada pela literatura.
Erros comuns
- Tratar uma banda isolada como prova de um material sem verificar pelo menos um ou dois picos de suporte.
- Ignorando sobreposição: vários grupos funcionais podem contribuir próximo ao mesmo número de onda.
- Ignorar a validação quando aditivos, misturas, oxidação ou contaminação podem distorcer o espectro.
Conselho de verificação
Quando a ambiguidade persistir, valide a hipótese com DSC, GC-MS ou TGA, especialmente para misturas, amostras degradadas e polímeros carregados.
Literatura por trás destas atribuições
-
Acetate confiança 1,0
“The lignin specific FTIR peaks cm-1 noticed at 1268 , depicted the change in lignin's guaicyl ring plus C=O stretch.”
Majeed 等 - 2017 - Lignin macromolecule's implication in slowing the DOI: 10.1002/star.201600362 -
Acetate confiança 1,0
“Although hardwood lignin also contains guacm-1 (12) for syringyl ring and C-O stretch in lignin and iacyl moities, the absorption band at 1268 may have cm-1(13) cm-1.”
Pandey 和 Pitman - 2003 - FTIR studies of the changes in wood chemistry foll DOI: 10.1016/S0964-8305(03)00052-0 -
Acetate confiança 1,0
“The cm-1 peak 1507 could be attributed to an aromatic skeletal of lignin from lignocellulosic cm-1 materials and the medium band at 1268 is attributed to C-O stretching of phenol in lignite”
Optimization of primary sewage sludge and coal lignite by microwave assisted pyrolysis for the production of bio oil DOI: 10.1080/09593330.2020.1797903 -
C-O single bond confiança 1,0
“From the recent degraded sample (A') to the less aged one (B': 19th century), the cm-1 few changes concern the decrease in the intensity band at 1268 related to Car-O of ether group in guaiacyl monomer (methoxyl group branched to aromatic),”
Impact of Natural Degradation on the Aged Lignocellulose Fibers of Moroccan Cedar Softwood: Structural Elucidation by Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD) DOI: 10.3390/fermentation8120698 -
Acetate confiança 1,0
“1300-1320 C-O stretch doublet to lower wavenumbers at 1268 and 1245 cm-1 cm-1.”
Modelling ATR-FTIR Spectra of Dental Bonding Systems to Investigate Composition and Polymerisation Kinetics DOI: 10.3390/ma14040760 -
C c single bond confiança 1,0
“The three peaks appearing at 1268, 1390, cm-1 and 2925 are characteristic to C-C, C=C, and C-H stretching vibrations, respectively, proving the presence of alkyl and aryl groups [32,35].”
Fares 等 - 2021 - Influence of Nitrogen-Doped Carbon Dot and Silver DOI: 10.3390/chemosensors9030052 -
Phosphate (PO4) confiança 1,0
“(P-O-C or P-OH stretching), 1268”
Functionalization of poly(glycidylmethacrylate) with iminodiacetate and imino phosphonate groups for enhanced sorption of neodymium - sorption performance and molecular modeling DOI: 10.1016/j.reactfunctpolym.2022.105389 -
Acetate confiança 1,0
“and at 1268 due to cm-1 -C-O-C stretching.”
Kuen 等 - 2017 - Increased Loading, Efficacy and Sustained Release DOI: 10.3390/nano7110379
Tem um espectro com esta banda?
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