What absorbs at 1445 cm⁻¹ in an FTIR spectrum?
A band near 1445 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
Quick answer
A band near 1445 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 |
|---|---|---|---|
| Alkyl C-H | 12 | 10 | 1.0 |
| Amide | 8 | 8 | 1.0 |
| Acetate | 7 | 6 | 1.0 |
| Methacrylate | 6 | 6 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| Aromatic ring | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Secondary amine | 4 | 4 | 1.0 |
| Nitrogen heterocycle | 4 | 4 | 1.0 |
| Lewis acid site | 4 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Alkene (C=C) | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Methyl | 2 | 2 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Isocyanate | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Bronsted acid site | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| Nanotubes | 1445, 1735, 1630 | Alkyl C-H, Methacrylate, Acetate | 1 |
| TiO2 | 1445, 1700, 1093 | Alkyl C-H, Methacrylate, Acetate | 1 |
| dentin | 1445, 575, 1740 | Amide, Methacrylate, Acetate | 1 |
Materials are shown only when the same literature pool supports this band and at least one additional characteristic peak.
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 1445 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
-
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Azmina 等 - 2012 - Preparation of Palm Oil Based Carbon Nanotubes at DOI: 10.4028/www.scientific.net/AMR.364.408 -
Protein confidence 1.0
“shows anincrease in collagen thata bandarearatio, 1665/1445 cm-1 Defining band area ratios content, while the decrease in the 1665/1445 changes in FTIR spectra of liquid samples is crucial to disfluids meanstheimpairedcollagendepositioninin”
The role of topically applied l-ascorbic acid in ex-vivo examination of burn-injured human skin DOI: 10.1016/j.saa.2017.05.055 -
confidence 1.0
“839, 1243, 1445, 1673 and 1726 The vibrational mode at the in-plane stretching and swinging of the N H, C H, and C O cm-1 cm-1 839 is derived from the out-of-plane swinging of the C O bonds.”
A comparative study on the experimental and calculated results of mid-infrared and Raman vibrational modes of nucleic acid bases DOI: 10.1016/j.jmgm.2017.04.016 -
Alkyl C-H confidence 1.0
“And bands identified at 1445 and 1500 were attributed to CH group.”
Yadav 等 - 2021 - Evaluation of tire derived rubber (TDR) fixed biof DOI: 10.1080/09593330.2020.1737736 -
confidence 1.0
“All the catalysts exhibited tained after pyridine adsorption on TiO dehydrated at 150 °C, then vacuum treated at cm-1 250 2 bands at 1445 and 1610 that correspond to the vibrations characteristic of pyridine ambient temperature and 150 °C,”
TiO2 Catalyzed Dihydroxyacetone (DHA) Conversion in Water: Evidence That This Model Reaction Probes Basicity in Addition to Acidity DOI: 10.3390/molecules27238172 -
Carbonate confidence 1.0
“The 1445 peak corresponds to the carbonate band (23).”
Abreu 等 - 2016 - Effect of Non-Thermal Argon Plasma on Bond Strengt DOI: 10.1590/0103-6440201600914 -
Acetate confidence 1.0
“cm-1 (stretching), 3065 due to = C-H (aromatic stretching), 2984 and 2950 due to C-H cm-1 cm-1 (stretching), 1696 due to C=O (stretching vibration), 1615 and 1488 due to C=C cm-1 cm-1 (ring stretching), 1445 due to CH3 (stretching), 1303 an”
Adam 等 - 2022 - Comparative Evaluation of Amlodipine Besylate Gene DOI: 10.14227/DT290422PGC2 -
Hydroxyl (O-H) confidence 1.0
“NH3 deformation in amino acids appeared at 1534 cm-1 and the band in 1445 cm-1 cm´1, can be associated with the in-plane -OH bending vibration in carboxylic acids.”
Biosorption of B-aflatoxins Using Biomasses Obtained from Formosa Firethorn [Pyracantha koidzumii (Hayata) Rehder] DOI: 10.3390/toxins8070218
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.