What absorbs at 2859 cm⁻¹ in an FTIR spectrum?
A band near 2859 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 2859 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 | 5 | 5 | 1.0 |
| Hydrogen bond | 3 | 3 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| N n bond | 1 | 1 | 1.0 |
| Thiol | 1 | 1 | 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 |
|---|---|---|---|
| polyethylene | 2859, 1737, 1720 | Alkyl C-H, Aromatic ring | 1 |
| saliva | 2859, 1648, 1664 | Alkyl C-H | 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 2859 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
-
Thiol confidence 1.0
“CH symmetric stretch: 2859.1 S-H stretch: 2936.2 2”
Elkins - 2011 - Rapid Presumptive Fingerprinting of Body Fluids DOI: 10.1111/j.1556-4029.2011.01870.x -
N n bond confidence 1.0
“ν n n X Next, the absorption profiles of the 2859, 2962 band, and (1) α(ν3)”
Miyamoto 等 - 2012 - Cluster size resolving analysis of CH3F-(ortho-H-2 DOI: 10.1063/1.4765698 -
Alkyl C-H confidence 1.0
“cm-1), stretched.37 observed for the CH asymmetric stretching (at 2918 2 cm-1), G adsorption was observed by a gradual increase in the CH symmetric stretching (2859 and CH symmetric 4 2 3 cm-1).”
Ciumac 等 - 2017 - Influence of Acyl Chain Saturation on the Membrane DOI: 10.1021/acsomega.7b01270 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Technological and Functional Approaches Applied to Miniature Vessels with Pigment Traces: Two Middle Bronze Age Case Studies from Eastern Subcarpathians of Romania DOI: 10.3390/app13042093 -
Amide confidence 1.0
“- - - 2851-2860 CH methylene symmetric stretching 2859 2862 2859 C]O - 1632-1660 stretching amide I 1633 1633 1633 1633 1631 3.0 C-N”
Facile synthesis of novel calcium silicate hydrated-nylon 6/66 nanocomposites by solution mixing method DOI: 10.1039/c8ra07116k -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Evaluation of Physico-Mechanical Properties on Oil Extracted Ground Coffee Waste Reinforced Polyethylene Composite DOI: 10.3390/polym14214678 -
Aromatic ring confidence 1.0
“Mahadik Department of Chemistry, Charitrakar -C-H 2858.83 for aromatic stretching, 1671.60 cm-1 Padma Bhushan Dr.”
Manjare 等 - 2023 - Microwave-Assisted Rapid and Green Synthesis of Sc DOI: 10.1021/acsomega.2c05187 -
Alkyl C-H confidence 1.0
“The signal with maximum at 3405 is assigned to the stretching vibrations of OH groups in water molecules, while the bands cm-1 intensity at 3405 cm-1 is assigned to the stretching vibrations of OH groups in water molecules, while at wavenum”
Sodium Copper Chlorophyllin Immobilization onto Hippospongia communis Marine Demosponge Skeleton and Its Antibacterial Activity DOI: 10.3390/ijms17101564
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