What absorbs at 1368 cm⁻¹ in an FTIR spectrum?
A band near 1368 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 1368 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 | 10 | 9 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Methyl | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Ester | 2 | 1 | 1.0 |
| Carbonyl (C=O) | 2 | 1 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Acetyl | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Boron nitrogen | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 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 |
|---|---|---|---|
| cotton | 1368, 1030, 1638 | Alkyl C-H, C-O single bond, Methoxy (OCH3) | 1 |
| gold nanoparticles | 1368, 1638, 3252 | Alkyl C-H, Hydroxyl (O-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 1368 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
“A cm-1 1368 cm-1 1024 C-H alkanes C-N stretch B”
A rapid method for fungal assisted algal flocculation: Critical parameters & mechanism insights DOI: 10.1016/j.algal.2016.10.022 -
confidence 1.0
“Gsi fun group analysis rubber-antioxidant compound IPPD / TMQ with FTIR spectrophotometer shows some λ) typical infrared absorption peak at the wave number (1 / 833-895 cm-1 for cluster / CH bonds, 1,313 cm-1 for group / single bond Si-O, 1”
Budiarto - 2017 - The Effect of Antioxidant Concentration of N-isopr DOI: 10.1063/1.4978141 -
Boron nitrogen confidence 1.0
“3(c)), a sharp peak at approximately 1368 was ascribed to the counter-phase B-N vibrational mode (E 2g)”
Kim 等 - 2015 - One-Pot Synthesis of h-BN Fullerenes Usinsg a Grap DOI: 10.1007/s12540-015-5043-0 -
Carbohydrate confidence 1.0
“1506cm-1 reactions21, and carbohydrate band at reference band at which led to the formation of surface photooxidation 1368cm-1 measured18,19.”
Study of the long-term degradation behavior of bamboo scrimber under natural weathering DOI: 10.1038/s41529-022-00273-x -
Alkyl C-H confidence 1.0
“1, the IR bands at 1740-1745 (carbonyl C=O stretching of ester), cm-1 1368 [C-H in -O(C=O)-CH 3] and 1234 (C-O stretching of acetyl group) provide evidence of acetylation.”
Adebajo 等 - 2006 - Raman spectroscopic investigation of acetylation o DOI: 10.1016/j.saa.2005.07.045 -
C-O single bond confidence 1.0
“cm-1 and (b) Mg(NO3)2, pure agarose and agarose-Mg(NO3)2 polymer electrolyte film 2 Other peaks belonging to agarose are the CH bond bending of an alkene group, 3 Other peaks belonging to agarose are the CH3 bond bending of an alkene group,”
Role of Mg(NO3)2 as Defective Agent in Ameliorating the Electrical Conductivity, Structural and Electrochemical Properties of Agarose–Based Polymer Electrolytes DOI: 10.3390/polym13193357 -
Alkyl C-H confidence 1.0
“Moreover, an absorption occurred occurred at ~1368 cm-1, due to the overlapping absorption of CH2 groups of lipids and of cm-1,”
Pathological ATX3 Expression Induces Cell Perturbations in E. coli as Revealed by Biochemical and Biophysical Investigations DOI: 10.3390/ijms22020943 -
Amide confidence 1.0
“The band at 1368 that corresponds to the C-N stretching vibration of aliphatic amines or alcohols/phenols may be responsible for the reduction and capping of AuNPs.”
Etlingera elatior-Mediated Synthesis of Gold Nanoparticles and Their Application as Electrochemical Current Enhancer DOI: 10.3390/molecules24173141
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