What absorbs at 2250 cm⁻¹ in an FTIR spectrum?
A band near 2250 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
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Isocyanate | 6 | 5 | 0.95 |
| Nitrile | 3 | 3 | 0.9 |
| Amide | 2 | 1 | 0.95 |
| C#c | 1 | 1 | 0.9 |
| Carbon dioxide | 1 | 1 | 0.6 |
| Silicon hydride | 1 | 0 | 0.9 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Isocyanate confidence 0.95
“Explicit assignment in text: '2250 cm-1 for the N=C=O stretching vibration'”
Gregori Valdes 等 - 2018 - Synthesis and Characterization of Isosorbide-Based DOI: 10.3390/polym10101170 -
Amide confidence 0.95
“Explicit assignment: 'characteristic peak at ... 2250 ... assigned to HNCO'.”
Zhai 等 - 2021 - Thermal decomposition of ammonium perchlorate-base DOI: 10.1039/d0ra10559g -
Isocyanate confidence 0.9
“Text: 'new peak at 2250 ... corresponds to free isocyanates'”
Shah 等 - 2016 - Degradation of polyester polyurethane by an indige DOI: 10.1016/j.polymdegradstab.2016.11.003 -
Isocyanate confidence 0.9
“Peak at 2250 cm-1 indicates presence of remaining isocyanate.”
Galhenage 等 - 2017 - Poly(ethylene) glycol-modified, amphiphilic, silox DOI: 10.1007/s11998-016-9862-9 -
Isocyanate confidence 0.9
“Isocyanate groups from HMDI have important group at about 2250 cm-1.”
Ilmiati 等 - 2017 - Added value of lignin as lignin-based hybrid polyu DOI: 10.1088/1757-899X/223/1/012033 -
C#c confidence 0.9
“Explicit assignment.”
Maciel Lavra 等 - 2017 - Solubility and dissolution performances of spray-d DOI: 10.1080/03639045.2016.1205598 -
Isocyanate confidence 0.9
“Characteristic ν vibration at 2250 cm-1 for isocyanate.”
Risangud 等 - 2016 - Polyurea Microcapsules from Isocyanatoethyl Methac DOI: 10.1002/pola.28149 -
Nitrile confidence 0.9
“Explicit assignment in table.”
Ruggeri 和 Takahama - 2016 - Technical Note Development of chemoinformatic too DOI: 10.5194/acp-16-4401-2016
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