Isocyanate — FTIR absorption peaks and assignments
These are the characteristic FTIR wavenumbers where Isocyanate tends to absorb, compiled from published literature and ranked by supporting evidence. Each assignment is traceable to a source (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
Isocyanate is usually assigned by looking for a recurring cluster of characteristic peaks rather than one exact textbook number. The table below shows where the literature most often places this group in FTIR, ranked by accumulated evidence.
Characteristic FTIR peaks for Isocyanate
| Wavenumber (cm⁻¹) | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| 2270 | 15 | 13 | 1.0 |
| 2250 | 7 | 5 | 1.0 |
| 2266 | 5 | 5 | 1.0 |
| 2252 | 2 | 2 | 1.0 |
| 2260 | 2 | 1 | 1.0 |
| 2360 | 1 | 1 | 1.0 |
| 1647 | 1 | 1 | 1.0 |
| 1689 | 1 | 1 | 1.0 |
| 2273 | 1 | 1 | 1.0 |
| 524 | 1 | 1 | 1.0 |
| 2263 | 1 | 1 | 1.0 |
| 2271 | 1 | 1 | 1.0 |
| 1445 | 1 | 1 | 1.0 |
| 2253 | 1 | 1 | 1.0 |
| 2276 | 1 | 1 | 1.0 |
| 2850 | 1 | 1 | 1.0 |
| 2350 | 1 | 1 | 1.0 |
| 2097 | 1 | 1 | 1.0 |
| 2142 | 1 | 1 | 1.0 |
| 2264 | 1 | 1 | 1.0 |
| 2280 | 1 | 1 | 1.0 |
| 2262 | 1 | 1 | 1.0 |
| 2240 | 1 | 1 | 1.0 |
| 2281 | 1 | 1 | 1.0 |
| 2275 | 1 | 1 | 1.0 |
| 2244 | 1 | 1 | 1.0 |
| 2258 | 1 | 1 | 1.0 |
| 1639 | 1 | 1 | 1.0 |
| 2241 | 1 | 1 | 0.95 |
| 1526 | 1 | 1 | 0.7 |
Showing the 30 best-supported peaks of 32 total for Isocyanate.
Spectrum logic
A functional-group assignment becomes more confident when several expected bands appear together. Use this page to find the strongest-supported peaks, then confirm that the same sample exhibits a coherent pattern rather than a single isolated hit.
Real-world usage
These pages are useful for unknown material analysis, peak explanation in reports, polymer troubleshooting, and verifying whether a candidate material family is chemically plausible.
Common mistakes
- Using one functional-group page as a complete material verdict without checking the rest of the spectrum.
- Assuming the strongest band is always the most diagnostic one.
- Forgetting that processing, additives, aging, and mixtures can shift or broaden expected peaks.
Verification advice
Use DSC, GC-MS, or TGA when several material families share similar bands or when mixture effects make the FTIR assignment uncertain.
Literature behind these assignments
-
2270 cm⁻¹ confidence 1.0
“Samples were canbeobserved[17].Thereactionbetweenurethaneprepolymerand dehydratedingradedalcohols(10,30,50,70,80,85,90,95,and100%) polyvinyl alcohol indicates the absence of isocyanate peaks (NCO) at 2270cm-1.”
Preparation and characterization of polyvinyl alcohol hydrogels crosslinked by biodegradable polyurethane for tissue engineering of cartilage DOI: 10.1016/j.msec.2010.02.017 -
2270 cm⁻¹ confidence 1.0
“LLM confirmed rule peak-group candidate”
Curing reaction kinetics of HTPE polymer studied by simultaneous rheometry and FTIR measurements DOI: 10.1007/s10973-016-5485-8 -
1639 cm⁻¹ confidence 1.0
“Small band at 1639 belongs to carbonyl (-C=O) with C=O-NH arrangements of traces of urea which may be present due to the reaction of excess isocyanate with moisture in air.”
Preparation and characterization of aliphatic polyurethane and modified hydroxyapatite composites for bone tissue engineering DOI: 10.1007/s00289-019-03067-5 -
2258 cm⁻¹ confidence 1.0
“LLM confirmed rule peak-group candidate”
In situ FTIRATR studies on the structure development of polyurethaneurea systems DOI: 10.1002/app.34199 -
2266 cm⁻¹ confidence 1.0
“LLM confirmed rule peak-group candidate”
Reaction kinetics of dicyclohexylmethane-4,4[prime]-diisocyanate with 1- and 2-butanol: A model study for polyurethane formation DOI: 10.1002/app.28320 -
2250 cm⁻¹ confidence 1.0
“LLM confirmed rule peak-group candidate”
Degradation of polyester polyurethane by an indigenously developed consortium of Pseudomonas and Bacillus species isolated from soil DOI: 10.1016/j.polymdegradstab.2016.11.003 -
2244 cm⁻¹ confidence 1.0
“the disappearance of isocyanate peak at 2244 using FTIR-ATR.”
Shoaib 和 Bahadur - 2016 - Synthesis of thermally and mechanically improved p DOI: 10.1515/epoly-2016-0134 -
2270 cm⁻¹ confidence 1.0
“cm-1 cm-1 N=C=O peak at 2270 was ascribed to bonds.”
Novel Polyvinyl Alcohol (PVA)/Cellulose Nanocrystal (CNC) Supramolecular Composite Hydrogels: Preparation and Application as Soil Conditioners DOI: 10.3390/nano9101397
See Isocyanate in your own spectrum
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.