What absorbs at 3672 cm⁻¹ in an FTIR spectrum?
A band near 3672 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 7 cited sources
Quick answer
A band near 3672 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
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 3672 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
-
confidence 1.0
“2003) 03 cm-1, shows a broad peak centered at 3672 assigned to the CaCa and Al-bearing tremolite/richterite (Hawthorne et al.”
Synthesis and characterization of amphiboles along the tremolite–glaucophane join DOI: 10.2138/am.2013.4281 -
Alkyl C-H confidence 1.0
“3533cm-1 tion peaks at 3672 and represent C-H stretching of UHMWPE polymer.”
Aarya 等 - 2021 - Gamma Rays Induced Modification in Ultrahigh Molec DOI: 10.1155/2021/7013154 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Hydrogenating activity of Pt/zeolite catalysts focusing acid support and metal dispersion influence DOI: 10.1016/j.apcata.2015.03.027 -
Acetate confidence 1.0
“The new characteristic peaks at 3732 cm-1, 3672 cm-1 and 3648 cm-1 cm-1 and C-O [35,36], and the characteristic peaks at 665 are caused by the bending of of bastnaesite treated with NHA are caused by the tensile vibration of N-H and C-O nap”
Selective Adsorption of 2-Hydroxy-3-Naphthalene Hydroxamic Acid on the Surface of Bastnaesite and Calcite DOI: 10.3390/min12111341 -
Hydroxyl (O-H) confidence 0.95
“Explicit assignment in text: 'free OH stretch at ... 3672'”
Moakes 等 - 2006 - Solvation dynamics of lithium salts in wet nitrobe DOI: 10.1016/j.jelechem.2006.03.028 -
confidence 0.8
“Listed under same assignment.”
Kumar 等 - 2015 - Fourier transform infrared spectroscopy (FTIR) ana DOI: 10.1007/s13197-015-1959-0 -
Hydroxyl (O-H) confidence 0.8
“narrow band at 3672 attributed to O-H in SAPO-18”
Valecillos 等 - 2020 - Quenching the Deactivation in the Methanol-to-Olef DOI: 10.1021/acs.iecr.0c01616
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