What absorbs at 1671 cm⁻¹ in an FTIR spectrum?
A band near 1671 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 |
|---|---|---|---|
| Amide | 7 | 5 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| Carbonyl (C=O) | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 1 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Protein beta turn | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Protein beta sheet | 1 | 1 | 1.0 |
| Protein alpha helix | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Carbohydrate confidence 1.0
“SEM images are widely The peaks at 1671 and correspond to used to examine the surface morphology of polysaccharides the amide bonds and NH group, respectively.”
Almahamid 等 - 2022 - Application of Factorial Design and Response Surfa DOI: 10.1155/2022/1967606 -
Amide confidence 1.0
“The two major peaks at 1671 and 1564 were C‚O assigned to the stretching (amide I) and NH bending”
Mechanochemical synthesis of chitosan submicron particles from the gladius of Todarodes pacificus DOI: 10.1016/j.jare.2016.08.006 -
Acetate confidence 1.0
“ν(C=C) ν(C=O) 1653 0.3 0.1 + quinone C=O stretching in ν(C=C) ν(C=O) 1671 1.6 0.1 + quinone C=O stretching mode C=O COOH”
Water-Activated Semiquinone Formation and Carboxylic Acid Dissociation in Melanin Revealed by Infrared Spectroscopy DOI: 10.3390/polym13244403 -
Protein alpha helix confidence 1.0
“and amide III are shown in The amide I band (1230-1330cm-1) α-helix β-sheet are both caused by the skeleton band The characteristic peaks of and structures are 1652cm-1 1671cm-1, and respectively (Rosana et al., 2012).”
Du 等 - 2022 - Green and Highly Efficient Wool Keratin Extraction DOI: 10.3389/fmats.2021.789081 -
Hydroxyl (O-H) confidence 1.0
“The peak at 1671 was assigned to the first suffer The C vibrationsofunsaturatedaldehydestructures,andthesharppeak alcohol radical formed in the reaction can 8 cm-1”
Fu 等 - 2015 - Photosensitized Production of Atmospherically Reac DOI: 10.1021/jacs.5b04051 -
Amide confidence 1.0
“For MP, the following vibration peaks are recognized, such as stretching vibration of -NH at 2 cm-1, cm-1, cm-1, 3+ 3393 stretching vibration of -NH at 3155 stretching vibration of C-N at 1671 and”
He 等 - 2019 - Novel Intumescent Flame Retardant Masterbatch Prep DOI: 10.3390/polym11010050 -
Acetate confidence 1.0
“(cm-1) Frequency Band Assignment Species C-H 929 out-of-plane deformation 1018 Ring deformation 1081 Furfural 1156 =C-O-C= ring vibration 1279 1570 C=C stretches 1696 C=O aldehyde stretch 1671 C-O 1163 acid stretch vibration 1369 CH symmetr”
Solubility Temperature Dependence of Bio-Based Levulinic Acid, Furfural, and Hydroxymethylfurfural in Water, Nonpolar, Polar Aprotic and Protic Solvents DOI: 10.3390/pr9060924 -
Protein beta turn confidence 1.0
“As displayed in we observed eight major absorptions for the pure PTyr-TPA: for the aromatic ring vibrations from Figure10A,weobservedeightmajorabsorptionsforthepurePTyr-TPA:forthearomaticringvibrations PTyr (1595 and 1612 cm-1), the α-helic”
Supramolecular Interactions Induce Unexpectedly Strong Emissions from Triphenylamine-Functionalized Polytyrosine Blended with Poly(4-vinylpyridine) DOI: 10.3390/polym9100503
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