What absorbs at 1707 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1707 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

Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.

Possible materials

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 1707 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

• Carboxyl (COOH) confidence 1.0

  “Based on Figure cm-1) the best conditions to synthesize TMP triesters, Di-TMP 6, the carboxylic acid of CPKFAs peaks (1707”

  Bahadi 等 - 2022 - Synthesis of ISO Grade 46 and 68 Biolubricant from DOI: 10.17576/jsm-2022-5108-13
• Carbonyl (C=O) confidence 1.0

  “PG shows two characteristic peaks at 1707 (first from the left) and cm-1 1668 (second from the left) corresponding to stretching vibration of carbonyl groups at C20 and C3, respectively (Figure 1).”

  Chen 等 - 2020 - Solubility Improvement of Progesterone from Solid DOI: 10.3390/polym12040854
• Carboxyl (COOH) confidence 1.0

  “region), carbonyl groups of 1707cm-1), carboxylic acids (peaks centered at and aromatic 72 J.A.”

  Fossil cutin of Johnstonia coriacea (Corystospermaceae, Upper Triassic, Cacheuta, Argentina) DOI: 10.1016/j.coal.2018.02.016
• Hydrogen bond confidence 1.0

  “According to this idea, the peak at 1747 appeared at the high temperC@O, C@O ature, came from two new kinds of which were probwas possible to a free stretching vibration mode C@O cm(cid:2)1 ably assigned to strong hydrogen bonding and free”

  Lai 和 Wu - 2008 - Investigation on the conformations of AOT in water DOI: 10.1016/j.molstruc.2008.01.017
• Ester confidence 1.0

  “cm-1 (1) EPMC due to the absorption at 1707 of the In this step, two amine compounds were used, namely cm-1 carbonyl ester strengthened by the band at 1186.86 phenethylamine and morpholine, to produce N-”

  Rasyid 等 - 2022 - Synthesis of N-phenethyl-p-methoxycinnamamide and DOI: 10.22146/ijc.76802
• Urethane confidence 1.0

  “FTIR spectroscopy analysis showed photodegradation of irradiated PUE with lower intensity of cm-1 1530cm-1 C]O C]C and peaks at 1707 and corresponding to breaking of urethane bond.”

  Wong 等 - 2019 - Photo-activated self-healing bio-based polyurethan DOI: 10.1016/j.indcrop.2019.111613
• Acetate confidence 1.0

  “Further, it was found that the C=O band at 1707 was almost disappeared with GO-PDA demonstrating a partial reduction of GO NPs [28].”

  Polydopamine Functionalized Graphene Oxide as Membrane Nanofiller: Spectral and Structural Studies DOI: 10.3390/membranes11020086
• Carbonyl (C=O) confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Ashri 和 Lazim - 2014 - A Study on the Effect of the Concentration of N,N- DOI: 10.1063/1.4895204