What absorbs at 2989 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 2989 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.

可能性のある官能基アサイン

ランキングは蓄積された文献証拠を反映しており、単一の権威あるルールではありません。常にサンプルのコンテキストと照合して確認してください。

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 2989 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.

これらのアサインの根拠となる文献

• Alkyl C-H 信頼度 1.0

  “peak at 2714 New peaks attributable to a dimethylacetal, C-H) HC(OCH 3) 2, appeared at 2832 (acetal carbon and 2989 cm-1 for the methyl groups.”

  Razgon 等 - 2008 - Ozonolysis-based route to the in situ formation of DOI: 10.1021/la703120c
• Alkyl C-H 信頼度 1.0

  “cm-1 In case of AMPS, peak at 2989 is attributed to C-H stretching of-CH2 group.”

  Development, characterization and In-vitro evaluation of guar gum based new polymeric matrices for controlled delivery using metformin HCl as model drug DOI: 10.1371/journal.pone.0271623
• Hydroxyl (O-H) 信頼度 1.0

  “The broad negative associated regions between 3259 Regression coefficients of xylose and glucose prediction cm-1 (r and 2989 correspond to the O-H stretching vibraThe high correlation = 0.82) of the measured glucose tion of various compound”

  Rapid estimation of sugar release from winter wheat straw during bioethanol production using FTIR-photoacoustic spectroscopy DOI: 10.1186/s13068-015-0267-2
• Alkyl C-H 信頼度 1.0

  “LLM confirmed rule peak-group candidate”

  Silva 等 - 2020 - Theoretical and Experimental Investigations on Inc DOI: 10.21577/0103-5053.20190273
• Imide 信頼度 1.0

  “The bismaleThe absorptions around 2989 and 2912 due to the m-cresol imide (1 g, 0.002321 mol) was dissolved in (3.5 mL) C-H stretching vibration of CH group as shown in Fig.”

  Sivasankari 等 - 2013 - Synthesis and Characterization of Thiophene Contai DOI: 10.14233/ajchem.2013.13514
• Alkyl C-H 信頼度 0.9

  “Explicit assignment from text.”

  Partial Biodegradable Blend with High Stability against Biodegradation for Fused Deposition Modeling DOI: 10.3390/polym14081541
• Hydroxyl (O-H) 信頼度 0.9

  “C-H vibration of OH group”

  Poly lactic acid production using the ring opening polymerization (ROP) method using Lewis acid surfactant combined iron (Fe) catalyst (Fe(DS)3) DOI: 10.1016/j.heliyon.2023.e17985