What absorbs at 2867 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 2867 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 2867 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

• Alkyl C-H confidence 1.0

  “CH CH bending at 1354 are lower than those in Xoo strains asymmetric stretching band at 2867 and The ratio 3 3”

  Differentiation in MALDI-TOF MS and FTIR spectra between two pathovars of Xanthomonas oryzae DOI: 10.1016/j.saa.2014.06.056
• Alkyl C-H confidence 1.0

  “In 250◦C 20◦C/min and the scanning rates were under nitrogen to cm-1is case of pure BC, a band at 2867 attributed to the aliphatic the atmosphere.”

  Laccase-assisted grafting of poly(3-hydroxybutyrate) onto the bacterial cellulose as backbone polymer: Development and characterisation DOI: 10.1016/j.carbpol.2014.07.003
• Chitosan confidence 1.0

  “Similar peaks were also found in chitosan (3361cm-1, 2867cm-1),”

  Meng 等 - 2020 - Effects of peanut shell and skin extracts on the a DOI: 10.1016/j.ijbiomac.2020.02.235
• Alkyl C-H confidence 1.0

  “The chemical modification process 2867.18cm-1 𝑑-spacing are due to the C-H stretching in spectrum 3(b).”

  Liau 等 - 2014 - Preparation and Characterization of Polyhydroxybut DOI: 10.1155/2014/572726
• Alkyl C-H confidence 1.0

  “3459 3454 3454 2956,2927, 3088,2993,2960, 2956,2927, 2956,2927, 2956,2927,2856 2961,2902 2961,2902 - 3088 - - C-H(CH2)stretchingalkane 2867 2933,2833 2875-2859 2875-2859 2956, 2956,”

  Mikolaszek 等 - 2022 - Microscopic and Spectroscopic Imaging and Thermal DOI: 10.3390/polym14142888
• Alkyl C-H confidence 1.0

  “Strong peaks with two maxima at 2924 cm-1 and 2867 cm-1 are due to aliphatic C-H stretch of alkyl groups.”

  Odlyha 等 - 2022 - Violin Varnishes Microstructure and Nanomechanica DOI: 10.3390/molecules27196378
• Alkyl C-H confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Wairkar 和 Gaud - 2016 - Co-Amorphous Combination of Nateglinide-Metformin DOI: 10.1208/s12249-015-0371-4
• Alkyl C-H confidence 1.0

  “A small cm-1 peak at 2867 appeared due to aliphatic stretching of (C-H).”

  Yadav 和 Urade - 2019 - Formulation and Evaluation of Chitosan Based Trans DOI: 10.5530/ijper.53.1.12