What absorbs at 1736 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1736 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 1736 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

  “NMR studies showed the carboxyl bands, but also featured additional peaks at 1736 and 1134 presence of butyl groups.”

  Broderick 等 - 2006 - The characterisation of a novel, covalently modifi DOI: 10.1016/j.jcis.2005.12.026
• Borate confidence 1.0

  “Additionally, changes B-O in the peak profile of the stretching band were observed upon binding, confirming formation of a (cid:24)1736 cm-1 through the IR marker mode at to 1742 depending on the identity of the bound sugar.”

  Brewer 等 - 2004 - Infrared detection of a phenylboronic acid termina DOI: 10.1021/la035037m
• Acetate confidence 1.0

  “The bands at 2243 and 1736 cm-1 are due to CN stretching and C=O stretching vibrations, Fabrication of Conductive Composite Films”

  Cetiner 等 - 2011 - Characterization of Conductive Poly(Acrylonitrile- DOI: 10.1007/s12221-011-0151-z
• Acetate confidence 1.0

  “The FTIR cm-1 analysis of synthesis of ZnO NPs using seaweeds showed the bands at 1736 representing C=O cm-1, which were sharper and broader for ZnO carboxylic acid and the strong C-H group bonds at 1023”

  An Investigation of the Cytotoxicity and Caspase-Mediated Apoptotic Effect of Green Synthesized Zinc Oxide Nanoparticles Using Eclipta prostrata on Human Liver Carcinoma Cells DOI: 10.3390/nano5031317
• Ester confidence 1.0

  “Hence the cm(cid:3)1 that the peak at (cid:2)1715 is the ester carbonyl formed by the can be attributed to the ester carbonyl peak at 1736 reaction of the anomeric hydroxyl of glucose with the formed by the reaction of the secondary hydroxy”

  Galgali 等 - 2007 - Sugar-linked biodegradable polymers Regio-specifi DOI: 10.1016/j.carbpol.2006.06.035
• Carbon dioxide confidence 1.0

  “The tion of SWCNTs to the Type(cid:2)4 blend, a new small peak reduction of O=C=O peak area (A 4) on consecutive cm-1 cm-1) at 1736 and a broad peak (1210-990 cen(cid:2) addition of SWCNT and compatibilizer signifies cm-1 tered at 1088 were”

  Khan 等 - 2015 - Morphological characteristics of solution spun nan DOI: 10.1134/S0965545X15060115
• Carboxyl (COOH) confidence 1.0

  “Degree of methylation (DM) 223 cm-1 From [21], it is inferred that the ratio of the area of the band at 1736 224 (corresponding to the number of esterified carboxylic groups) over the sum of the areas 225 cm-1and cm-1 of the bands at 1735 1”

  Lefsih 等 - 2016 - Extraction, characterization and gelling behavior DOI: 10.1016/j.ijbiomac.2015.10.046
• Ester confidence 1.0

  “gas41, cm-1, cm-1, cm-1 cm-1 are attributed to hydrogen chloride the peaks near 1736 1264 1106 and 1024 are DOTP42, cm-1 attributed to the ester group ν from the plasticizer and the 671 peak is attributed to the (COOR)”

  Synthesis, characterization and thermal behavior of plasticized poly (vinyl chloride) doped with folic acid-modified titanium dioxide DOI: 10.1038/s41598-022-07177-5