Get Infrared Tables (short Summary Of Common Absorption Frequencies ...

The carbonyl stretching absorption is one of the strongest IR absorptions, and is very useful in structure determination as one can determine both the number of carbonyl groups (assuming peaks do not overlap) but also an estimation of which types.

There are five prominent water absorption bands in the near infrared which occur at 0.76, 0.97, 1.19, 1.45, and 1.94μ. A weaker band occurs at 0.845μ.

The absorption bands in IR spectra have different intensities that can usually be referred to as strong (s), medium (m), weak (w), broad and sharp. The intensity of an absorption band depends on the polarity of the bond, and a bond with higher polarity will show a more intense absorption band.

Infrared (IR) spectroscopy is an absorption method widely used in both qualitative and quantitative analyses. The infrared region of the spectrum includes electromagnetic radiation that can alter the vibrational and rotational states of covalent bonds in organic molecules.

Typical IR Absorption Frequencies For Common Functional Groups BondFunctional GroupFrequency in cm−1 (Intensity*)Free3650–3600 (m)Hydrogen‐bonded3500–3200 (m)Carboxylic Acids3300–2400 (m)N–HPrimary and Secondary Amine and Amide3550–3060 (m‐s); 1640–1550 (m‐s)24 more rows

IR Spectrum Table by Frequency Range Absorption (cm-1)AppearanceCompound Class3333-3267strong, sharpalkyne3100-3000mediumalkene3000-2840mediumalkane2830-2695mediumaldehyde127 more rows