NMR Testing Laboratory

Industrial NMR Spectroscopy Applications

Table 2 13C NMR

Chemical Shift Table 2
13C NMR Chemical Shift Peak Assignment for Functional Groups of Interest in Petroleum Chemistry.
Peak Position* Assignment
11.0 – 12.5 CH3 gamma or further from aromatic ring. CH3 in ethyl substituted cyclohexane.
12.5 – 15.0 CH3 gamma or further from aromatic ring. CH3 a shielded ny two adjacent rings or groups.
15.0 – 18.0 CH3 beta in ethyl.
18.0 – 20.5 CH3 alpha shielded ny one adjacent ring or group. Some CH3 alpha hydroaromatic and naphthenic CH2.
20.5 – 22.5 CH3 not shielded by adjacent rings or groups. Some CH3 alpha hydroaromatic and naphthenic CH2.
22.5 – 24.0 CH2 gamma and further adjacent to terminal CH3. Ch2 beta in unsubstituted tetralin structures. Some CH3 alpha hydroaromatic and naphthenic CH2.
24.0 – 27.5 Some CH2 naphthenic. CH alpha not shielded. CH2 beta in propyl and indan groups. CH3 beta in isopropyl.
27.5 – 37.0 CH2 not adjacent to CH in alkyl groups. CH2 adjacent to alkyl CH in some CH2 alpha and CH2 adjacent to terminal CH3 in alkyl substituents with more than four carbons. CH2 in ring joining ethylene groups. Some CH2 naphthenic. Some ring joining methylene (32-43 ppm).
37.0 – 60.0 CH alkyl groups (except isoalkyl). Naphthenic CH. CH2 alkyl groups adjacent to CH. Some ring joining methylene (32-43 ppm).
108.0 – 118.0 Some olefinic (others spread through aromatic region).
118.0 – 129.5 Protonated aromatic. Some internal (quaternary) aromatic.
129.5 – 133.0 Most internal aromatic.
133.0 – 135.0 Methyl substituted aromatic.
135.0 – 138.0 Naphthenic substituted aromatic.
138.0 – 160.0 Alkyl (other than methyl) substituted aromatic. Heteroatom (N, O, S) aromatic.
165.0 – 175.0 Ester or Amide Carboxyl.
170.0 – 182.0 Acid Carboxyl.
182.0 – 192.0 Quinone Carboxyl.
195.0 – 205.0 Aldehyde Carbonyl.
202.0 – 220.0 Ketone Carbonyl.
* Referenced to TMS (tetramethylsilane) at 0 ppm (units = ppm)