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¹³C NMR chemical shift table and how to use it

A ¹³C NMR spectrum shows one peak for each different carbon environment. The number of peaks tells you about symmetry, and where they are tells you what each carbon is attached to.

Spectroscopy · Updated 5 November 2026

Chemical shift table

Type of carbonδ / ppm
C–C (alkyl CH₃, CH₂, CH)5–40
C–Cl, C–Br10–70
C next to C=O (R–C–C=O)20–50
C–N (amines)25–60
C–O (alcohols, ethers, esters)50–90
C=C (alkenes)90–150
C≡N (nitriles)110–125
Aromatic carbons110–160
C=O in acids, esters and amides160–185
C=O in aldehydes and ketones190–220

Ranges vary a little between data booklets. Use the one your exam board gives you.

How to read a spectrum

  1. Count the peaks. Each one is a different carbon environment. Fewer peaks than carbons means the molecule has symmetry.
  2. Look above 160 ppm for C=O. Above 190 is an aldehyde or ketone; 160–185 is an acid, ester or amide.
  3. Look at 110–160 for aromatic or alkene carbons, and 50–90 for carbons bonded to oxygen.
  4. Match the rest to alkyl carbons below 50 ppm.

In a normal (proton-decoupled) ¹³C spectrum every peak is a single line, and peak heights are not proportional to the number of carbons. Don't try to integrate them as you would in ¹H NMR.

Counting carbon environments

O
propanone: 2 peaks (both CH₃ are equivalent), C=O near 206 ppm
OH
propan-1-ol: 3 peaks, C–O near 64 ppm
OH
propan-2-ol: 2 peaks, because the molecule is symmetrical
OO
ethyl ethanoate: 4 peaks, ester C=O near 171 ppm
benzene: 1 peak (128 ppm), all six carbons are equivalent
methylbenzene: 5 peaks (CH₃, and four ring environments)

Worked example

C₃H₆O, three peaks at 7, 37 and 203 ppm. The peak above 190 ppm is an aldehyde or ketone C=O. Propanone would give only two peaks (it's symmetrical), so this must be propanal, CH₃CH₂CHO: three different carbons.

Combine ¹³C with ¹H NMR to get the full structure: see ¹H NMR splitting and the n+1 rule.

Quick answers

What does the number of peaks in a 13C NMR spectrum tell you?

Each peak is one carbon environment. The number of peaks is the number of different kinds of carbon, which is less than the total number of carbons if the molecule has symmetry.

Where does C=O appear in 13C NMR?

Aldehyde and ketone C=O carbons appear at about 190–220 ppm. Carboxylic acid, ester and amide C=O carbons appear at about 160–185 ppm.

Why are 13C NMR peaks not split?

Spectra are normally run proton-decoupled, so the coupling to hydrogens is removed and each carbon environment gives a single line.

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