C13 NUCLEAR MAGNETIC RESONANCE (NMR)

13C NMR C13 resonances occur from 0 to 200 ppm ().

These peaks are split by the attached hydrogens.

However, proton decoupled (broadband) spectra are not split by H.

13C NMR Distortionless enhancement by polarization transfer (DEPT) spectra permit identification of CH3, CH2, and CH carbon atoms.

DEPT 45 shows 1o, 2o,and 3o carbons.DEPT 90 shows only 3o carbons.DEPT 135 shows 1o and 3o carbons as positive peaks and 2o carbons as negative peaks.

13C NMR

H1

H environment, ppmH environment, ppm

defined0Acetylenic~2.5

Saturated carbonsAromatic~6.5-8

primary~0.9

secondary~1.3Ester3.5-4.5

tertiary~1.6

Acid10-12

Olefinic carbons4.5-6

4.5-6Aldehyde9-10

4.5-6

1.5-2

2.5-41-5

C13

C environment, ppmC environment, ppm

Saturated carbons0-55Acetylenic60-90

primary4-30

secondary12-50Benzenoid120-140

tertiary22-54

quaternary29-47Carbonyl150-220

amides & imides150-180

Olefinic carbons100-165esters & anhydrides155-185

100-110acids170-190

110-120ketones185-220

125-150aldehydes190-210

130-154

140-165Nitriles115-125

AlenesAzomethine145-165

70-95

200-215

Sheet3

13C Off-resonance decoupled spectrum

13C Off-resonance & Broadband decoupled spectraBroadbandOff-resonance

13C Broadband decoupled spectrum

13C NMR n-HexaneBroadband

13C NMR AcetoneBroadband

Broadband1H & 13C NMR: 1,1,2-trichloropropane

1H & 13C NMR: 2-methyl-2-buteneBroadband

1H & 13C NMR: 2-methyl-1-buteneBroadband

13C NMR 6-methyl-5-hepten-2-olBroadbandAll carbons as singlets

13C NMR 6-methyl-5-hepten-2-ol DEPT 90Only CH carbons

13C NMR 6-methyl-5-hepten-2-olDEPT 135Methyl and CH positiveMethylene negative

ENDC13 NMR

C environment , ppmC environment , ppm

Saturated carbons 0-55Acetylenic

-

C C

-

60-90

primary

R-

C

H

3

4-30

secondary

R

2

-

C

H

2

12-50Benzenoid 120-140

tertiary

R

3

-

C

H

22-54

quaternary

R

4

-

C

29-47Carbonyl

C

=O

150-220

amides & imides150-180

Olefinic carbons 100-165 esters & anhydrides155-185

R

2

C=

C

H

2

100-110 acids170-190

R-CH=

C

H

2

110-120 ketones185-220

R-CH=

C

H-R

125-150 aldehydes190-210

CH

2

=

C

H-R

130-154

CH

2

=

C

R

2

140-165Nitriles

R-

C

N

115-125

Alenes Azomethine

R

2

C

=N-R

145-165

C

=C=

C

70-95

C=

C

=C

200-215