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Table 2
13C
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 by two adjacent rings
or groups
15.0-18.0
CH3 beta
in ethyl
18.0-20.5
CH3 alpha
shielded by 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).