○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
18
6b
7
1a. (+)-(2R,4S)-cis-rose oxide
1b. (-)-(2S,4R)-cis-rose oxide
2a. (-)-(2R,4R)-trans-rose oxide
2b. (+)-(2S,4S)-trans-rose oxide
3. isomenthone
4. menthone
5a. (-)-(R)-linalool
5b. (+)-(S)-linalool
6a. (-)-(S)-
β
-citronellol
6b. (+)-(R)-
β
-citronellol
7. geraniol
8. citronellyl formate
Figure 21A
The Rt-
β
DEXsa column provides chiral resolution for cis and trans rose
oxides, linalool, and
β
-citronellol in Chinese Geranium oil.
Figure 21B
The Rt-
β
DEXsa column reveals authenticity of Rose oil Maroc.
1a
40
min. 30
50
60
40
min. 30
50
60
1b
2a
2b
3
4
5a 5b
6a
8
1. (-)-(2S,4R)-cis-rose oxide
2. (-)-(2R,4R)-trans-rose oxide
3a. (-)-(R)-linalool
3b. (+)-(S)-linalool
4. phenylethyl alcohol
5a. (-)-(S)-
β
-citronellol
5b. (+)-(R)-
β
-citronellol
6. geraniol
6
1
2
3a
4 5a
5b
3b
Geranium oils provided by Belmay.
30m, 0.25mm ID, 0.25µmRt-
β
DEXsa (cat.# 13109);
Oven temp.:
60°C to 110°C@ 1°C/min. (hold 30min.);
Carrier gas:
hydrogen; 40cm/sec. set @ 60°C;
Detector:
FID set @ 220°C
30m, 0.25mm ID, 0.25µmRt-
β
DEXsa (cat.# 13109);
Oven temp.:
60°C to 110°C@ 1°C/min. (hold 30min.);
Carrier gas:
hydrogen; 40cm/sec. set @ 60°C;
Detector:
FID set @ 220°C
GeraniumOil
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Chiral constituents in geranium oils
include cis and trans rose oxides,
linalool, and
β
-citronellol. The Rt-
β
DEXsacolumnprovideschiral reso-
lution for all of these compounds. In
authentic samples of geranium oil,
(-)-(4R)-configured diastereomers of
cis- and trans-rose oxides predomi-
nate over their (+)-enantiomers.
3
The
(-)-(S) form of
β
-citronellol is 74-80%
of the enantiomeric ratio.
4
Note that
cis- and trans-rose oxides and
β
-cit-
ronellol are racemic in this particu-
lar commercial geranium oil, as
shown in
Figure21A
. These racemic
compounds indicate that this oil is
not authentic.
RoseOil
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Aswith geranium oils, (-)-(2S,4R)-cis
and (-)-(2R,4R)-trans rose oxides and
(-)-(S)-
β
-citronellolarespecific indica-
tors of genuine rose oils.
5
Note the
enantiomeric purity of these com-
pounds inRoseOil Maroc, as shown
in
Figure 21B
.
Visit Restek on-line at
,
or call 800-356-1688,
ext. 4, for technical
assistance.
