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Derivatization-Free Enantiomer Resolution of Chiral Alcohols and Ketones by High-Resolution Complexation Gas Chromatography.

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Derivatization-Free Enantiomer Resolution of
Chiral Alcohols and Ketones by High-Resolution
Complexation Gas Chromatography**
By Volker Schurig* and Roland Weber
Complexation gas chromatography offers a method of
precisely determining the enantiomeric purity of volatile
chiral natural products as well as of products of enantioselective reactions without derivatization"6'.
Previously used separation systems for underivatized alcohols and ketones['"' have the disadvantage of extremely
long retention times (several hours) and markedly asymmetric peaks arising either from insufficient pretreatment
of the capillary inner wall (coating efficiency <20%, high
surface activity) and/or from unfavorable properties of the
stationary phase (poor chiral recognition, insufficient temperature stability).
Here, we report a highly promising further development
of complexation gas chromatography using high resolution
glass and quartz capillary techniques. By deactivating the
glass or quartz surface (thermal cross-linking of Carbowax
20 MI3"]or OV 101[3b1)
and using methylsilicone OV 101 as
solvent for the optically active metal chelates, it has proved
possible to make capillary columns having a coating efficiency of > 80u/o. Using these columns, we were able to resolve quantitatively alcohols and ketones such as e. g.,
menthol, menthone, and isomethane into their enantiomers without derivatization within 20 minutes (Fig. 2).
In this way, particularly using the combination complexation gas chromatography/"selected-ion" mass spectrometry'"', the rapid, straightforward, and precise determination
of the enantiomeric composition of natural products from
complex mixtures can be performed directly[41. The enantiomer resolution of volatile chiral alcohols and ketones
by complexation gas chromatography is superior to the recently described resolution as urethane-, acyl-, or oximederivativesL5],since the disadvantages of derivatization
(sample preparation, incomplete reaction, occurrence of
by-products, and products of isomerization and racemization) can be avoided.
Received: May 18, 1983 [Z388 IE]
German version: Angew. Chem. 95 (1983) 797
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983, 1130-1137
[I] g) Cf. also V. Schurig, W. Burkle, J. Am. Chem. SOC.104 (1982) 7573, and
literature ciled therein.
(31 a) I>. A. Cronin, J . Chromutogr. 97 (1Y74) 263; b j G. Schomburg, J. Husmann, F. Weeke, Chromarographia 10 (1977) 580.
[4] V. Schurig, R. Weber, D. Klimetzek, U. Kohnle, K. Mori, Nnfurwi.nenschuften 6Y (1982) 602; V. Schurig, R. Weber, G. J. Nicholson, A. C.
Oehlschlager, H. Pierce Jr.. A. M. Pierce, J. H. Borden, L. C. Ryker, ibid.
70 (1983) 92: R. Weber, V. Schurig, F. Jiittner, unpublished results.
[S] W. A. Konig, W. Francke, I. Henecke, J . Chromutogr. 239 (1982) 227; W.
A. Konig, 1. Benecke, K. Ernst. ibid. 253 (1982) 267.
Quantitative Separation of Deuterated
Tetrahydrofurans C4&B)H4-,,n(a)D)n(a)0by
Complexation Gas Chromatography on a
Cobalt@) Complex**
By Yolker Schurig* and Dorothee Wistuba
I
15
5
t[minl
Fig. 2. Enantiomer resolution of menthone 5 , menthol 3, and isomenthone 6
on nickel(i1) bis[3-heptafluorobutyryl-(1Rj-campborate]
(0.08 M in the methyl
silicone fluid OV 101) at 133°C; carrier gas: 1.0 bar N2; Duran glass capillary (37 m x 0.75 mm).
Complexation gas chromatography"] uses the rapid and
reversible coordinative interaction between a mobile substrate and a stationary metal complex to solve particularly
difficult analytical separation problems. Whereas, previously, the enantiomer resolution of chiral donor molecules with heteroatoms having donor capabilities (O,S,N)
was of prime interest[lbl,we are now investigating the efficiency of the method for the quantitative separation of
protio/deuterio isomers of Lewis bases with mass difference 1.
[*I
Prof. Dr. V. Schurig, Dr. R. Weber
lnstitut fur Organische Chemie der Universitat
Auf der Morgenstelle 18, 11-7400 Tubingen 1 (Germany)
I**]
This work was supported by the Deutsche Forschungsgemeinschaft and
by the Fonds der Chemischen Industrie. Haarmann & Reimer and Dragoco, Holzminden, are thanked for samples of terpenes.
772
0 Verlug Chemie GmhH. 6940 Weinheim, 7983
[*I
[**I
Prof. Dr. V. Schurig, D. Wistuba
lnstitut fur Organische Chemie der Universitat
Auf der Morgenstelle 18, D-7400 Tubingen 1 (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industtie.
05711-0833/83/1010-0772 $ 02.50/0
Angew,. Chrm. I n t . Ed. Engl. 22 (1983) No. 10
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chiral, enantiomers, resolution, complexation, free, high, ketone, chromatography, gas, alcohol, derivatization
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