Synthesis and Chromatographic Evaluation of the new phase heptakis (3-O-pentafluoropropionyl-2,6-di-O-pentyl)-β-cyclodextrin

Abstract

Neste trabalho uma nova fase estacionária quiral, heptaquis (3-O-pentafluoropropionil-2,6-di-O-pentil)-b-ciclodextrina, foi sintetizada e avaliada frente uma grande variedade de compostos voláteis quirais. O novo derivado de ciclodextrina foi usado para a separação de componentes de óleos essenciais, como hidrocarbonetos, cetonas, aldeídos, álcoois de cadeia longa, compostos halogenados e compostos contendo nitrogênio e enxofre.In this work, a new chiral stationary phase heptakis (3-O-pentafluoropropionyl-2,6-di-Opentyl)-b-cyclodextrin was synthesized and evaluated with a wide variety of volatile chiral compounds. As a result, the new cyclodextrin derivative can be applied to the separation of chiral components of essential oils, as hydrocarbons, ketones, aldehydes, alcohols and of various classes of synthetic chiral compounds, as long chain alcohols, halocarbons, nitrogen and sulfur containing compounds. Keywords: enantioselective gas chromatography, heptakis (3-O-pentafluoropropionyl-2,6-di-O-pentyl)-b-cyclodextrin, pentafluoropropionyl group IntroductionCyclodextrins (CDs) derivatives, especially those of a-, b-and g-cyclodextrins, are used widely as chiral stationary phases (CSPs) in gas chromatography (GC) as an efficient method for enantioseparation of a wide variety of volatile compounds of different functionality. [1][2][3][4][5][6][7][8][9][10][11] Various chiral mono and sesquiterpenes common to essential oils and other economically important products could be resolved on columns coated with per-O-alkylated/acylated cyclodextrins. [11][12][13][14][15][16] The number of cyclodextrin derivatives that is prepared and evaluated for enantioselective gas chromatography is still declining in recent years. The most important chiral stationary phases know to data, as octakis (3-O-butyryl-2,6-di-O-pentyl)-g-cyclodextrin (Lipodex E) 17 , heptakis (3-O-pentyl-2,6-di-O-methyl)-bcyclodextrin 18 and octakis (3-O-methyl-2,6-di-O-pentyl)-gcyclodextrin 12 , were obtained in the late 80's and 90's. In this work we describe the preparation and the enantioseparation ability of heptakis (3-O-pentafluoropropionyl-2,6-di-O-pentyl)-b-cyclodextrin derivative with pentyl groups at the 2 and 6 positions and the pentafluoropropionyl group in the 3 position of their glucose unit. The pentafluoropropionyl group is used as hydroxyl group protection in oligomannoside synthesis, 19 but not used yet as derivatizing agent in CDs. The enantioselectivity of the new phase was evaluated with a number of natural chiral components of essential oils as hydrocarbons, alcohols, ketones and lactones, and determination of enantiomeric composition in asymmetric synthesis. The enantiomers of (+/-)-a-pinene, (+/-)-limonene, alcohols as (+/-)-menthol, (+/-)-neo-menthol, (+/-) borneol, (and its acetyl and/or O-trifluoroacetyl derivatives), ketones as (+/-)-carvone, (+/-)-camphor and (+/-)-a-ionone could be resolved. In addition, chiral secondary and tertiary long chain alcohols, halocarbons, nitrogen and sulfur containing compounds may also be resolved....