DE4324636A1 - Immobilised CHIRASIL-DEX for separation or detection processes - having cyclodextrin bonded to polymer chain and immobilised on smooth or porous carrier - Google Patents

Abstract

A cyclodextrin-contg. polymer (e.g. polysiloxane, block copolymer or smectic phase), has a chiral cyclodextrin derivative bonded to a polymer chain. It is immobilised on a smooth or porous surface of a carrier material (immobilised CHIRASIL-DEX). Also claims chromatographic separation or selective detection processes using the claimed material. ADVANTAGE - Greater stability without loss of selectivity.

Description

The invention relates to the immobilization of the chiral, cyclodextrin-containing stationary phase CHIRASIL-DEX on the surface of smooth or porous substrates and the use of the Trä modified with immobilized CHIRASIL-DEX phases Germ materials in packed columns for the selective separation of analytes by chro matographic and electrokinetic processes.

In inclusion chromatography, chiral cyclodextrin compounds are either as additives to non-volatile separating liquids (e.g. squalane or polysiloxanes in the Gas chromatography, GC), as solutions in the mobile phase (high pressure liquid chromatography, HPLC, in reverse phase mode), or in chemically fixed form in immobilized stationary phases (GC, SFC, CE, HPLC). To this Pha sen succeeds due to the fast and reversible inclusion interaction between Selector and selectand the chromatographic separation of structural isomers, geo metric isomers, isotopomers and in the case of chiral systems also the separation of enantiomers (cf. (1-5)).

• 1) Schurig, V., Schmalzing, D., Mühleck, U., Jung, M., Schleimer, M., Mussche, P., Duvekot, C., Buyten, J.C., J. High Res. Chromatogr., 13 (1990), 713
• 2) Schmalzing, D., Jung, M., Mayer, S., Rickert, J., J. High Res. Chromatogr., 15 (1992) 723
• 3) Schurig, V., Schmalzing, D., Schleimer, M., Angew. Chem., 1991, 103: 994
• 4) Jung, M., Schurig, V., J. Microcol. Sep., 5 (1993), 11
• 5) Mayer, S., Schurig, V., J. Liquid Chromatogr., 16 (1993), 915.

Due to the very high solvency of liquid or supercritical mobile phases and due to the often elevated analysis temperatures when using gaseous mobiles phases are extremely demanding in relation to the immobilized stationary phases placed on chemical and physical stability. So far this has been achieved on the one hand achieved the use of silica gels, whose surface silanol groups correspond with Reactive, chiral molecules was modified, and on the other hand by the Ein Set of naturally occurring chiral polymers (e.g. sugar, proteins) in derivatized or native form. Although these methods have found numerous uses, they are subject to severe methodological restrictions (e.g. use of the Carrier as a reaction partner, high and difficult to control proportion does not react ter surface silanols with a tendency to silanophilic interactions, large-pore or non-porous carrier materials are often not usable). An obvious goal  is therefore, the selector regardless of the presence chromatographically undesirable First chemically bind silanol groups to a fluid matrix and this chiral poly then apply to the carrier by covering.

The present invention was therefore based on the object of corresponding CHIRA SIL-DEX stationary phases with high stability without loss of selectivity on one Fixate carriers and this new procedure for the chromatographic separation of To use substances, especially enantiomers.

This object was achieved in that an alkenylated cyclodextrin Derivative by platinum-catalyzed hydrosilylation to a hydromethylsiloxy unit containing polymer was chemically bound. The chiral cyclodextrin thus obtained The stationary phase is achieved by introducing the carrier material into a solution of the polymer in dichloromethane and subsequent slow removal of the solvent occupies the carrier. The high washout resistance of the CHIRASIL-DEX stationary phase is in the last step by thermal treatment (typically 40 hours at 190 ° C) achieved in a high vacuum, whereby up to 80 percent immobilization is achieved. The mechanism of immobilization is still unknown. The presence of additional However, hydrosilane groups or traces of platinum metal catalyst appear to be the first to influence the cross-linking process positively. If silica gel is used as the carrier material applies, this can be extracted with Di chloromethane and methanol can be packed in a separation column of any geometry. The Packed separation columns produced in this way are suitable for chromatographic separation of substances using liquid and supercritical mobile phases. Even un ter use of mobile phases of high solvent strength (dichloromethane, Tetrahy drofuran) up to 50 ° C there was no loss of stationary phase after elution of over one observed a thousand column volumes. A low bleeding rate in the stationary phase is an essential prerequisite for the effective coupling of the inclusion chromato graph with spectroscopic methods in trace analysis.

Of particular note is the easy access to the cyclo immobilized according to the invention dextrin-containing polymers support materials.

The method of immobilizing cyclodextrin-containing poly according to the invention on other smooth or porous surfaces is also on those in the filtration, Detection and sensor technology usual carrier materials applicable. The follow the examples are intended to illustrate the invention, but without restricting it.

example 1

To prepare the olefinic cyclodextrin derivative in a 500 ml three neck flask with nitrogen inlet, dropping funnel and reflux condenser with mercury valve 10 g (8.83 mmol) of anhydrous β-cyclodextrin under nitrogen (48 h at 60 ° C. via Phos dried phosphorus oxide) dissolved in 225 ml of dry dimethyl sulfoxide. You add to that Add 1.8 g (45 mmol) of powdered sodium hydroxide cookies. The solution changes color yellow. After half an hour of vigorous stirring at room temperature, the solution clear. The mixture is left to stir for another hour and then 7.6 ml (45 mmol) are slowly added dropwise. 8-bromo-1-octene, dissolved in 30 ml of dry dimethyl sulfoxide. After 48 hours of reak tion time is filtered off from sodium bromide and sodium hydroxide and the solution until evaporated to dryness. The residue is taken up in 30 ml of methanol. Through the slowly adding a total of 150 ml of diethyl ether produces a whitish precipitate, which is quickly filtered through a Büchner funnel. By flash chromatography is separated from non alkenylated and overalkenylated products (eluent Toluene: ethanol 4: 1). The degree of substitution is determined by means of ion spray mass spectrometry of β-cyclodextrin determined. The crystalline monooktenylated product is at 60 ° C. and dried 0.05 torr overnight (yield: 7.1 g, 64% of theory). This pro product can now be derivatized in any way.

Example 2

If, for example, permethylation is to be carried out, 3.0 is carefully used g (125 mmol) sodium hydride in a four-necked flask with a nitrogen inlet, two drops funnels and reflux coolers with mercury valve are carefully under nitrogen a. One of the two dropping funnels then carefully becomes half of a solution of 3.0 g (2.4 mmol) of the product described in Example 1 in 100 ml of anhydrous Dimethylformamide added dropwise (hydrogen evolution!). Then you give over the second dropping funnel add half of 11.8 ml methyl iodide (188 mmol) so slowly that the temperature does not exceed 20 ° C. After stirring for one hour, be in the above Ordered the remaining solutions dropwise. After another hour, the Slowly poured the reaction mixture onto 300 ml of ice water. The aqueous solution becomes shaken three times with 100 ml of diethyl ether each and the combined diethyl ether phases back extracted three times with 20 ml of water to obtain most of the dimethylformamide to remove. After drying over sodium sulfate, the solvent is spun in. It a yellowish solid forms. Of under-methylated cyclodextrin derivatives  is purified by flash chromatography (eluent toluene: ethanol 4: 1).

The product is dried overnight at 60 ° C. and 0.05 Torr (yield: 1.3 g, 44 % of theory).

Example 3

The chiral polysiloxane is prepared from hydromethylpolysiloxane, to which ches by platinum-catalyzed hydrosilylation in a polymer-analogous reaction unsaturated β-diketone is chemically bound. The hydromethylpolysiloxane contains e.g. B. up to 25% hydromethyldisiloxy units at molecular weights up to 15000. The chemical structure of the substituents of the remaining monomer units of the hydro methylpolysiloxane can be varied within wide limits (e.g. alkyl, aryl, Perfluorinated residues, ionic groups). The use of block polymers or smek table phases with hydromethylsiloxy monomer units is also possible.

According to the invention, in a typical synthesis, for example, 3 g (1 mmol) (5%) Hydromethyl- (95%) dimethylpolysiloxane (MW about 3000) and 0.72 g of the in Permethyl-Monokis-6- (oct-7-enyl) -β-cyclodextrin (about 0.5 mmol) described in game 2, dissolved in 100 ml of absolute toluene, in a 250 ml three-necked flask with nitrogen inlet, Dropping funnel and reflux condenser with mercury valve introduced and under reflux heated. Then 1 ml of an approximately 0.1% solution of hexachloroplatinum (IV) is added. acid hexahydrate in absolute tetrahydrofuran (about 0.5 mg in 5 ml) to boiling Solution. After an hour, 1 ml of the catalyst solution is added and then the reaction solution was heated to reflux for 24 hours. After spinning off the toluene the residue is taken up in 50 ml of anhydrous methanol, the solution somewhat stirred and then decanted to free from unreacted cyclodextrin. Of the The residue is taken up in 10 ml of n-pentane, dropwise methanol is added, until the first catalyst-containing siloxane drops form. You decant and rotate the Methanol / n-pentane solution. This process is repeated if after Einro no transparent polysiloxane. The viscous, sometimes light brownish polysiloxane is dried overnight at 60 ° C. and 0.05 Torr (yield: 1.3 g, 34% of theory).

Example 4

For the production of carrier materials according to the invention which are immobilized with  CHIRASIL-DEX stationary phases are occupied, is solved according to the desired one Film thickness a certain amount z. B. the polymer obtained according to Example 3 in dry Dichloromethane (1:20 w / v) and slurried with 4 g silica gel (e.g. 5 µm, 300 Å Po ren size), which was previously dried by azeotropic distillation with toluene, in Ultrasonic bath on. Then the solvent is slowly turned on a rotary evaporator removed and the free-flowing, not glued silica gel coated with CHIRASIL-B-DEX Heated to 190 ° C in a high vacuum for 48 hours. Not immobilized CHIRASIL DEX is extracted with 200 ml methanol, dichloromethane and diethyl ether. For The percentage of carbon was calculated to calculate the degree of immobilization and hydrogen, determined by elemental analysis, before and after washing the silica gel coated with immobilized CHIRASIL-DEX used with the solvents. The immobilization rates are 70-80%.

With this material z. B. 10 or 25 cm long HPLC columns (4.6 mm in diameter) packed according to conventional methods in the slurry process. The HPLC columns are first with methanol, methanol / water (1: 1, v / v) and what rinsed. Further conditioning takes place with the respective buffer system a flow rate of 0.5 ml / min until a stable baseline is observed. Before storage, the columns are first covered with methanol / water (80/20, v / v) and then rinsed with methanol.

Example 5

On a 10 cm × 4.6 mm ID packed column produced according to Example 4 from 1.8 g of silica gel (20%, w / w) coated with immobilized CHIRASIL-DEX, z. B. the selective separation of the enantiomers of hexobarbital (see Fig. 1) using a 20 mM borate / phosphate buffer (pH 7.1 ml / min) which has been modified with various organic solvents. The resolution of the peaks of the separated enantiomers increases strongly with decreasing concentration and increasing polarity of the modifier. In Fig. 1 on the left side, methanol was used as a modifier in different concentrations. The resolution of the peaks increases with decreasing methanol concentration. If acetonitrile is used instead of methanol, the resolution of the enantiomers deteriorates considerably.

Claims (8)

1. Cyclodextrin-containing polymers (e.g. polysiloxanes, block polymers or smectic Phases) in which a chiral cyclodextrin derivative is chemically attached to a polymer chain is bound, and immobilized on smooth or porous surfaces of carrier materials be immobilized (immobilized CHIRASIL-DEX). 2. Immobilized cyclodextrin-containing polymers according to claim 1, which as chiral cyclo Contain dextrin component α-, β- or γ-Cydodextrindenvate. 3. Immobilized cyclodextrin-containing polymers according to claim 1 and 2, which from Cyclodextrin derivatives of α-, β-, or γ-cyclodextrin were produced that have an end constant double bond included. The remaining alcohol functions of each ver The olefinic cyclodextrins used are either in unchanged form or after any chemical change (e.g. alkylation, acylation, carbamoylation, Si lylation) used. 4. Immobilized, chiral polymers according to claims 1-3, which by hydrosilylation be chemically bound to a polymer containing hydromethylsiloxy units. 5. Chiral cyclodextrin-containing polymers according to claims 1-4, which by thermal loading action on the smooth or porous surface of carrier materials (e.g. silica gel), as they are generally used in the selective separation, detection and sensor technology of substances Find use, were immobilized. 6. Process for the chromatographic separation of isomers, isotopomers and ins special enantiomers as well as complex mixtures of active substances (e.g. Pherc mones, aromas, odorants, narcotics) by introducing the be in claims 1-4 wrote carrier materials modified with chiral cyclodextrin-containing polymers as stationary phases in separation columns using a liquid or supercritical Mobile phase. 7. Process for the separation of isomers, isotopomers and in particular of enantio mers as well as of complex mixtures by electroosmotic chromatography, as well the ultra or hyperfiltration, in which immobilized or non-extractable, chi rale cyclodextrin polymers according to claims 1-5 with prior application to a Carrier material can be used. 8. Method for the selective detection of isomers, isotopomers and in particular of enantiomers as well as of complex mixtures in which non-extractable, chi rale cyclodextrin polymers according to claims 1-5 with prior application to one Carrier (e.g. electrode or transistor surface) can be used.