Properties of cyclodextrins. IV. Features and use of insoluble cyclodextrin-epichlorohydrin resins

Cyclodextrin-epichlorohydrin resins, prepd. by crosslinking a-cyclodextrin or b-cyclodextrin (I) with 10-25% epichlorohydrin (II), gave results comparable with those obtained with Sephadex G-25 coarse when both resins were used for gel chromatog., i.e., designated as gel inclusion chromatog. because cyclodextrin voids form inclusion compds. of different stabilities with the substances to be sepd. A 17:3 I-II resin had slightly greater thermal stability than the Sephadex G-25. The elution vols. on a column of 3:1 I-II resin eluted with 20 vol. % aq. EtOH were as follows (compd., elution vol. in ml. for the I-II resin and Sephadex G-25, resp., given): glyceryl L-tyrosine, 142, 120; DL-benzoylalanine, 47, 60; salicine, 104, 110; L-tyrosine HCl 105, 135; DL-tryptophan HCl, 207, 208; aniline HCl, 511, 150; BzOH, 400, 100; phenol, does not leave the column, 133; o-chlorobenzoic acid, 98, 83; m-chlorobenzoic acid, 400, 83; dextran blue, 40, 55. The behavior of resins contg. I differs from that of resins contg. a-cyclodextrin because the void sizes are different. [on SciFinder (R)

Thin-layer chromatography of cyclodextrins and some other sugars using micro-chromatoplates

The a- (I) and b-cyclodextrins (II) were sepd. on micro-chromatoplates (Peifer, CA 57, 1511g). Adsorbents were Kiesel-G \"Merck\" (A) and Alusil layers (B) (25 g. each A and Al2O3-G \"Merck\" in 2:1 CHCl3-MeOH). The best solvents were 6:3:1:2:4 BuOH-HOAc-H2O-C5H5N-HCONMe2 (C) and 6:3:1 BuOH-HOAc-H2O (D). The indicator spray was a mixt. of 10 ml. H2SO4, 20 ml. H2O, and 3 g. K2Cr2O7. The Rf values of I and II, resp., on A with C are 0.0 and 0.5; similar values are found on B with C, but the spots are less sharp. I, II, glucose, and maltose were sepd. on A by development first with solvent D, allowing D to reach the end of the adsorbent, letting stand 4 min., vaporization of D, then development with solvent C

Determination of water in cyclodextrins by a gaschromatographic method

The H2O content of b-cyclodextrin (0.1-10% by wt.) was detd. by gas chromatog. The b-cyclodextrin is dissolved in dry HCONMe2 and chromatographed on a column of Porapak P; one detn. can be made per hr. with a relative accuracy of 4%. The results are in good agreement with those obtained by oven-drying. [on SciFinder (R)

Properties of cyclodextrins. II. Preparation of a stable β-cyclodextrin hydrate and determination of its water content and enthalpy of solution in water from 15 to 30.deg

The solubility of ß-cyclodextrin (ß-CD) in water has been measured by a refractive-index method at 15–30°. Evidence was obtained that the same, solid ß-CD hydrate phase is present in this temperature range. The formula of the hydrate was shown to be C42H70O35(12.0 ± 0.5)H20. A method for preparation of this ß-CD hydrate is described. The relations between refractive index and concentration of ß-CD are given. The calculated enthalpy of solution ¿H50l = 7.094 ±0.021 kcal. mole-1. This value will only slightly be influenced by the number of moles of water per mole of ß-CD in the hydrated solid. The solubility of ß-CD as a function of temperature can be described by 2.303 log10 m = (3.88±0.02) - (3583±18)/T where m = mole fraction of anhydrous ß-CD at saturation, and T = absolute temperature

Properties of cyclodextrins. V. Inclusion isotherm and kinetics of inclusion of benzoic acid and m-chlorobenzoic acid on b-E 25 cyclodextrin-epichlorohydrin resin

The previous paper showed that b-E 25 resins have an affinity for aromatic compds., e.g. BZOH and m-ClC6H4CO2H; mainly the undissocd. acids are involved. The isothermal inclusion of undissocd. BZOH is described by a Langmuir isotherm, but that of m-ClC6H4CO2H follows a Freundlich isotherm. The kinetics of sorption of both acids are very complicated. At least 3 kinetic mechanisms are involved. [on SciFinder (R)

Properties of cyclodextrins. III. Cyclodextrin-epichlorhydrin resins. Preparation and analysis

A bead polymn. process was used to prepare resins in a form useful for packing chromatographic columns from a-cyclodextrin (I) or b-cyclodextrin (II) and epichlorohydrin (III). A soln. of 2 ml. nonionic detergent (Nonidet P40) in 10 ml. o-xylene was added to 350 ml. o-xylene at 80 Deg , stirred 2 min., and mixed with a soln. prepd. by dissolving 9 g. finely powdered I in a mixt. of 5 g. water, 16 g. 30% NaOH, and 20 mg. NaBH4 at 30 Deg. After 5 min. vigorous stirring, 25 g. III was added. Beads formed in 30 min. The beads were then suspended in 100 ml. 1:1 vol. EtOH-water for 10 min., freed of excess liq., and suspended 30 min. in 96% EtOH. This procedure was repeated 2 times, and the beads were then dried 18 hrs. at 70 Deg. The bead polymn. of II was carried out similarly, using iso-BuCOMe instead of o-xylene solvent. Water-sol. resins were also prepd. by stirring the polymn. mixt. gently and omitting the surfactant. The apparent void concn. in the resins was detd. either by cleaving the a,1 -> 4 linkages by acid hydrolysis and then detg. the reducing groups liberated, or by utilizing the ability of cyclodextrin voids to form a sol. inclusion compd. with m-chlorobenzoic acid. The amt. of inclusion compd. was detd. spectrophotometrically and the apparent void concn. was read from a calibration curve. The results of degree of substitution calcns. indicated that the resins contained at least some polyoxyethene chains. [on SciFinder (R)