Analysis of cyclodextrin mixtures by gas chromatography of their dimethylsilyl ethers

Beadle, Joan.

doi:10.1016/s0021-9673(01)80616-6

Cited by 14 publications

(5 citation statements)

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“…Silyl ethers of cyclodextrins are widely investigated because silyl groups are good protecting groups due to their ease of removal. ,, TBDMS is relatively more selective in pyridine or DMF at room temperature and proceeds to mostly the 6-positions whereas at higher temperature it starts reacting with the secondary side of cyclodextrins . Trimethylsilyl chloride (TMSCl) is less discriminatory than TBDMSCl and attacks all three positions of cyclodextrins in pyridine at room temperature. , …”

Section: 4 Persubstitution At the 6-position Of Cyclodextrinsmentioning

confidence: 99%

“…Complete silylation at all three positions is possible with trimethylsilyl chloride, although this reaction has little synthetic utility. ,, Silylation of cyclodextrins greatly enhances their solubility in various organic solvents. Cyclodextrins which have been selectively persilylated at either the primary or the secondary face are extensively used to attach desired groups at the free hydroxyl groups.…”

Section: Permodification At All Three Positions Of Cyclodextrinsmentioning

confidence: 99%

“…158 Trimethylsilyl chloride (TMSCl) is less discriminatory than TBDMSCl and attacks all three positions of cyclodextrins in pyridine at room temperature. 18,160 Perazidocyclodextrins are obtained from per-6mesitylated cyclodextrins and sodium azide in DMF in 92% yield. 161 In early reports, they are synthesized by reacting the per-6-sulfonate with the azide salt in DMF.…”

Section: Persubstitution At the 6-position Of Cyclodextrinsmentioning

confidence: 99%

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Methods for Selective Modifications of Cyclodextrins

et al. 1998

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be established before the mechanistic information about the artificial enzyme can be reliably derived. Scope of This ReviewIn this review, we present a systematic analysis of methods that are available for modification of cyclodextrins. The focus is on methods for transformation where the number and the exact positions of modifications are ascertained and pure compounds with unambiguous structures are obtained. In cases where the products have unusual and interesting properties, these attributes are mentioned. We have not attempted to cite every cyclodextrin derivative that has been made. This has already been achieved in an excellent and recent review. 12 We have also not included modified cyclodextrins obtained by purely synthetic routes, i.e., strategies to obtain these molecules from appropriately derivatized monosaccharides rather than cyclodextrins. A recent review describes strategies for the preparation of synthetic cyclic oligosacharides. 7 An Overview of Methods for Modification of CyclodextrinsMethods for selective modification of cyclodextrin can be divided into three categories: (1) the "clever"

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Section: 4 Persubstitution At the 6-position Of Cyclodextrinsmentioning

confidence: 99%

Section: Permodification At All Three Positions Of Cyclodextrinsmentioning

confidence: 99%

Section: Persubstitution At the 6-position Of Cyclodextrinsmentioning

confidence: 99%

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Methods for Selective Modifications of Cyclodextrins

et al. 1998

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“…The maximum radioactivity was detected in the first two hours with labelled glucose and starch but only between the fourth and eighth hours with labelled ~-cyclodextrin [ 94 J. <Figure [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

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Cyclodextrins

Szejtli

1988

Topics in Inclusion Science

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Enzymic degradation of starch generally results in the production of glucose, maltose, maltotriose, etc., Le. a long series of linear or branched chain malto-oligomers, known as dextrins.Dextrins are heterogeneous, amorphous, hygroscopic substances, produced in large quantities for the food, textile, paper and other industries. They are also consumed without prior isolation in such products as e.g. beer and bread. This type of starch degradation is a true hydrolytic process, as the primary product from the splitting of the glycosidic linkage reacts with one molecule of water.If however, the starch is degraded by the glucosyltransferase enzyme (CGT), the primary product of the chain splitting undergoes an intramolecular reaction without the participation of a water molecule. The ex-1,4-linked cyclic products are formed; they are known as cyclodextrins (Figure 1-1). a-AMYLASE ~ .. ~ C> C> c:> J. Szejtli, Cyclodextrin Technology © Springer Science+Business Media Dordrecht 1988 CYCLODEXTRIN TECHNOLOGY APOLAR CAVITY SECONDARY HYDROXYLS ~PRIMARY HYDROXYLS Fig .1-6. Functional structural scheme of cyc1odextrins.making it a rigid structure. This is the probable explanation for the observation that ~-cyclodextrin has the lowest solubility of all the cyclodex trins. The hydrogen-bond belt is incomplete in the a-cyclodextrin molecule, as one glucopyranose unit is in a distorted position [ 301,304 J. As a consequence only four of the six possible H-bonds can be established. The y-cyclodextrin is a non-coplanar, more flexible structure, and is therefore the more soluble of the three. Equilibrium constants for the hydrogendeuterium exchange in the secondary hydroxyls (0.65 for 6-cyclodextrin, 0.75 for a-cyclodextrin and 0.85 for amylose) indicate the strongest H-bond system to be in ~-cyclodextrin [ 51 J.According to conformation-energy maps [ 325 J, hydrogen bonding between the C2 and C3 hydroxyls results in a lowering of energy by 20 kcal/mole (83.7 kJ/mole) in a-cyclodextrin, and of 30 kcal/mole (125 kJ/mole) in ~-cyclodextrin. J'2 J 23 J 34 J 45 J 56 .. J 561> J s .. , 0$1>

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“…Even a change in ionic strength or temperature may disturb the facile equilibrium of complexation. Chromatographic CD assays have also been used (Beadle, 1969;Takeo and Kondo, 1970; Nakamura and Horikoshi 1976; Zsadon et al, 1978;Zsadon et al, 1979). They are often time-consuming and so less suitable to large series of samples.…”

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confidence: 99%

Nonchromatographic cyclodextrin assays: evaluation of sensitivity, specificity, and conversion mixture applications

Mäkelä¹,

Korpela²,

Puisto³

et al. 1988

J. Agric. Food Chem.

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Methods based on various clathrate-forming molecules, siigar analyses in combination with glucoamylase treatment, or catalytic properties of cyclodextrins were evaluated as cyclodextrin assays. Optimum conditions for the assays were determined and, when necessary, appropriate modifications were made. The tests were made by using pure cyclodextrin standards, supplemented standards, and conversion mixtures obtained by the action of cyclodextrin glycosyltransferase on starch. The optimized methods varied considerably with respect to measurement range, relative sensitivity toward CY-, p-, and 7-cyclodextrin, and susceptibility to interferences. On the basis of data from these experiments, typical applications of individual methods or their combinations are suggested. The specificity differences of assays based on methylorange, bromocresol green, and phenolphthalein were found especially useful in the analysis of individual CDs out of their mixtures. An example of the usage of this method combination is given.

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Analysis of cyclodextrin mixtures by gas chromatography of their dimethylsilyl ethers

Cited by 14 publications

References 4 publications

Methods for Selective Modifications of Cyclodextrins

Methods for Selective Modifications of Cyclodextrins

Cyclodextrins

Nonchromatographic cyclodextrin assays: evaluation of sensitivity, specificity, and conversion mixture applications

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