Methylation of cyclodextrins by phase-transfer catalysis

Autor: L. Szente, L. Tőke, Péter Bakó, László Fenichel, J. Szejtli
Rok vydání: 1994
Předmět:
Zdroj: Journal of Inclusion Phenomena and Molecular Recognition in Chemistry. 18:307-314
ISSN: 1573-1111
0923-0750
DOI: 10.1007/bf00708737
Popis: A new, simple method has been developed for the methylation of cyclodextrins. The reaction proceeds in the heterogeneous phase with dimethyl sulphate, using a solvent in which the original cyclodextrins and the bases used are poorly soluble or insoluble. However, in the presence of phase transfer catalysts, methylation proceeds with good yields. The products are mixtures of randomly methylated cyclodextrins (RAMEB), containing 60–70% of heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB), 10–15% of heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB) and some monomethylated isomers. These methylated products have proved to be excellent detergents; e.g., they are able to significantly increase the water solubility of hydrocortisone, methyltesterone, etc. On repeating methylation twice, the amount of TRIMEB increases, and a pure product (28% yield) can be obtained by crystallisation.
Databáze: OpenAIRE
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