Transesterification of Sucrose in Organic Medium: Study of Acyl Group Migrations

Abstract

The tendency of the acyl groups located on the glucose part of sucrose fatty acid esters to undergo intramolecular migrations in organic medium and the regioselectivity of some transesterifications of sucrose were investigated by HPLC, in situ NMR spectroscopy and preparative methods. Extensive acylation on secondary positions of the glucose moiety followed by migrations is general for base catalysed transesterification. The stability of 3‐ and 6‐O‐acyl derivatives, two isomers being thermodynamically favored compared to others, was studied in a series of conditions. It is shown that the presence of water catalyzes the migration of the ester at OH‐3 towards OH‐6 in organic basic medium, whereas the ester at OH‐6 appears more stable under either acidic or basic conditions.

^†This paper is dedicated to Professor Gérard Descotes on the occasion of his 70th birthday, in acknowledgement of his accomplishments in the field of carbohydrate chemistry, and of his continuing efforts for developing the use of renewable sugars for chemistry.

Keywords:

• Sucrose
• Regioselective esterification
• Acyl group migration
• In situ NMR

Acknowledgments

Financial support from the CNRS and Béghin‐Say is greatly acknowledged. We thank Béghin‐Say and l'Agence Nationale de la Recherche et de la Technologie for a grant to VM (contrat CIFRE).

Notes

^†This paper is dedicated to Professor Gérard Descotes on the occasion of his 70th birthday, in acknowledgement of his accomplishments in the field of carbohydrate chemistry, and of his continuing efforts for developing the use of renewable sugars for chemistry.

^aFor reviews in the field of the use of carbohydrates as chemicals, see Refs. 1-4.