There is described a process for the synthesis of a sucrose-6-ester comprising:
(a) reacting a mixture comprising sucrose and a polar aprotic solvent with an organotin-based
acylation promoter, while adding a solvent capable of removing water by co-distillation,
and removing water by co-distillation, to afford a first reaction mixture which
is substantially free from water, followed by (b) adding a carboxylic anhydride
to said first reaction mixture to afford a second reaction mixture, and maintaining
said second reaction mixture at a temperature and for a period of time sufficient
to produce a sucrose-6-ester, characterised in that step (a) is performed at a
temperature of from 85 to 125 C. and at a pressure of from 20 to 80 kPa.
In the most preferred embodiment, the polar aprotic solvent is DMF, the solvent
capable of removing water by co-distillation is cyclohexane, the organotion-based
acylation promoter is a 1,3-diacyloxy-1,1,3,3-tetrabutyldistannoxane, and step
(a) is performed at approximately 97 C., and approximately 50 kpa, until
the weight ratio of tin to water in the first reaction mixture is greater than
about 26, when the tin content is measured by X-Ray Fluoresence Analyzer, and the
water content is measured by the Karl-Fischer method.