Tate & Lyle Public Limited Company

Tate & Lyle Public Ltd. Co.

Tate & Lyle, Inc.

George H Sankey

Philip J Simpson

Nigel J Homer

Graham Jackson

Riaz A Khan

Nicholas M Vernon

Solid sucralose

A method is provided for the preparation of a sucrose 6-ester by: (i) reacting a solution of sucrose in an inert organic solvent with a reagent selected from the group consisting of a trialkyl orthoester and a ketene acetal, in the presence of an acid catalyst to provide a sucrose alkyl 4,6-orthoester, (ii) treating the sucrose alkyl 4,6-orthoester under mild aqueous acidic conditions to provide a mixture of sucrose 4- and 6-monoesters, (iii) treating the mixture of esters with a base to convert the sucrose 4-ester into sucrose 6-ester, and (iv) neutralizing the solution and isolating the sucrose 6-ester, in which stage (i) is effected in a continuous manner by passing the solution of sucrose and reagent through a strong acid macroreticular ion exchange resin at ambient temperature. Sucralose is prepared by chlorinating the sucrose 6-esters obtained.

Continuous process for the preparation of sucrose 6-esters

A process for the chlorination of sucrose or a derivative thereof, comprises reaction of the sucrose or derivative thereof with thionyl chloride and a nitrogen base at a ratio of about 1 molar equivalent (ME) of thionyl chloride and about 1 ME of base for every ME of free hydroxyl, in a non-reactive moderately polar solvent. The process is particularly suitable for the preparation of sucralose.

Chlorination of sugars

Sugars and partly protected sugar derivatives are chlorinated by reaction of unprotected hydroxyl groups with thionyl chloride to form a persulphite followed by decomposition of the sulphite groups to form chlorosulphites, displacement of the chlorosulphite groups and insertion of chlorine atoms at one or more positions, characterised in that formation and displacement of the chlorosulphite groups and insertion of chlorine atoms is effected by reaction with thionyl chloride in an inert solvent in the presence of a quaternary salt of the general formula:

Process for the chlorination of sugars

2,3,4,3',4'-penta-O-acetyl sucrose (4-PAS), a key intermediate in the preparation of sucralose, is prepared by the selective removal of trityl groups from 6,1', 6'-tri-O-trityl-penta-O-acetyl sucrose (TRISPA) in which a catalytic amount of an aralkyl chloride or hydrogen chloride is added to a solution of TRISPA is an inert organic solvent is hydrogenated in the presence of a hydrogenolysis catalyst such a platinum or palladium.

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Reading, United Kingdom

George H Sankey