Sucrose octaacetate


Sucrose octaacetate is a chemical compound with formula or, an eight-fold ester of sucrose and acetic acid. Its molecule can be described as that of sucrose with its eight hydroxyl groups – replaced by acetate groups –. It is a crystalline solid, colorless and odorless but intensely bitter.
Sucrose octaacetate is used as an inert ingredient in pesticides and herbicides, as a bitter additive.

History

The preparation of sucrose octaacetate was first described in 1865 by P. Schutzenberger, but its purification and characterization were first published by A. Herzfeld in 1887.

Preparation

The compound can be prepared by the exothermic reaction of sucrose with acetic anhydride at about 145 °C, with sodium acetate as catalyst.

Properties

Sucrose octaacetate is only slightly soluble in water but is soluble in many common organic solvents such as toluene and ethanol, from which it can be crystallized by evaporation. The crystalline form melts at 68–69 °C into a viscous liquid, that becomes a clear glassy solid on cooling.
The density of the glassy form is 1.28 kg;L, its index of refraction nD20 is 1.4660,its dielectric constant is 4.5, and its resistivity is 1.5 × 1014 Ω cm. It is optically active with D24 = +59.79°.
The compound slowly hydrolyzes in water: 0.25% of the acetate ester bonds were broken by boiling in water for 1 hour, and 0.20% after standing in water at 40° C for 5 days.
Sucrose octaacetate decomposes at about 285 °C, but can be distilled at reduced pressure at 260° C.
The compound is intensely bitter, being detectable at a concentration of 1–2 ppm.

Applications

It has a bitter taste which has led to its use as bitterant and an aversive agent. The chemical has also been used to determine tasters from non-tasters in mice.
While the crystalline character of the pure compound prevents its use as a plasticizer, this application is open to mixed esters where some acetate groups are replaced by propionate or isobutyrate.

Safety

Due to its low toxicity, sucrose octaacetate was authorized by the US Environment Protectio Agency for use as an inert ingredient in pesticides, as food additive, and as a nail-biting and thumb-sucking deterrent in over-the-counter drug products.