The dehydration of sucrose

By 2007-03-01T00:00:00

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Source: Colin Baker

Create a smoking column of carbon

Sucrose is a disaccharide with the formula C12H22O11. On hydrolysis, it yields the two monosaccharides, glucose (aldohexose) and fructose (ketohexose), and on dehydration produces a complex carbonaceous solid residue.  

The reaction between sucrose and concentrated H2SO4

With this reaction, there is a time delay of almost one minute before the reaction proceeds. The acid starts to go yellow as the dehydration begins. The rate of dehydration then accelerates as the acid heats up because the reaction is exothermic. As the sugar molecules are stripped of water, the heat generated turns the water into steam which then expands the remaining carbon into a porous, smoking, black column. This expands out of the reaction vessel, producing a choking acrid vapour and the smell of burned sugar.

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