Chapter 16 Pyrolysis of Carbohydrates

Carbohydrates (saccharides or sugars) are organic compounds containing one or more carbonyl groups in their molecules and two or more alcohol groups on an aliphatic hydrocarbon chain. These compounds can be classified as monosaccharides, oligosaccharides, and polysaccharides. The oligosaccharides and polysaccharides are generated by the elimination of water from two or more monosaccharide molecules, the sugar units being connected by an ether group. Glyceraldehyde and dihydroxyacetone (n=3) can be considered the simplest monosaccharides. The chapter describes pyrolysis of monosaccharides with less than six carbon atoms and glucose. The programs of two other hexoses, mannose, and galactose that are found mainly in pyranose form are given in the chapter. The pyrolysis and the programs were obtained in identical conditions as for glucose, at 900°C. Fructose is a hexose that is found mainly in furanose form. The pyrolysis products of fructose are similar in nature with those of other monosaccharides. Disaccharides are formed by the elimination of a water molecule between two monosaccharides (different or identical) with the formation of an ether bond. Pyrolysis of disaccharides takes place following reactions very similar to those of monosaccharides. The nature of pyrolysis products from a disaccharide depends on the nature of the component monosaccharides and on the type of connection between the two monosaccharide molecules. Pyrolysis of three disaccharides—maltose, lactose, and sucrose—was performed in identical conditions as for glucose and the programs. Pyrolysis of three disaccharides—maltose, lactose, and sucrose—was performed in identical conditions as for glucose. A large variety of compounds are derived from carbohydrates. These compounds are generated by the modification of the initial carbohydrate molecule, either adding or subtracting functionalities. Several of the more common carbohydrate derivatives are given in the chapter.