Ketoses

Ketoses, sugars containing a ketone group -CO- (ketosugars). Unlike aldoses (see), ketoses upon oxidation break down to form a mixture of oxyacids having a shorter carbon chain. A characteristic reaction of ketoses is the red coloration when boiled with resorcinol and HCl, the so-called Selivanov reaction (see). Artificially, ketoses can be obtained by the biological oxidation of corresponding polyhydric alcohols by a special microbe—the bacterium sorbose. Of ketoses found in nature are dihydroxyacetone, CH₂OH.CO.CH₂OH—a ketotriose, to which some authors attribute the role of an intermediate link in fermentation and in the oxidation of carbohydrates in the body; fructose (see)—a ketohexose, widely distributed in living nature in free form and as part of polysaccharides and glycosides; sorbose—a ketohexose, found in the fruits of rowan. In addition, other ketoses, unknown in nature, have been obtained synthetically. (See also Hexoses, Carbohydrates, Carbohydrate metabolism.)