1.12 Reactions of Monosaccharides

• 5 important reactions of monosaccharides:

  • Oxidation to acidic sugars 
  • Reduction to sugar alcohols 
  • Glycoside formation
  • Phosphate ester formation 
  • Amino sugar formation
• Oxidation

  • +oxygen
  • -electrons
• Reduction

  • -oxygen
  • +electrons
• Oxidation can yield 3 different types of acidic sugars depending on the type of oxidizing agent used:

  1. Aldonic acid
  2. Reducing sugar
• Aldonic acid

  • Acidic sugar formed when weak oxidizing agents oxidize the aldehyde end.
• Reducing sugar

  • Carbohydrate that gives a positive test with Tollens and Benedict’s solutions.
• In biochemical systems, enzymes can oxidize the primary alcohol end of an aldose such as glucose, without oxidation of the aldehyde group, to produce an alduronic acid
• Sorbitol

  • Used as a moisturizing agent in foods and cosmetics and as a sweetening agent in chewing gum.
• Glycoside

  • Acetal formed from a cyclic monosaccharide by replacement of the hemiacetal carbon –OH group with an –OR group 
• Glucoside

  • Glycoside produced from glucose
• Galactoside

  • Glycoside produced from galactose
• Amino sugar

  • Formed when one of the hydroxyl groups of a monosaccharide is replaced with an amino group.