Carbohydrate Chemistry (5/13)

Carbohydrate isomers that differ in their orientation of their substituents at the anomeric carbon (mainly the hydroxyl group)

The carbon with the double bond to oxygen in its linear form. It is a solid electrophile making it a promising site for nucleophilic attack

Forms a hemiacetal

Forms a hemikatal (instead of a second bound to oxygen, it forms a bond with another R-group

Intermolecular attack to form a furanose

Intermolecular attack to form a pyranose

beta

alpha

alpha and beta can rapidly convert back and fourth

dehydration reaction

Hydration event. Water comes in and attaches, then is deprotonated to restore hydroxyl group

occurs between 140-165 degrees C amino acids in foods are reacting with certain carbohydrates happens faster under basic conditions

undergo a redox reactions and therefore lose electrons to become oxidized EX) aldehydes, non-aldose sugars that can be converted into aldoses, maltose and lactose (because they have a free anomeric carbon)

Cannot participate in a redox reaction

Act as oxidizing agents: Cu, Ag, Fe

When aqueous silver is added to a sugar and then forms a solid. Once it precipitates from a solution, it produces a visible silver film that looks like a mirror

When aqueous copper is added to sugar the solution start blue and if aldehyde is present, turns solution red

Adding aqueous copper to sugar and measured the amount of oxidizing agent (CuO)

All monosaccharides are reducing agents All ketoses tautomerize to aldoses and all aldoses are reducing agents Disaccharides are reducing agents if they have a free anomeric carbon Polysaccharides are usually non-reducing agents