M5: CARBOHYDRATES (Part 1)

Aldehydes and Ketones

Carbohydrates are derivatives of _______________

Pentose

Is a monosaccharide with five carbon atoms

150.13 g/mol

Molecular weight of Pentose

Hexose

Is a monosaccharide with six carbon atoms

180.156 g/mol

Molecular weight of Hexose

Condensation Reaction

Hexoses can form disaccharides like sucrose by a ____________ that makes a 1,6-glycosidic bond

Aldoses

Those monosaccharides that contain an aldehyde functional group

Ketoses

Those monosaccharides that contain a ketone functional group on the second carbon atom.

Glyceraldehyde

Simplest Aldose

Dihydroxyacetone

Simplest Ketose

Erythrose

Aldose

Threose

Aldose

Ribose

Aldopentoses

Arabinose

Aldopentoses

Xylose

Aldopentoses

Lyxose

Aldopentoses

Allose

Aldohexoses

Altrose

Aldohexoses

Glucose

Aldohexoses

Mannose

Aldohexoses

Gulose

Aldohexoses

Idose

Aldohexoses

Galactose

Aldohexoses

Talose

Aldohexoses

Erythrulose

Ketoses

Ribulose

Ketopentoses

Xylulose

Ketopentoses

Psicose

Ketohexoses

Fructose

Ketohexoses

Sorbose

Ketohexoses

Tagatose

Ketohexoses

Monosaccharides, Disaccharides (Maltose & Lactose)

Reducing Sugars

Sucrose, Polysaccharides

Non-Reducing Sugars

Reducing Sugars

Are carbohydrates that serve as reducing agents due to their free aldehyde or ketone functional groups in their molecular structure. (Sugars with free anomeric carbon)

Non-Reducing Sugars

Do not have an OH group attached to the anomeric carbon so they cannot reduce other compounds. These sugars cannot donate electrons to other molecules and therefore cannot act as a reducing agent.

Molisch’s Test

A general test for all Carbohydrates, either free or bound to proteins or lipids. Trioses and Tetroses do not have the necessary five carbon atoms for furfural formation, so they do not give a positive result for this reaction. (Monosaccharides give a rapid positive test, while Disaccharides & Polysaccharides react slower)

Violet Ring at the junction; Presence of Carbohydrate

Molisch’s Test positive result

Bial’s Orcinol Test

[+] Blue-green solution; Presence of Pentose

Mucic Acid Test

[+] White Crystals; Presence of Galactose

Seliwanoff’s Test

[+] Cherry red solution; Presence of Ketose sugar

Osazone Test

[+] Characteristic Osazone crystals; Presence of Reducing sugar

Fructose (Osazone Test)

[+] Yellow needle-shaped haystack/ Broomstick crystals

Glucose

[+] Yellow needle-shaped haystack/ Broomstick crystals

Galactose (Osazone Test)

[+] Yellow Broken-glass like crystals

Lactose (Osazone Test)

[+] Yellow badminton ball-shaped crystals

Maltose (Osazone Test)

[+] Yellow star-shaped crystals

Ribose (Osazone Test)

[+] Yellow star-shaped crystals

Xylose (Osazone Test)

[+] Yellow flower-shaped crystals

Arabinose (Osazone Test)

[+] Yellow spider-shaped crystals