Chapter 25 : Carbohydrates

• We first discussed cyclic compounds in Chapter 3.
• One of the important conclusions was that 5- and 6- membered rings were more favourable because they were comparatively "strain free"
• As a result, 5- and 6-membered rings are quite common, especially in naturally occuring molecules.
• Cyclic sugars that contain a five membered ring are called "furanoses".
• The term is derived from the similarity with the aromatic compound furan and tetrahydrofuran.
• Cyclic sugars that contain a six membered ring are called "pyranoses"
• The term is derived from the similarity with the compound pyran and tetrahydropyran.

 

Compound Name	Line Drawing	3D Model	Compound Name	Line Drawing	3D Model
Tetrahydrofuran			Furan
Tetrahydropyran			Pyran

 

Classification	Example	Line Drawing	3D Model
Furanose	Fructose
Pyranose	b-D-glucose

© Dr. Ian Hunt, Department of Chemistry