What is the difference between an alpha and beta carbohydrate?

Question

7889 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-12-16T23:10:40

They differ in the orientation of the #"OH"# group at #"C-1"#.

When the straight-chain form of a carbohydrate like glucose closes to form a ring, it forms a new chiral centre at #"C-1"#.

This gives two different structures.

Their Haworth formulas are

www.bio.miami.edu
Structure 1

and

www.bio.miami.edu
Structure 2

To assign the α or β configurations to these forms, you look at the relative positions of #"C-6"# and the #"OH"# group on #"C-1"#.

In the α-form (Structure 1), the #"OH"# group on #"C-1"# is on the opposite side of the ring from #"C-6"#.

In the β-form (Structure 2), the #"OH"# group on #"C-1"# is on the same side of the ring as #"C-6"#.