# What is the difference between an alpha and beta carbohydrate?

Dec 16, 2016

They differ in the orientation of the $\text{OH}$ group at $\text{C-1}$.

#### Explanation:

When the straight-chain form of a carbohydrate like glucose closes to form a ring, it forms a new chiral centre at $\text{C-1}$.

This gives two different structures.

Their Haworth formulas are

Structure 1

and

Structure 2

To assign the α or β configurations to these forms, you look at the relative positions of $\text{C-6}$ and the $\text{OH}$ group on $\text{C-1}$.

In the α-form (Structure 1), the $\text{OH}$ group on $\text{C-1}$ is on the opposite side of the ring from $\text{C-6}$.

In the β-form (Structure 2), the $\text{OH}$ group on $\text{C-1}$ is on the same side of the ring as $\text{C-6}$.