Question

What OH groups are axial in β-D-altropyranose? Having a lot of trouble drawing the compound in chair and boat conformation.

It looks like none of the OH groups are in axial position and all are equatorial. I have found several different drawings of this compound and have become very confused.

Answer 1

Here's how I work it out.

Explanation:

The structures of D-altrose and D-Glucose are

(Adapted from Chemistry - Tutorvista.com)

The configuration of D-altrose differs from that of D-glucose at carbons 2 and 3.

In β-D-glucopyranose, all `"OH"` groups are equatorial.

Thus, in β-d-altropyranose, the `"OH"` groups on carbons 2 and 3 are axial.

I couldn't find an image of the molecule, so I drew the one below, omitting all H atoms except those on the ring.

The `"OH"` groups on carbons 2 and 3 are axial. The others are equatorial.