Question

What is an equatorial substituent?

Answer 1

Do you have an example? It may be easier to explain that than to give you something to read. I was unable to find anything on the net that I thought was appropriate.

Answer 2

This is a substitute (usually a functional group) in the pane of the ring as opposed to axial which is perpendicular to the ring. The terminology is usually used for cyclohexanes in the chair form, but is also for rings systems on the diamond lattice such as cyclododecanes.

The usual example quoted when teaching is glucose where all the substituents (OH groups) are in the plane of the ring, i.e. equatorial.

Hope this helps.