I was curious about this, so I looked it up. I was wrong about a motion to adjourn.
A motion to adjourn is almost always a "privileged" motion, so it can interrupt debate of other motions.
RRoO says:
- it is not applied to any motion, and cannot be applied to (as in, these are not allowed: I move to amend the current motion, and add a motion to adjourn, or I move to amend the motion to adjourn to also approve...)
- it is out of order when another has the floor
- must be seconded
- is not debatable
- is not amendable
- requires a majority vote
- cannot be reconsidered
(from RRoO, 10th edition, p. 228)
... just in case you were curious.
Eric.