While this ticket is within MCT, under the subjective circumstances, it is well outside SCT (Sensible Connection Time). UA will rebook on the next available flight to SNA, but there are only three such nonstop flights per day. In addition, UA might offer to send you to LAX or SAN if you wished, but that would be up to you.
The complicating factor here is the wheelchair. ORD is a huge airport and UA is its largest carrier. As others note, the time between gates walking at a good clip can be as much as 15 minutes. A wheelchair may complicate and delay that.
Only you know the specifics of your daughter's disability and what that means in terms of a wheelchair, but I would call UA and ask them to change your flights so that you have a good solid 2-3 hours on the ground at ORD. Make certain that your daughter's needs are already in the PNR notes and that you make reference to this when you call. This builds in time for some delays and means that the stress is removed from the trip.