AA 642 then UA 4765 at O'Hare
Dallas-Fort Worth → Chicago → Des Moines
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
12:55UA 4765 to Des Moines leaves the gate
23 h 45 apart on the timetable, overnight
UA 4765 leaves 23 h 45 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.