UA 2258 then CV 12 at O'Hare
Denver → Chicago → Luxembourg
Timetable, Chicago time
22:46UA 2258 from Denver at the gate
14:55CV 12 to Luxembourg leaves the gate
16 h 09 apart on the timetable, overnight
CV 12 leaves 16 h 09 after UA 2258 arrives on the timetable: more than half a day, so not a connection we count.