AA 2124 then UA 771 at LAX
Chicago O'Hare → Los Angeles → Beijing
Timetable, Los Angeles time
11:26AA 2124 from Chicago O'Hare at the gate
23:35UA 771 to Beijing leaves the gate
12 h 09 apart on the timetable
UA 771 leaves 12 h 09 after AA 2124 arrives on the timetable: more than half a day, so not a connection we count.