B6 724 then DL 5704 at Boston
Santiago (Dominican Republic) → Boston → Washington National
Timetable, Boston time
08:59B6 724 from Santiago (Dominican Republic) at the gate
21:45DL 5704 to Washington National leaves the gate
12 h 46 apart on the timetable
DL 5704 leaves 12 h 46 after B6 724 arrives on the timetable: more than half a day, so not a connection we count.