This map shows you how far you can travel in Europe in 5 hours by train: chronotrains.com
A first test showed that you can get from Zurich to Bologna. The SBB timetable comes up with a travel time of 5h and 36min. In Milano Centrale, however, you have to wait 45min for the connection, which is why the total time on the train is only 4h 51min.
By the way: The C02 emission per passenger for this train route is 15kg. With Twiliner it would be 9.5kg.