We have just bought an apt and would like to add a half bath, where the kitchen is now. Is this possible? The main bath is far. There is only a sink where we would like to place the toilet

There is only a sink where we would like to place the toilet Is this possible?
Anything's possible with enough money. And you're going to spend big bucks just getting a 3" main over from the first bath over to where you want to install the new one. That plus the cost of installation. A lot will depend on what floor your unit is on. If your on a slab you can jackhammer up the slab and run a main over to the kitchen. However, if you have a upper unit this remodel would greatly impact the downstairs unit.
Once you get the main over there here's how you'll hook everything up, (see image) Good luck with your project. Tom