What is the reaction of ammonium nitrate with hypochlorous acid
Do not for goodness sake mix chlorine bleach with ammonium compounds or ammonia, it has a good chance of ending badly.

I am not sure of the curved arrow mechanism, but what I suspect will happen is that the ammonia will attack the HO-Cl using the OH- as a leaving group. So by making the system less basic it will favour the reaction.

This will convert ammonia into NH2Cl, which will then be converted into NHCl2 and finally into nitrogen trichloride (NCl3). When I was a PhD student one of the other people has to make NCl3, he did it with great care. He did the reaction in such a way that the NCl3 was diluted in an inert solvent.

The scary thing about nitrogen trichloride is that it is a very unstable and shock sensitive explosive. One of my uncles is a chemist like me, he once witnessed an accident in which a man lost several fingers playing around with nitrogen iodide.

But back to nitrogen trichloride, as well as being explosive it is also a harmful and irritating substance. I would suggest you have nothing to do with it !