can't open iTunes version 11.4

I have a MacBook Pro running OS 10.6.8. I rarely use iTunes but I just upgraded to iTunes 11.4. Now the app won't open at all. I apparently have to upgrade the operating system to download the newest iTunes version (12.1). OS 10.6.8 is working fine for me and I'd rather not download a new OS.

Can I un-install iTunes 11.4 and re-install the older version? Where would I find a version of iTunes compatible with my OS? I don't remember the version of iTunes that I had.

Thank you for your time.