if you want vinegar you need
1. ethanol, so you need to ferment the apple juice. acetobacter turn ethanol to acetic acid. if you leave your cider out for a year first yeasts will ferment the sugar to ethanol, then acetobacter get to work.
2. acetobacter, which is in the air, or can be added from another homemade vinegar. but it can find its way in without too much trouble.
3. oxygen, so shake it, pour it, swish it, whisk it. then cover with cloth and leave it for a few months. i think commercial vinegar producers bubble oxygen gas through the cider/wine/whatever.
it doesn't matter if it was pasteurized but additives like sulfites will probably inhibit acetobacter by reacting with free oxygen. i'm not a great chemist. don't know about sorbate. now- get drunk. or in this case, have a tangy salad