Does vinegar dissipate with cooking? How much?
Short answer: not really.
Vinegar is about 5% acetic acid (the "vinegary" tasting substance) and about 95% inert ingredients, mostly water. When you cook down vinegar, you are mostly evaporating that water.
There are probably certain specific and complicated situations in which vinegar dissipates a bit, but the rule of thumb is that once you add vinegar to a dish/preparation, it is not going away. A cautious cook will think of it as a spice or condiment like pepper, salt, etc. and will be judicious about its application.
Thanks. I was hoping to tell someone who was concerned about the adverse effects of vinegar that it probably mostly gets cooked away in the baking process. But sounds like it does not.