My question is in regards to acid base reaction that take place in larger chemical reaction in orgo. Like, I understand acid base reaction, how to qualitatively check which is stronger acid or base or where equilibrium lies, very well. But i feel that when I am trying to study the mechanism of series of other reaction like grignard mechanism, oxidation of alcohol, reaction with aldehydes etc… I see many intermediate acid base reaction in these mechanism that don’t make sense in terms of what I learned earlier when I was exclusively studying acid base reaction.
For instance, I have seen many intermediate acid base reaction in larger reaction where an oxygen atom of one molecule attack H atom attached to oxygen atom in another molecule. And then I am thinking what the point of this reaction because equilibrium is gonna be in middle and not favor products since the conjugate base create will be acid right away anyways.
Other times I have seen H20 act as an acid while molecule with sulfur atom act as a base. And again I am thinking how this is possible because isn’t sulfur a stronger acid then water. When I asked two of my teacher about this. One of them said she actually made a mistake. But the main professor actually said that she is correct and to explain this, she said that water would even be hydronium ion here and when there is lot of water around, this water can serve as acid. However I couldn't fully understand what she meant by that? Can anyone please explain what she meant by this or how these acid base reaction possible. I have attached picture of what I am mean below to explain it my problem more clearly.