For each reaction below, draw the mechanism (curved arrows) and then predict which side of the reaction is favored under equilibrium conditions.
Alright, so let's go ahead and figure out an arrow pushing mechanism for this reaction. So, here we start off with, wait a minute, guys if you notice this looks really similar, right? This looks so very familiar, right? It looks something like just a carboxylic acid where all the oxygens are just replaced with sulfur, right? Which is exactly what's happening in all of this, right? This is-, this looks like a hydroxide almost, right? So, it's HO negative would be the equivalent. So guys, all that's really happening here is that we're going from standard pKa values, right? We can just think about it, using oxygens pKa values here, okay? If we have a carboxylic acid we know that our pKa is going to be a 5, so with sulfur it should be something around 5, right? So, I'm going to do that about 5 and we know that our alcohol, well not our alcohol, our water's pKa HOH, we know that's 16, right? So, over here I'm going to say this is about 16, okay? So guys, what's happening here is that this is going to be pronated by this and then we end up with the conjugate base over here, and the conjugate acid, right? So, what's going to happen is that one of these lone pairs and the sulfur is going to come in, grab this hydrogen, deprotonate our sulfur and take electrons onto that sulfur and then we end up with this. And now guys it's our job to figure out which direction the equilibrium lies. So, we know that we need to go from the lower pKa to a higher pk, so this is a pKa of about 5 and this is a pKa of about 16. We're definitely going to be heading in this direction mostly, right? Our equilibrium is going to lie towards the right, towards the products and we're going to have that, the small arrow to the other side for our equilibrium, right? Let me clean that up a little bit. So guys, the equilibrium is definitely going to favor the products, this is our curved arrow mechanism and let's move on to the next one.