Now Zaitsev's rule. The loss of water follows Zaitsev's rule when we undergo an elimination or dehydration reaction of an alcohol. Now it's used when the neighboring carbons have different numbers of hydrogens. Under Zaitsev's rule, we're going to say the OH atom is lost from the alcohol carbon and the H atom is lost from the neighboring carbon with fewer hydrogens.
If we take a look here at this reaction, we have an alcohol that is not symmetrical. Here we have our neighboring carbons. One neighboring carbon has two hydrogens and the other neighboring carbon has three. Following Zaitsev's rule, we would lose an H from the carbon in red since it has fewer hydrogens to lose.
When we do this, we still lose the OH from the alcohol carbon, so it's gone. We'd lose an H from the chapter two group. So now it's just chapter and they need to maintain their four bonds so they'd form a double bond between each other. So again, we utilize Zaitsev's rule when our neighboring carbons next to the alcohol carbon have different numbers of hydrogens. This is just a way of us making sure that we're making the correct alkene at the end.