So remember from organic chemistry that hydroxide molecules contain a full negative charge on the oxygen. And so that makes it a strong nuclear file. And so this nitrogen takes away the H atom. And these two electrons that were in the sigma bond now nucleophilically attack the carbon and this displays the pi bond in the same way that we displace the pi bond here. And in the same way that we form this tetrahedral intermediate, we also form a tetrahedral intermediate in step five. And once again, to stabilize that relatively unstable and negatively charged tetrahedral intermediate, we have this oxyanion hole that contains the partially positive charge H atoms that can stabilize this full negative charge.