And the last example that we're going to talk about is thionyl chloride, so it's s o c l 2. This is another good step forward, because now we actually have four different atoms in our molecule.
So I show that here, so in green, you have what's called a carboxcylic acid group, a c o o h, which gets converted by s o c l 2 to a c double bond o c l or an acid chloride.