 In this video, we'll look at naming esters. Esters are somewhat similar to carboxylic acids and amides. They have a carboxyl group, the C-double bondo, plus the extra oxygen. But where in carboxylic acids that extra oxygen is bonded to a hydrogen, here for esters, the oxygen is bonded to a hydrocarbon group. Esters are synthesized, or made, by joining a carboxylic acid molecule with an alcohol molecule. And we'll look at this reaction in a later video. So, just to reiterate that point, to make esters, you react a carboxylic acid with an alcohol. So here's how this first ester would be made. You would react hexanoic acid with propan-1-ol, and they would join together, and you would get this molecule. The part on the left, the part that's directly attached to the carbonyl group, came from the carboxylic acid, and the other part used to be the alcohol. So, to name this, we call the part that used to be the carboxylic acid the main chain, and it takes the suffix 08. So, this part of the molecule is called hexanoate. And the other part, which used to be the alcohol, is named in the same way as an ordinary alcohol substituent. So with three carbons, it would be called propyl. And then you put these two parts together, and the full name is propylhexanoate. Now, note that there is a space between the two words. This is the only time with esters that you'll leave a space between the two parts of a name. No hyphen, no comma, just a space. Okay, how about this second one? First, identify the main chain. That's the bit on the carbonyl side here. And it has two carbons. Don't forget the carbon that's part of the carbonyl. So we'll call that part ethanoate. Then the substituent part has four carbons, so it's butyl. And together, that makes butylethanoate. Lastly, this one. Again, identify the main chain. It's here, but it has a branch on it. Well, no matter, we deal with it like any other molecule. The main chain is five carbons long, so pentanoate. And on carbon number three, there's a methyl group, so it becomes three methyl pentanoate. But then we need to indicate the esters substituent here. That has only one carbon, so it's going to be called a methyl as well. Because it's the special esters substituent and not stuck to the main chain, it gets put out the front of the name as a separate word. So that gives us methyl three methyl pentanoate.