 In this video I'll do a few more worked examples of naming more complex molecules. I'm just going to stick this slide in here to remind you of the prefix versions of the names of each functional group. Okay, so this first one looks a bit weird, but study it carefully and you can see that there is an ester group in the middle and an aldehyde on the end. Of these two the ester has the higher priority so it's going to dictate the name. You may need to consult your notes to remember ester naming protocols. First of all, work out which bit of the molecule originally came from the carboxylic acid. That's the part that's closest to the carbonyl group so that's this part and that becomes the main chain. It has four carbons so being an ester that ends in 08 and that gives us butan 08. Now we have the aldehyde group and the other part of the ester still to deal with. Let's do the aldehyde first. It's on the main chain so we're going to number from the carbonyl group backwards treating the aldehyde as a substituent. When it's a substituent an aldehyde is called oxo same as a ketone. So the main chain part of this molecule is going to be called 4-oxo butan 08. Okay, now the other part of the ester, the bit that used to be the alcohol, it has three carbons and we name it like a normal hydrocarbon substituent so it's called propyl. And the full name is propyl 4-oxo butan 08. Okay, second example. What are the functional groups? Well, it has two carboxylic acids, one on each end so it's going to be called a dioic acid. There are six carbons in the main chain so that becomes hexane dioic acid. Note that like alcohols and amines when there are two or more of them the alkane part of the name retains its E. And this molecule also has a bunch of halogens. So the carboxylic acid groups have equal priority so we could number from either end but two of the three halogens are closer to the right hand end so we should go from there to give the lowest numbers. That gives us 3-4 dichloro and 3-bromo. Putting this all together with the bromo and chloro in alphabetical order gives us 3-bromo, 3-4 dichloro-hexane-dioic acid. Note that I wouldn't necessarily mark you down for calling this hexane 1-6-dioic acid but the numbers are unnecessary. Carboxylic acid groups have to be on the end of the chain and if there are two of them then they must be on the two ends of the chain so the numbering is redundant.