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Video transcript

let's practice identifying functional groups in different compounds so this molecule on the left is found in perfumes and let's look for some of the functional groups that we've talked about in the previous videos well here is a carbon-carbon double bond and we know that a carbon-carbon double bond is an alkene so here is an alkene functional group here's another alkene right here's another carbon-carbon double bond what is this functional group we have an OHA have the rest of the molecule so we have our Oh H ROH is an alcohol so there's also an alcohol present in this compound next let's look at aspirin so what functional groups can we find in aspirin well here is an aromatic ring right so this is an arene so there's an arene a functional group present in aspirin what about this one up here we have an OHA and the oxygen is directly bonded to a carbonyl so let's go ahead and write that out we have an OHA where the oxygen is directly bonded to a carbon double bonded to an oxygen and then we have the rest of the molecule so hopefully you recognize this as being a carboxylic acid so let me go ahead and write that out here so this is a carboxylic acid all right our next functional group we have an oxygen and then oxygen is directly bonded to a carbonyl alright so here's a carbon double bonded to an oxygen so let's write this out we have an oxygen directly bonded to a carbonyl and then for this oxygen we'd have the rest of the molecule so that's all of this stuff over here and then on the other side of the carbonyl we have another R group so I'll go ahead and write that in so that is an ester Roc double bond o R is an ester so there's an ester functional group present in the aspirin molecule let's look at some of the common mistakes that students make one of them is students will say a carboxylic acid is an alcohol so let me write out here a carboxylic acid so we can talk about that so sometimes the students will look at that and say oh well I see an OHA and then I see the rest of the molecule so isn't that an alcohol but since this oxygen is right next to this carbonyl this is a carboxylic acid so this is an example of a carboxylic acid if we moved the O H further away from the carbonyl let's go ahead and draw one out like that so here is our carbonyl and now the O H is moved further away now we do have an alcohol now we have a know H and then the rest of the molecule so this would be we going to use a different color here so now we are talking about an alcohol so this is an alcohol and what would this one be we have a carbonyl and then we have an R group on one side and R group on the other side that is a ketone let me draw this out so when you have a carbonyl and an R group on one side and R group on the other side it could be the same R group that could be a different R group sometimes you'll see like our prime drawn for that so this is a ketone so now we have a ketone and an alcohol so two functional groups present in the same compound so hopefully you can see the difference between between this compound and this compound this one is a carboxylic acid and this one is a ketone and an alcohol alright another common mistake that I've seen a lot is on this functional group right here on aspirin students will look at this oxygen here and say okay I have an oxygen and then I have an R group on one side and I have an R group on the other side so in our group on one side of the oxygen and R group on the other side of the oxygen isn't that an ether well this is RoR would represent an ether however we have this carbonyl here so this carbonyl right next to this oxygen is what makes this an ester how can we turn that into an ether let me go ahead and redraw this molecule here so I'll first put in our our ring so I drew the double bonds a little bit differently from how I drew it up here but doesn't really matter and then I'll put in I'll put in our carboxylic acid up here and now when I draw in this oxygen I'm going to take out the carbonyl alright so now the carbonyl is gone and now do have an ether so this this actually is an ether now we have an oxygen we have an R group on one side and we have the rest of the molecule over here on the other side so now this isn't ether so hopefully you see the difference there look for the carbonyl right next to the auction that makes it an ester alright so more common mistakes that students make is they mix up these two functional groups so let's look at the functional groups in these two molecules here we start with benzaldehyde and the name is a dead giveaway as to the functional group we're talking about an aldehyde here so first we have our aromatic ring or Eyring and then we have an aldehyde we have a carbonyl and we have a hydrogen that's directly bonded to the carbonyl carbon so we have an r group and then we have a carbonyl and then we have a hydrogen directly bonded to our carbonyl carbon that is an aldehyde if we took off that hydrogen and we put a ch3 instead that would be the compound on the right so now we have a ch3 directly bonded to this carbonyl carbon so now we have an r group on one side a carbonyl and then another r group so we have our C double bond o R and that is a ketone and you can tell by the ending of our name here that we have a ketone present in this compound so again this difference is subtle but it's important and a lot of students mess this up and aldehyde has a hydrogen directly bonded to this carbonyl carbon but if there's no hydrogen alright we're talking about a ketone here so our C double bond o R is a ketone finally let's look at one giant compound with lots of different functional groups and let's see if we can identify all the functional groups present in this molecule this molecule is is called atenolol this is a beta blocker so this is a a heart medication all right let's look for some functional groups we've seen before here is that aromatic ring so we know that an arene is present in atenolol so let me go ahead and write this in here next we have an oxygen and there's an R group on one side of the oxygen up one side of the oxygen and R group on the other side of the oxygen so R oor we know that's an ether so there's an ether present in this compound next we have an OHA and then the rest of the molecule so our OAH would be an alcohol so there's an alcohol present alright next we have a nitrogen with a lone pair of electrons there's an R group on one side there's an r group on the other side so this is an amine alright so we have an amine and finally over here on the left so this is one that is is messed up a lot we do have a nitrogen with a lone pair of electrons on it so it's tempting to say we have an amine here but this nitrogen is right next to a carbonyl so it's not an amine it's an amide or amid alright so this this is an amide so a lot of people pronounce this amid alright so it's not an amine so let's talk more about the difference between an amides and an amine so let me go ahead and draw out another compound here so we can see we have our NH two alright and then we have our carbonyl so for this one we have our nitrogen our nitrogen directly bonded to the carbonyl carbon and that's what makes this an amide we can move these electrons into here and push these electrons off onto the oxygen so resonance is possible with this compound so this is an amide or an amid if we move the nitrogen further away from the carbonyl let's go ahead and do that over here so we have our carbonyl and now our nitrogen is further away now we don't have any more resonance right you can't you can't draw a resonance structure showing the delocalization of the lone pair of electrons on the nitrogen so now now we do have an amine so this over here this would be an amine let me change colors I'm gonna do blue this is an amine and then what would this one grupe we have a carbonyl and then we have an R group on one side R group on the other side that is a ketone so this is a ketone and an amine and then over here we have an amide or an image so make sure make sure to know the difference between these I've seen a lot of very smart students mess up the difference between these two functional groups