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Organic chemistry
Course: Organic chemistry > Unit 3
Lesson 5: Functional groupsMore functional groups
An overview of the carbonyl-containing functional groups.
Want to join the conversation?
- Shouldn't the IUPAC name be pentan-2-one rather than 2-pentanone?(8 votes)
- Yes ,According To IUPAC pentan-2-one is the more preffered name(6 votes)
- Is there any functional group formed with a triple bond?(2 votes)
- Yes. Alkyne group is associated with triple bond.(3 votes)
- Are 2-pentatone and pent-2-one the same?(3 votes)
- If you meant pentan-2-one then yes, they mean the same molecule.(3 votes)
- hey Sal, why, in this video, you have taken butane instead of butene while there is a double bond present. According to me, the name of the compound should be butenal; and following it, the second one should be pentenone and similarly, the third one-butenoic acid . Please check if I am right or not?(1 vote)
- I'm not entirely sure what you're asking, but the compound is called butane instead of butene because the double bond in part of the functional group, and is not part of the longest carbon chain. It would be butene if the oxygen was removed as well as one of the single bonds. I hope this helps!(7 votes)
- Can we replace CH3 with R? I know its stupid but I need to confirm so that I can be sure.(1 vote)
- Sort of. R is just what we use to denote some other set of atoms in organic chemistry. It could be CH3, CH2CH3, or maybe just H, or something else. It won't always be CH3.(5 votes)
- can a acyl/acid halide have a different halogen, or can it only have Cl?(2 votes)
- It can have the following halogens: F, Cl, Br, and I (I don't think Astatine forms acyl halides, and Tennessine definitely doesn't)
For example,Acetyl Iodide or Ethanoyl Iodide(CH₃COI)
(2 votes)
- Can we consider propanal and propanone to be structural isomers since both have a formula of C3H6O ?(2 votes)
- could you give some of the properties of the functional groups?(2 votes)
- Is an aldehyde an ketone?(1 vote)
- No, they're definitely different. Ketones have 2 carbons bonded to the carbonyl carbon (the one with the double bond), aldehydes have a carbon and a hydrogen bonded to the carbonyl carbon.(3 votes)
- According to priority of principal functional group alkenes has higher priority than alkynes.
But in a compound
CH thriple bond C-CH=CH-CH=C-H-H ,the IUPAC name is Hexa-1,3-dien-5-yene and it shows the suffix yene which means alkyne has priority. Therefore actually alkenes or alkynes has priority?(2 votes)- 1) Double bonds only have priority over triple bonds if there is a tie (e.g. a double bond and one end and a triple at the other end of a linear molecule), otherwise whatever numbering gives the lowest locant (position number) wins.
2) The priority for numbering is not the same as the priority for what becomes the suffix. For the suffix in a molecule with both double and triple bonds the name will end with #-en-#-yne.
Discussions of this that refer to the IUPAC "blue book" of rules:
https://chemistry.stackexchange.com/questions/63152/what-is-the-order-of-nomenclature-priority-among-an-alkyl-side-group-a-double-b?noredirect=1&lq=1
https://chemistry.stackexchange.com/questions/28202/why-is-it-en-yne-and-not-yn-ene-what-is-the-explanation-for-this-iupac-specifi
https://chemistry.stackexchange.com/questions/26735/why-doesnt-the-double-bond-get-preference-for-suffix-in-iupac-naming-of-an-hydr?noredirect=1&lq=1(1 vote)
Video transcript
- [Voiceover] All the
functional groups in this video contain a carbon-oxygen
double bond, and we call a carbon-oxygen double bond a carbonyl. So here you can see a carbon-oxygen double bond in this functional group, and here's another one
in this functional group, and here's another one down here. For the first functional group this is called an aldehyde, so an aldehyde has an R group on one side of the carbonyl and a hydrogen on the
other side of the carbonyl. As an example lets look at this compound. So here is our carbonyl, our
carbon-oxygen double bond, and then on this side we
have a hydrogen directly bonded to this carbonyl carbon. On the left side we have this R group, so the carbonyl carbon gets a number one, it gets the lowest number possible, and then this carbon
would get a number two, this carbon would get a number three, and this carbon would get a number four. So we have a four-carbon aldehyde. So how do we name a four-carbon aldehyde? Well a four-carbon
alkane we know is butane, so one, two, three, and four, and we know that this compound is called butane. An aldehyde has an A-L
ending, so if you see an A-L ending, that indicates
the presence of an aldehyde. So we're gonna lose the E
from butane, and add on A-L, so the name of this
molecule becomes butanal. Let me write that out
here, so this is butanal. Next lets look at a
ketone, so a ketone has an R group on one side of the carbonyl, and an R group on the
other side of the carbonyl. So for our ketone example
lets look at this compound. We're gonna number to give our carbonyl the lowest number possible, so we're gonna start numbering from the left side of our compound, so this would get carbon number one. The carbonyl carbon would
be carbon number two. This is carbon number three, this is carbon number four, and
this is carbon number five. So we have a five-carbon ketone. A five carbon alkane, let me go ahead and draw out a five-carbon alkane here, this would be called pentane,
so that would be pentane. A ketone has an O-N-E ending, so ONE indicates the presence of a ketone. So we're gonna lose the E
from pentane, and add ONE. So this would be pentanone,
so this is pentanone. We also need to indicate the
position of the carbonyls. The carbonyl is at carbon two, so we need to write 2-pentanone, and that's because we could draw another molecule that's pentanone, but this could have the
carbonyl at carbon three, so let me go ahead and write
that in here, one, two, three. So this compound would be 3-pentanone, and 3-pentanone and 2-pentanone
are different molecules, so that's why we need to indicate
the position of the carbonyl. For the aldehyde up here,
we didn't need to indicate that the aldehyde is at carbon one. That's the only place
that it could possibly be. Notice that an aldehyde has this hydrogen directly bonded to the carbonyl-carbon, where as a ketone has, if we look at the carbonyl group right
here, we have a carbon on one side, see H 3 on
one side in this case, and we have a carbon on this side directly bonded to that carbonyl carbon. So that's the difference between an aldehyde and the ketone, and a lot of students have a hard time
telling the difference between an aldehyde and a ketone. Look for this hydrogen directly bonded to the carbonyl-carbon
and that's an aldehyde. Next we have a carboxylic acid, so a carboxylic acid has an R group on one side of the carbonyl,
and an O-H on the other side. Some students think
that this is an alcohol at first, but this is not an alcohol. This O-H is right next to this carbonyl, and that changes the properties. Carboxylic acids have different
properties from alcohols. For an example of a carboxylic acid, over here on the right we
know that our carbonyl-carbon gets number one, so
that's carbon number one. This is carbon number two, carbon number three, and carbon number four. So a four-carbon carboxylic acid. So a four-carbon alkane up here was butane, so we're gonna have OIC acid as our ending, so
it would be butanoic acid for the name for this compound. and that's just one of the
names, so one of the names for this molecule would be butanoic acid. Alright, probably the most
famous carboxylic acid is a two-carbon carboxylic acid, so I can draw it like this really quickly, and this is called acetic acid. Vinegar is just a dilute-solution
of acetic acid in water. Alright, our next functional group is called an acyl halide, or you can also call it an acid halide, and you're pretty much talking about acid-chlorides in organic chemistry, and so here is our carbon-oxygen double bond, and then on this side we have an R group, and the right side we have a chlorine. So acyl halides come from carboxylic acid, so this is an example of a
carboxylic acid derivative, and an example of an acyl halide on the right here, we have our carbonyl, and then we have our
halogen, and the reason I like to call them an acyl halide is this right here on the left,
this is an acyl group, and on the right we have our halogen, so this would be acetyl
chloride, is one of the names for this, but you can also
call them an acid halide. There are carboxylic acid derivatives, so some professors prefer one term, and some professors prefer the other term. Our next functional group
is an acid anhydride. So here is our carbonyl,
here's the R group, and instead of a chlorine
like we had up here we have all of this
over here on the right, and so this is an an acid
anhydride, or just an anhydride. This is also a carboxylic acid derivative. You can form an acid anhydride from a carboxylic acid,
and for the example over here on the right we
have acytic anhydrides. Next functional group is called an ester. So an ester is another
carboxylic acid derivative. So a carboxylic acid had a
hydrogen in this position, but now we have an R group, so we have our carbonyl, we have an O-R, and
then we have an R on the left, so that's an ester, and
here's an example of an ester over here, so
we have an ethyl group instead of a hydrogen, so for acytic acid, let me go ahead and
draw acytic acid again. Acytic acid had a hydrogen right here, and now we have an ethyl group, so instantly we know we're
talking about an ester, we're not talking about a carboxylic acid. If you wanted to name this ester, you have this ehtyl group,
so that would be ethyl, and then this part would be acetate, so ethyl acetate would be the name. Now for the names of all of these, you're gonna get to them
later in the course, so it's probably not that
important to name these compounds, but it's good to start
hearing these things now. And finally, our last functional
group is called an amide, atleast that what I call it, but there are several different ways to
pronounce this functional group. The dictionary says, atleast
my dictionary says, amides, or amids, are the two preferred
ways to pronounce this. You'll probably hear
amids as one of the most common ways to pronounce this. A lot of professors say amid,
and some professors get pretty upset if you don't pronounce
this the way that they want. I've heard many more ways
to pronounce this functional group too, like amides,
and all kinds of things. Use whatever pronunciation
your professor wants. That's always the way to do things. Now we have a carbonyl, notice
we have a nitrogen right next to the carbonyl-carbon,
so nitrogen directly bonded to the carbonyl-carbon, lone pair of electrons on the nitrogen, so that's an amide functional group, or an amid functional group, so these Rs could be hydrogens, you could
be talking about hydrogens or you could be talking
about alkyl groups, so there's lots of different
examples of amides, or amids. On the right is an example,
so our carbonyl-carbon gets a number one, so this would be one, this would be number two,
this would be number three, this would be a number four, so a four-carbon amide would be butanamides. Let me go ahead and write that down here, so this would be butanamide,
or butanamid, depending on how you prefer to pronounce
this functional group.